Surface Coatings on Terracotta Objects from Boeotia and ...

Surface Coatings on Terracotta Objects from Boeotia and Taranto 400 - 200 BC

Korstanje, UvA, 2019

Surface Coatings on Terracotta Objects from Boeotia and Taranto 400 - 200 BC - the influence of composition on the

susceptibility for detachment

Fiep Korstanje BA 11741686 [email protected]

MA Thesis Conservation and Restoration of Cultural Heritage Specialisation: Glass, Ceramics and Stone

University of Amsterdam, Amsterdam Supervisor: Kate van Lookeren Campagne – Nuttall 21-06-2019



Table of Contents

Introduction 1

1. The Case-Study Objects 3

1.1 Context of the Objects: From Excavation to Museum 3

1.2 Object Description 5

1.3 Object Condition and Surface Coating 8

1.3.1 Standing Woman with Chiton and Himation (APM00257) 9

1.3.2 Head of Woman (APM00277) 9

1.3.3 Standing Woman with Hand on Side (APM00394) 10

1.3.4 Lower Part of Walking Woman (APM01145) 10

1.3.5 Eros (APM01161) 11

1.3.6 Incense Burner (APM14207) 11

2. State of the Art: Greek Terracotta Figurines 13

2.1 Production of Ancient Terracotta Objects 15

2.1.1 Forming the Object 19

2.1.2 Coating Materials 21

2.1.3 Coating Application 24

2.2 Factors Influencing the Loss of Surface Coatings 25

2.2.1 Production 25

2.2.2 Morphology and Chemical Composition of Ceramic and Coatings 26

2.2.3 Coating Composition 28

2.2.4 Burial Conditions 29

2.2.5 Treatment on/after Excavation 29

3. Experimental 33

3.1 Methodology 33

3.1.1 Hirox Optical Microscopy 34



3.1.2 pXRF Analysis 34

3.1.3 X-ray Diffraction 34

3.1.4 SEM-EDX 35

3.2 Results and Interpretation 36

3.2.1 Hirox Optical Microscopy Results and Interpretation 36

3.2.2 pXRF Results and Interpretation- Major Elements Measured 38

3.2.3 XRD Results and Interpretation 41

3.2.4 SEM-EDX Results and Interpretation 42

4. Conclusions from the Analysis 54

Conclusion 58

English Summary 62

Dutch Summary 64

List of Figures 66

Bibliography 71

Acknowledgements 74

Appendix I: Images 76

Appendix II: Images Objects from Museum Database and Literature 84

Appendix III: Indicating Coating Layer, Hirox Images, XRD Measurement Points of 88 SEM-EDX Samples

Appendix IV: XRD Results of Case Study Group 102

Appendix V: SEM-EDX Results of Case Study Group 110


1 Korstanje, UvA, 2019

Introduction

From the Bronze Age, terracotta objects were produced on a large scale in Ancient Greece.

These objects were decorated with different organic and mineral pigments that were

applied on top of a light-coloured surface coating.1 The composition of these surface

coatings often remains unclear, being referred to for instance as slip layers or as surface

coatings containing, or mixed with, calcium carbonate.2 Because it is unknown what type

of coating is present, it has been decided in this research to refer to this layer as a ‘coating’.

The application of a surface coating on terracotta was done from the fifth century BC

onwards.3 At the Allard Pierson Museum, an important collection of these Greek

archaeological terracotta sculptures is stored. On some objects, a much larger percentage

of the surface coating remains than on others. The exact factors that have led to this

difference in loss of surface coating are unknown. Probable causes for the loss of surface

coating are the composition of the coating, burial conditions as well as how the objects

were treated on or after excavation.

This thesis discusses the research undertaken into the possible reasons for the variation in

percentages of loss of the coatings and the way in which loss occurs on these terracotta

objects. The main research question is: ‘In how far does the composition of the surface

coating on ancient Greek terracotta figures influence the susceptibility of the coating

layer?’, with focus on a specific region and period.

For this research, six terracotta objects with varying conditions of surface decoration were

selected from the collection of the Allard Pierson Museum. Three originate from Boeotia

(in Greece) and three are from Taranto (now Italy). All objects date between the fourth and

the second century BC.4

It is hoped that the results of this research will aid the preservation of Greek terracotta

figures, by giving greater insight in susceptibility of the coating layer for damage.

1 Robert A. Lunsingh Scheurleer, Grieken in Het Klein: 100 Antieke Terracottas (Amsterdam: Allard Pierson Museum, 1986), 9. & Paula G. Leyenaar-Plaisier, Griekse Terracotta's: Uit De Collectie Van Het Haags Gemeentemuseum (Den Haag: Haags Gemeentemuseum, 1986), 12-21. & Herman Brijder, "Griekse Godinnen En Meisjes in Het Klein," in Kleur! Bij Grieken En Etrusken, ed. Vincenz Brinkmann and Herman Brijder (Amsterdam: Allard Pierson Museum, 2006), 57. & R. A. Higgins, "The Polychrome Decoration Of Greek Terracottas," Studies in Conservation 15, no. 4 (1970): 273. 2 Anne Rinuy and Francois Schweizer, "Analysis of the White "ground" and Ancient Adhesives Found on Canosa Vases (south Italy) of the Third Century B.C.," in Proceedings of the 18th International Symposium on Archaeometry and Archaeological Prospection, Bonn, 14-17 March 1978; Archaeo-Physika, Band 10, Rheinisches Landesmuseum Bonn (Köln: Rheinland-Verlag GmbH, 1978), 255. & Riemer R. Knoop, Antefixa Satricana: Sixth-century Architectural Terracottas from the Sanctuary of Mater Matuta at Satricum (Le Ferriere) (Assen/Maastricht: Van Gorcum, 1987), 21. 3 Gloria S. Merker, "Corinthian Terracotta Figurines: The Development of an Industry," Corinth 20 (2003): 234. 4 Allard Pierson Museum Archeologische Collectie, December 2004, accessed February 1, 2019, http://dpc.uba.uva.nl/archeologischecollectie.



Chapter 1. The Case-Study Objects

For this research an assemblage of six terracotta objects from the Allard Pierson Museum

in Amsterdam, The Netherlands, was analysed (appendix I fig. I.1-I.21). The group was

selected based on several criteria. The main criterion for selection was a variation in the

condition of the white coating layers to enable comparison of objects. In addition, the

provenance and date of the object needed to be known and literature about the specific

objects available. In order to enable comparisons between the objects, the object’s dates

needed to be as close as possible. Two different places of origin were chosen to see

whether a correlation between a production region and coating composition could be

made. Based on these characteristics, a pre-selection of fifteen objects was made and

handheld XRF analysis (see chapter 3) was carried out to get an overview of the type of

coating present on the objects in order to make sure that the objects would provide a

balanced range. The selection of six suitable objects was made based on the percentage of

aluminium, silica or calcium in the coating which suggested the presence of either clay

minerals or chalk.

In this chapter the archaeological context of the objects will be discussed. In addition, an

overview of the six objects is included and the condition of the objects is described,

including a detailed description of the surface coating (table 1 & 2).

1.1 Context of the Objects: From Excavation to Museum

Three of the objects were produced in Taranto. This city, which is currently in Italy, was a

Greek colony during the fourth and third century BC. The other three objects originate from

different cities in Boeotia, a region in central Greece (fig. 1). The place of production has

been based on the stylistic characters of these objects.

Five out of six objects used in this research were part of the collection of C.W. Lunsingh

Scheurleer, who was professor of classical archaeology at the University of Leiden. Lunsingh

Scheurleer was a collector of ancient artefacts who bought objects from dealers and

collectors often at international art fairs. Most items were acquired by Lunsingh Scheurleer

between 1900 and 1932. Between 1912 and 1920 many objects from Boeotia and Taranto

were acquired, which make up a large part of the collection nowadays. The objects were

acquired by the Allard Pierson Museum in Amsterdam when the collection was up for sale

and at risk of being separated.5

One object, the altar/incense burner (APM14207), was donated to the Allard Pierson

Museum in 1998. No further information is known about who donated this object.

5 Leyenaar-Plaisier, Griekse Terracotta's, 3. & Lunsingh Scheurleer, Algemeene Gids, ed. L.J. Elferink (Amsterdam: Allard Pierson Museum, 1937), VIII. & Lunsingh Scheurleer, Grieken in Het Klein, 7.



Furthermore, the date of production and place of production is known as defined by the

museum conservator or curator.6

In the beginning of the twentieth century, little emphasis was put on preserving

information regarding the context and history of such objects in collections. Often hardly

any information exists about where objects were found or excavated and who the objects

were sold to. For this research, only objects of which the provenance and a production date

are determined by the conservator or curator, are included.

Some of the objects have been photographed for publications for museum databases.

Pictures taken of the objects previous to this research have been used to try to detect

possible changes over time in the condition of the surface coating that is present on the

objects (appendix II fig. II.1-II.9). If there was a clear difference between the amount of

surface coating in the old pictures and the objects now, this may be an indication that the

coatings were very friable and this would assume that a problem with the attachment of

the coatings was present, although this is considered unlikely as they have been sitting in

storage since their acquisition. Even though the quality of some of the pictures is not very

good and some pictures are in black and white, it appears that between now and when the

pictures were taken hardly any signs of loss of surface coating can be detected.

6 Allard Pierson Museum Archeologische Collectie, http://dpc.uba.uva.nl/archeologischecollectie.

Figure 1. Map depicting Taranto (modern Italy) and Boeotia (Greece).

Source: Adapted from Google Maps. “Taranto and Boeotia” Accessed June 5, 2019.

Boeotia

Taranto



1.2 Object Description

7 A chiton is “a long woollen tunic worn in ancient Greece.” Oxford English Dictionary, “Chiton,” accessed June 5, 2019, https://en.oxforddictionaries.com/definition/chiton. 8 A himation is “an outer garment worn by the ancient Greeks over the left shoulder and under the right.” Oxford English Dictionary, “Himation,” accessed June 5, 2019, https://en.oxforddictionaries.com/definition/himation.

Inventory Number

Date Place of Origin Dimensions (mm)

Colour of Ceramic Body

Description

APM00257 (fig. 2)

400-200 BC Livadhia, Boeotia (Greece)

175h x 60w Yellow-red Standing woman wearing a chiton7 and over that a himation8 until the knees that covers the head and arms. The object has a rectangular fire hole at the back.

APM00277 (fig. 3)

400-200 BC Thebe, Boeotia (Greece)

90h x 58w Red-brown Head of a woman with long hair over the shoulders, a tiara and hair ribbon.

APM00394 (fig. 4)

400-200 BC Tanagra, Boeotia (Greece)

215h x 85w Red Standing woman wearing a chiton and over that a sideways draped himation, also over the head. The right hand is placed on the waist. The object has a rectangular fire hole at the back.

APM01145 (fig. 5)

400-300 BC Taranto (modern Southern Italy)

190h x 125w Yellow-red The lower part of a woman who is walking to the left. The figure is wearing a flowing himation with plunges that was held tight at the waist and depicted a girl bringing sacrificial gifts.

APM01161 (fig. 6)


210h x 85w Light red Figure of naked Eros with spread wings and short hair. The body is robust and the wings are large relative to the body. The quills of the feathers are marked with ridges.

APM14207 (fig. 7)


80h x 68w Light beige with a grey core

The object is a rectangular altar or incense burner with four decorated sides: A. Leto leaning on a rod, cornucopia, Apollo with lyre; B. Poseidon with trident, Amymone; C. Dionysus hugging Ariadne, satyr; D. Woman garlanding a tropaion on stone. The top of the object is closed with the exception of a small slot. A profile is visible on top which is partly decorated with an egg-and-dart motif. On two corners of the top cover, palmette and volute shaped ornaments are present, which are connected by an edge with ramage motifs.

Table 1. Object Description



Figure 2. Standing woman with chiton and himation (APM00257)

175h x 60w

Figure 3. Head of woman (APM00277)

90h x 58w

Figure 4. Standing woman with hand on

side (APM00394) 215h x 85w

Figure 5. Lower part of walking woman

(APM01145) 190h x 125w

More images of the objects, including the back and with a scale, can be found in appendix I.



Figure 6. Eros (APM01161)

210h x 85w

Figure 7. Incense burner (APM14207) Side A

80h x 68w



Table 2. Object Condition and Surface Coating

1.3 Object Condition and Surface Coating

Inventory Number

Location Surface Coating Description Surface Coating Surface Decoration Deterioration Surface Coating Remaining Coating

APM00257 Coating present on outside of object. No coating visible on inside, possibly due to encrustation layer. Encrustation layer visible on top of the coating.

Coating: thin and evenly applied. Only visible in places where encrustation layer is missing. Colour: bright white.

On the legs, blue and pink pigments are present.

Layer seems worn on protruding areas such as nose.

70%

APM00277 White coating on the front and on part of the back.

Coating: thin and evenly applied. Along the lower areas, like around the nose, a thicker layer is present. Colour: bright white.

Red-brown paint/surface coating is present on the hair and traces of black paint are present on the eyes. A light pink paint seems to have been applied on the face.

Layer is worn on the more protruding areas.

70%

APM00394 Coating present on outside of object. No coating visible on inside, possibly due to encrustation layer. Encrustation layer visible on top of the coating.

Coating: thin and evenly applied. Colour: bright white.

Black pigment is present near the eyes and hair. On the lips red pigment is present, and red and light blue pigments are present on the clothing. On the face some traces of light pink pigment are visible.

Layer seems worn. 90%

APM01145 Coating present on outside of object, not on inside.


Yellow-brown pigment is present on the himation.

Only small parts of coating remain in the form of slivers on top of the object as well as a thin and evenly applied surface in between the ridges.

10%

APM01161 White coating on the object, excluding the hair region, the inside and the back as well as part of the front of the wings.


Red, brown and pink traces of paint are present on the body. On the wings, also traces of green/blue and yellow can be detected.

Layer seems worn. No fresh breaks along missing coating visible.

60%

APM14207 Coating present on outside of object, not on inside.


Pink traces are visible on all sides as well as on top of the object.

Breaks along missing coating indicate that coating has detached and is not worn.

40%



1.3.1 Standing Woman with Chiton and Himation (APM00257)

The ceramic of the object is yellow-red in colour. A coating layer is visible all over the front

and the back of the object. On top of the coating layer, a grey encrustation layer is present,

which is characterised by a white or off-white deposit on top of the coating layer. Also, on

the inside an encrustation layer is present. The coating can be detected due to its very

white colour, which can be seen on the face, mainly along the lower areas such as on the

side of the nose, chiton as well as on the legs of the object. The coating is very smooth and

seems to have been applied evenly (fig. III.2, III.4). Whether a coating was also applied on

the inside is not visible due to the encrustation layer. On the legs blue and pink pigments

are present (fig. III.3).

The coating is missing along the ridges, on high areas, as well as on the face (fig. III.2).

Furthermore, on the back of the object an area is present where surface coating is missing

(fig. III.5). In the ridges of the ceramic in this area, some coating is still present, showing

that coating was applied here. About thirty per cent of the substrate area is exposed. No

fresh breaks are present around the areas where surface coating is missing. Instead the

layer seems to gradually become thinner up to areas where coating is missing, which would

suggest that the layer is removed mechanically. Loss of the encrustation layer can however

be detected on the back of the object, at the same place where the coating is missing. This

may suggest that when the encrustation layer was removed, the coating was removed as

well. Furthermore, no encrustation layer is present along the ridges and high areas.

1.3.2 Head of Woman (APM00277)

The ceramic has a red-brown colour. A white coating is present on the facial area of the

object, mainly in the lower areas. Coating is missing in the more protruding areas (fig. III.7).

A brown/red coating layer, which is similar in structure to the white coating is present on

the hair and partly on the back of the object (fig. III.11). On the rest of the back of the object

no coating is present. It seems that this area has never been coated since the dirt that is

present on the coating has the same colour and amount of soiling as is present on the areas

where no coating can be detected. This dirt looks like a very thin grey wash and is only

present on the back of the object. The white coating is in some areas present underneath

the red coating, around the hair. No white coating can be detected underneath the rest of

the hair colour. The coating is very smooth and seems to have been applied thinly (fig. III.8,

III.9). Traces of black are present on the eyes. A light pink paint seems to have been applied

on the face.

Only the head of the object remains. The body is missing. The coating is missing along the

more protruding areas such as the nose, chin, cheek and the hairband. No fresh breaks are

present around the areas where surface coating is missing. Instead the layer seems to



gradually become thinner around areas where coating is missing, which would suggest that

the layer is worn or was removed mechanically (fig. III.7, III.10). About seventy percent of

the surface coating remains.

1.3.3 Standing Woman with Hand on Side (APM00394)

The object has a very bright red ceramic colour and an encrustation layer is present all over

the object. In areas where the layer is missing, a bright white coating is visible (fig. III.13-

15). The coating seems to have been applied all over the object since in most areas where

the encrustation layer is missing, which is evenly over the object, coating is present

underneath. Assuming that the coating is present under the encrustation layer, about

ninety per cent of the surface coating remains. Even though it is not visible everywhere due

to the encrustation layer, the coating seems to have been applied thinly. Black pigment is

present near the eyes and hair. On the lips, red pigment is present, and red and light blue

pigments are present in the ridges of the clothing along the legs. On the face, some traces

of light pink pigment are visible.

The object has been broken into four pieces on the side. The pieces have been adhered

during a previous restoration and one area in the back has been filled (fig. III.12, III.16). The

surface coating seems to have been kept intact due to the encrustation layer on top.

1.3.4 Lower Part of Walking Woman (APM01145)

The ceramic has a yellow-red colour. Traces of a very white coating are present all over the

object, as well as traces of an encrustation layer. The traces are mainly present between

the ridges of the object (fig. III.18, III.20). The white coating appears to have been applied

thinly and evenly over the object (fig. III.18). Yellow-brown pigment is present on the

himation.

The top part and the feet of the object are missing. There are brushstrokes present on the

leg of the object, assuming that the object was severely cleaned by a brush (fig. III.21, III.22).

About ten per cent of the surface coating is still present on the object. Some fresh breaks

are present around the areas where surface coating is missing, in combination with the

layer gradually becoming thinner around areas where coating is missing (fig. III.19, III.21).

This would suggest that the layer was removed mechanically, but could also have detached.



1.3.5 Eros (APM01161)

The ceramic has a light red colour and a bright white coating is present on the object, excluding

the hair region, the inside and the back as well as part of the front of the wings. The coating seems

to have been applied thinly and evenly. The top of the wing does not seem to have had a

white coating applied, since no traces of coating are present here at all, in contrast to areas

where coating is missing but traces are still present (fig. III.24). Possibly a different type of

decoration was present on these parts of the wing. Pink traces of paint are present all over

the body. Traces of brown are visible in the hair region. On the wings, also traces of

green/blue and yellow can be detected, mostly in between the ridges of the wing (fig.

III.29).

The object is missing part of one of the wings as well as one of the legs and the back of the

other foot. The foot has been adhered together. About sixty per cent of the surface coating

remains. Furthermore, no fresh breaks are present around the areas where surface coating

is missing. Instead the layer seems to gradually become thinner around areas where

coating is missing, which would suggest that the layer is worn or was removed mechanically

(fig. III.25-27).

1.3.6 Incense Burner (APM14207)

The ceramic is light beige and has a grey core.9 A bright white surface coating has most

likely been present all over the outside of the object. The coating seems to have been

applied evenly and is thin (fig.III.36-37). Some traces of the coating are still present along

the upper decoration. Pink traces are visible on all sides as well as on top of the object (fig.

III.32-33). Also, a grey encrustation layer is present on the object (fig. III.32-33).

Some traces of a previous restoration are present in the form of adhesion of the object and

a fill. One upper corner of the object is missing. About forty per cent of the surface coating

remains. Along the depictions the coating seems to be missing from the object (fig. III.31,

III.35). On the background of the reliefs, the coating is still attached. On the more

protruding areas of the depictions, however, the coating is often missing. Also, on the top

of the object as well as on the decorations on the upper region, most coating is missing.

Where the surface coating is missing, a break edge is visible (fig. III.36-37). On handling

during conduction of the XRD analysis, a very small part (about 2mm) of the coating with

terracotta detached which must already have been loose (fig. III.31). This flake came off

attached to a small layer of terracotta. The pigments on top of the object seem to have

broken in smaller pieces, but are still attached to the object (fig. III.40-41).

9 A grey core appears when the firing cycle is too short so that the organic material is not fully burnt out of the ceramic core.



Chapter 2. State of the Art: Greek Terracotta Figurines

This section discusses what is written in literature about the production process of

terracotta objects and the application of a coating (table 3). Four main sources have been

found that describe forming and firing of the object. Three of these sources, namely

Lunsingh Scheurleer (1986), Leyenaar-Plaisier (1986), and Kaufmann (1915) give a general

overview of the production of ancient Greek terracotta figurines and discuss the stylistic

differences of several archaeological finds. The authors give a general description of the

steps that were undertaken to produce these objects, including collecting the clay, forming

the objects, and how the objects were decorated and fired. These sources were written

using few references to other sources. The reason for this is probably that no or few earlier

published sources for the production of these objects were available. It has proved

impossible to track-down where the information given by these authors comes from. Also,

the information is mostly art-historical. This is due to the unavailability of instrumental

analysis in that period but also because the authors were not material scientists. Brijder

(2006), who focusses on the coloured decorations on ancient Greek terracotta objects only

gives short, descriptive statements on how objects were produced and what type of coating

was applied.

In addition, Richter (1948), Oliver (1986), Knoop (1978) and Lulof (1991) described ancient

Greek terracotta objects in which research was done into the provenance of the object or

its style. In the article by Richter (1948), a terracotta head from the Metropolitan Museum

is described, Oliver (1968) discusses ceramic objects from two Apulian tombs and Knoop

(1987) and Lulof (1991) discuss architectural and monumental terracotta from Satricum,

Italy. Each of these sources have included short statements on the coating that is present

on the terracotta objects discussed. The scope of their research focussed on the description

of the objects and the use, meaning and style of these objects. These statements, even

though very useful to get an overview of what could have been applied on terracotta

objects, does not give enough background information to compare the type of coating that

is present and their deterioration. The reason that little chemical analysis has been

implemented in earlier research is probably due to the limited analytical facilities as well as

the research focus on the composition and deterioration processes within archaeology.

More recent literature, as well as a few earlier sources, include chemical analysis of the

composition of the clay or the surface coating. The first available sources that have

discussed instrumental analysis of surface coatings on terracotta objects, are Higgins in

1970 and Rinuy and Schweizer (1978). Higgins describes the use of XRD analysis conducted

on different ancient Greek terracotta objects. How this analysis was conducted or the exact

results have not been included. The same counts for Rinuy and Schweizer, who have

researched 3rd century BC Canosa vases, which are in provenance and production date very

close to the figurines discussed in this research. Even though no methodology or results

were included, this source has provided the first chemical analysis of objects comparable



to the objects in this research. Unfortunately, no deterioration patterns were discussed in

this source, making it impossible to make comparisons between the objects.

Three more recent sources have included an instrumental analysis. First of all, Bordignon

et al. (2008) researched potsherds and polychrome terracotta from Cerveteri, Italy. In their

research, micro-Raman spectroscopy, X-ray Diffraction (XRD) and Fourier-Transform

Infrared Spectroscopy (FTIR) were used to analyse the surface coatings. Furthermore,

Costello and Klausmeyer (2013) analysed the surface coatings on 3rd century BC terracotta

statues from Canosa. FTIR, SEM, and TGA were applied in this research. Finally, Kakoulli

(2017) researched objects with a similar provenance and production date. This research

applied XRF analysis to determine the composition of the surface coatings. The chemical

analyses discussed in these sources include information that can help to interpret the

results of instrumental analysis in this research. The results of these analyses have been

included in table 3 and in paragraph 2.1.2, which describes the different coating materials

that have been discussed in the literature.

To conclude, even though many sources are available in which the presence of a surface

coating on terracotta has been mentioned, few of these sources included instrumental

analysis. The articles that have included chemical analysis, though useful to get an idea of

the composition of surface coatings on ancient terracotta, have mostly either not included

the exact methodology (Higgins (1970) and Rinuy and Schweizer (1978)) or have discussed

objects that have a different provenance or production date, such as Bordignon. Two

articles, however have included extensive analysis and results on the composition of

surface coatings on terracotta objects, namely Costello and Klausmeyer (2013) and Kakoulli

et al. (2017), who both discussed the composition of 3rd century BC Canosa (Italy) terracotta

vases. These two sources are therefore most relevant to this research.



2.1 Production of Ancient Terracotta Objects

Suitable potters’ clay is found all over Greece and Italy and was used to create objects such

as figurines.10 The objects made of the iron-rich earthenware clay that was found are

referred to as “terracottas”, based on the Italian word “terra” which means clay or earth.11

Terracotta figurines were made from the Bronze Age onwards. The objects, as well as the

knowledge of how to produce them, spread from the Greek mainland along the

Mediterranean Sea. Different types of objects can be traced back to specific production

centres and can be dated based on stylistic elements.12

During the Classical Period (480-323 BC) and the beginning of the Hellenistic/Roman Period

(323BC-300AD), to which the objects used in this research date, some of the largest

production centres of terracotta objects were in Boeotia (Greece) as well as Athens

(Greece) and Taranto (modern Italy).13

In the Classical Period, such figurines mainly had a religious function, and would either be

used as votive statues or during funerary practices. However, terracotta objects were also

used as toys. During the fourth century BC, terracotta statues also started to be used as

decorations in for instances living areas. An example of this are incense burners which were

solely made as decorations. During the Hellenistic/Roman Period, the function of

terracottas as art objects increased dramatically. Terracotta objects were mainly found in

graves, houses, sanctuaries and temples.14

From the fifth century BC onwards all terracotta figurines were decorated with pigments

that were added on top of a white surface coating.15 This coating would be applied for

several reasons. First of all, a surface coating would provide a light-coloured base for other

colours that would not be visible on a red-fired ceramic and coatings could create surface

structure or can even out the surface of an object.16 Moreover, the application of a slip

coating decreases the porosity of an object.17 Table 3 provides an overview of the sources

found.

10 Lunsingh Scheurleer, Grieken in Het Klein, 9. 11 Lunsingh Scheurleer, Grieken in Het Klein, 9. 12 Leyenaar-Plaisier, Griekse Terracotta's, 12-21. 13 Leyenaar-Plaisier, Griekse Terracotta's, 14. & Lunsingh Scheurleer, Grieken in Het Klein, 17-18. 14 Lunsingh Scheurleer, Grieken in Het Klein, 14. & Leyenaar-Plaisier, Griekse Terracotta's, 15. 15 Lunsingh Scheurleer, Grieken in Het Klein, 9. & Leyenaar-Plaisier, Griekse Terracotta's, 12-21. & Herman Brijder, "Griekse Godinnen En Meisjes in Het Klein," 57. & Higgins, "The Polychrome Decoration Of Greek Terracottas," 273. 16 Sabine Fourrier, "East Greek and Cypriote Ceramics of the Archaic Period," Cyprus and the East Aegean, October 2008, 134. & Erophile Kolia, "Archaic Terracotta Reliefs from Ancient Helike," Hesperia: The Journal of the American School of Classical Studies at Athens 83, no. 3 (September 2014): 431. & Brijder, "Griekse Godinnen En Meisjes in Het Klein,” 57. & Owen S. Rye, Pottery Technology: Principles and Reconstruction (Washington, D.C.: Taraxacum, 2002), 41. 17 Harry Fraser, Ceramic Faults and Their Remedies (London: A. & C. Black, 2005), 118. & Prudence M. Rice, Pottery Analysis, Second Edition: A Sourcebook (University of Chicago Press, 2015), 5.



Author & Date Object(s) studied

Region of study

Date of object(s)

Aim/area of study Analysis used to study surface decoration

Description/ composition of surface coating

Production details

Kaufmann 1915

Terracotta objects

Greek-Roman from different find sources

Greek-Roman (509-27BC) and Coptic period (300-700)

History of koroplastic production and function of objects

None given ‘Kalkmilch’ (chalk milk)

Coating applied after firing. Background decorated with black, red or yellow or completely painted (p.20)

Richter 1948

A terracotta head from the Metropolitan Museum.

Greek End of the Archaic Period (800-480BC)

Study of one object None given ‘yellowish white slip’ (p332) ‘fine whitish slip’ on all Greek and Etruscan terracotta objects (p.335)

Coating applied by brush before firing. Painted colours also applied before firing (p. 335)

Oliver 1968

Ceramic objects from two Apulian tomb groups

Canosa, Italy 3rd and 4th century BC

Reconstruction of two Apulian tomb groups from Canosa. Focus on pottery and the meaning of the objects within their context.

None given White lime wash, white ground or whitewash

Coating was applied after firing

Higgins 1970

Terracotta objects

Greece Not specified Analytical research of the polychrome decoration

XRD White clay containing gypsum (calcium sulphate dihydrate) (p.275)

None given

Rinuy & Schweizer 1978

Several terracotta vases

Canosa, Italy 3rd century BC Production techniques of these vases and terracotta figurines

AES, XRD, TGA Slip made of pure kaolinite

Coating applied after firing



Lunsingh Scheurleer 1986

100 terracotta objects from the collection of the Allard Pierson Museum

Greece Not specified Catalogue including stylistic research of terracotta objects

None given White clay-slip Coating applied solely to the front of the object before firing

Leyenaar-Plaisier 1986

Terracotta objects

Greece Not specified Exhibition catalogue of objects from the Allard Pierson Museum

None given White paint on clay basis, called an engobe or ‘deklaag’

Coating applied before firing. Maximum firing temperature possible in the kiln was 1100˚C

Knoop 1987

Architectural terracotta

Satricum, Italy 6th century Description, context and historical meaning of architectural terracotta

None given Slip containing calcite. The term slip is used since this ‘refers to simply any surface coating’ (p.196)

Coating was applied by brush before firing. Firing temperature of maximum 890 degrees Celsius, since this is the critical decomposition temperature of the calcite (p. 196)

Lulof 1991

Monumental terracotta statues

Satricum, Italy Late Archaic period (800-480BC)

Description, context and historical meaning of monumental terracotta

None given Slip: ‘a fluid suspension of clay in water, sometimes mixed with calcite to produce a white colour’ (p.57)

Coating was applied on a damp surface

Merker 2003

Terracotta figurines

Corinth, Greece

Ancient times (1200BC- 600AD)

The development of Corinthian terracotta figurines

None given White slip is present from the 5th century BC onwards (p.324)

None given

Brijder 2006

Terracotta objects

Mediterranean area

Not specified Colour used on terracotta objects, including the production of terracotta objects in general

None given Kaolin (aluminium silicate) (p.57)

Coating applied before firing



Bordignon 2008

White-on-red potsherds & high-value polychrome terracotta

Cerveteri area, Italy

Orientalising period (800-600BC) & Archaic period (800-480BC)

Spectroscopic identification of kaolin used in pigments on terracotta and kaolin found in the Monte Sughereto quarry

Micro-Raman spectroscopy, XRD, FTIR

High-purity kaolin which contains quartz, dickite is dominant, anatase as minority mineral (p.27)

None given

Fourrier 2008

Ceramic vessels

East Greece and Cyprus

Archaic Period (800-480BC)

The relation between Cyprus and East Greece based on ceramic vessel circulation

None given Slip layer in red and white

None given

Costello & Klausmeyer 2013

Two terracotta statues

Canosa, Italy 3rd century BC Identification of materials and methods used during manufacturing and restoration

SEM-EDX and TGA White slip made of kaolin (p.380)

Coating applied after firing

Kolia 2014

Several terracotta reliefs

Helike, Greece Archaic Period (800-480BC)

Stylistical research and research into the manufacturing process

None given Mostly slip and sometimes a clay wash

None given

Kakoulli 2017

Two polychrome terracotta vases

Canosa, Italy 3rd century BC Production techniques of vases and terracotta figurines

XRF Kaolinite (p.109) Coating applied after firing (p.109)

Table 3. Overview of Literature Discussing the Production Process of Terracotta Objects and the Application of a Coating



2.1.1 Forming the Object

Collecting Clay

The clay that was used for the production of terracotta objects would have been locally

collected. Most clay that is available and can be extracted is secondary clay which is formed

from degraded stone and transported by rivers or wind. Most iron-rich earthenware clays

are suitable for making low-fired terracotta figurines. This clay is earthenware clay and

contains impurities such as iron oxide, and often coarse inclusions such as small stones or

sand.18 According to Lunsingh Scheurleer and Leyenaar-Plaisier the clay would be washed

to remove coarse material that was present in the clay, a process that is called levigation.19

The clay would then be kneaded to remove air bubbles and make the clay homogenous.

Larger particles would have been separated from the clay by mixing it with water and

waiting for the heavy particles to settle.20 Both Lunsingh Scheurleer and Leyenaar-Plaisier

mention that after washing, sand, mica or crushed pottery was added to the clay to limit

its shrinkage and to prevent cracking during firing.21

Moulding the Clay

Terracotta objects were made by a terracotta potter, also called a koroplast.22 During the

Bronze Age, mainly solid terracotta objects were created, formed by hand. From the eighth

century BC onwards, the technique developed and objects started to be made in moulds.

These objects, which were hollow, require less clay than solid objects and are easier to

fire.23 To produce these moulds, first a clay object would be made, or an already existing

object would be used. Over this matrix, a layer of clay, the patrix, would be folded. After

drying, the patrix could be used as a mould for the production of multiple objects. These

moulds would be filled with one piece of clay, or first a thin layer of clay would be added

after which the rest of the clay was pressed into the mould. The extra layer of clay was

18 Daniel Rhodes, Clay and Glazes for the Potter (Mansfield Centre, CT: Martino Publishing, 2015), 11. & Lunsingh Scheurleer, Grieken in Het Klein, 9. & Grimshaw and Searle, The Chemistry and Physics of Clays (London: Ernest Benn Limited, 1960), 333. 19 Joseph V. Noble, "The Technique of Attic Vase-Painting," American Journal of Archaeology 64, no. 4 (1960): 313. 20 Noble, "The Technique of Attic Vase-Painting," 313. 21 Leyenaar-Plaisier, Griekse Terracotta's, 4. 22 Carl Maria Kaufmann, Graeco-agyptische Koroplastik: Terrakotten Der Griechisch-romischen Und Koptischen Epoche Aus Der Faijum-Oase Und Andren Fundstatten (Leipzig, 1915), 19-20. & Eleni Hasaki, "Ceramic Kilns in Ancient Greece: Technology and Organization of Ceramic Workshops," PhD diss., University of Cincinnati, Diss, 2006, abstract in 73. 23 Lunsingh Scheurleer, Grieken in Het Klein, 9. & Brijder, "Griekse Godinnen En Meisjes in Het Klein," 57.



sometimes used to create a smooth layer over the object.24 Often only the front of the

object was made using a mould. The back would be formed by hand.25

From the Hellenistic period onwards, plaster moulds were also in use. During the Hellenistic

period also more complex figures were created, often made out of several pieces. These

pieces were adhered together with clay slip before firing.26

Finishing the Object

After the object was moulded, an air hole was cut in the back to prevent the ceramic from

cracking during firing due to moisture that was trapped in the object. Furthermore, this air

hole allowed heat to reach the inside of the object. Afterwards, final touches would be

made by the koroplast and the object was dried. At this stage an object would shrink up to

ten per cent.27

Firing

Figurines were fired before or after the application of a coating (table 3). Firing was done

in three stages in a kiln. While Kaufman states that firing was in kilns in which temperatures

could go up to a maximum of 1150 degrees Celsius,28 Rice claims that terracotta was mostly

fired to a temperature between 800 and 900 degrees Celsius.29 Objects could be placed a

kiln by using kiln supports.30 First, the objects would be fired in an oxidising state in a

temperature between 750 and 950 degrees Celsius. At this stage, air was allowed in the

kiln. Secondly, the air flow would be locked in a reducing stage. Finally, the air would be let

back in, giving the ceramic core a red colour.31 After firing, a coating layer would be applied,

if this had not already been applied before firing, and organic or mineral pigments would

be added as decoration.32

24 Leyenaar-Plaisier, Griekse Terracotta's, 4. & Lunsingh Scheurleer, Grieken in Het Klein, 11. 25 Leyenaar-Plaisier, Griekse Terracotta's, 12. & Brijder, "Griekse Godinnen En Meisjes in Het Klein, 57. 26 Leyenaar-Plaisier, Griekse Terracotta's, 5-6. 27 Lunsingh Scheurleer, Grieken in Het Klein, 9 & 11. & Brijder, "Griekse Godinnen En Meisjes in Het Klein," 57. 28 Kaufmann, Graeco-agyptische Koroplastik, 19-20. & Hasaki, "Ceramic Kilns in Ancient Greece.” 29 Rice, Pottery Analysis, 5. 30 Hasaki, "Ceramic Kilns in Ancient Greece." 31 Lunsingh Scheurleer, Grieken in Het Klein, 12. 32 Leyenaar-Plaisier, Griekse Terracotta's, 6. & Lunsingh Scheurleer, Grieken in Het Klein, 12.



2.1.2 Coating Materials

Different types of coating on ancient Greek terracotta objects are discussed in literature,

which can be divided into clay-based and chalk-based coatings (table 3).

Slip Coating

The first, and most often discussed process, is the application of a slip coating. Slip, also

known as engobe or barbotine, is a suspension of clay in water. Coatings of slip consist of

clay minerals to which colorants or pigments can be added.33 According to Versluys (1993),

who discusses modern pottery techniques, slip can be made by either adding water to clay

or by using clay powder, which is obtained from clay that has completely dried and mixed

with water.34 This slip could be made of the same clay used for the ceramic body, to which

water and colorants are added. However, if lighter colours were needed as a background,

for instance when colours would be applied, white clay for instance containing kaolinite

(Al2Si2O5(H2O)4), could be used in which no colouring impurities are present. Kaolinite is a

white or grey clay mineral which is the chief constituent of kaolin.35 Kaolin is defined as “a

fine soft white clay, resulting from the natural decomposition of other clays or feldspar”.36

Kaolin mines are present both in Italy as well as in Greece. When writing about Greek

figurines, Brijder claimed that white colourants could be added to these coatings but has

not specified what exactly.37 The viscosity of this slip coating can be adjusted by adding or

extracting water from the mixture.38 After application, the object would be dried and fired.

Another possibility is that the coating would be applied after firing.

The presence of a slip coating is discussed by several authors. Richter, Lunsingh Scheurleer

Leyenaar-Plaisier and Brijder39 for instance, mention the presence of a slip coating that was

applied before firing. Brijder specifies the presence of aluminium silicate (kaolinite) in this

slip coating. These four authors, who have written about ancient Greek terracotta objects

in general, did not support their claims with chemical analysis and focus on the historical

and stylistic aspects of ancient Greek terracottas.

33 Rhodes, Clay and Glazes for the Potter, 250. & Luk Versluys, Het Kleiboek: Oude Technieken En Nieuwe Mogelijkheden (Leuven: Kritak, 1993), 231. & Grimshaw and Searle, The Chemistry and Physics of Clays, 56-57. 34 Versluys, Het Kleiboek, 232. 35 Oxford English Dictionary, “Kaolinite,” accessed June 6, 2019, https://en.oxforddictionaries.com/definition/kaolinite. 36 Oxford English Dictionary, “Kaolin,” accessed June 6, 2019, https://en.oxforddictionaries.com/definition/kaolin. 37 Brijder, "Griekse Godinnen En Meisjes in Het Klein," 57. & Rye, Pottery Technology, 41. 38 Rye, Pottery Technology, 20 & 41. & Versluys, Het Kleiboek, 231-232. 39 Leyenaar-Plaisier, Griekse Terracotta's, 6. & Lunsingh Scheurleer, Grieken in Het Klein, 13. & Brijder, "Griekse Godinnen En Meisjes in Het Klein," 57. & Gisela M. A. Richter, "A Greek Terracotta Head and the "Corinthian" School of Terracotta Sculpture," American Journal of Archaeology 52, no. 3 (1948).

https://en.wikipedia.org/wiki/Aluminium

https://en.wikipedia.org/wiki/Silicon

https://en.wikipedia.org/wiki/Oxygen



A slip layer applied after firing is also discussed. Rinuy and Schweizer,40 who researched

terracotta vases from 3rd century BC Canosa applying Atomic Emission Spectrography (AES),

X-ray Diffraction (XRD) and thermogravimetry (TGA), concluded that a slip made of

kaolinite had been applied to the vases after firing. The results of this research have

however not been published and merely the presence of a non-fired kaolin slip is

mentioned. Furthermore, Costello and Klausmeyer41 have researched two terracotta

statues from Canosa, dating to the 3rd century BC, using Scanning Electron Microscopy with

Energy Dispersive X-ray analysis (SEM-EDX) and TGA. The results from SEM-EDX analysis

showed the presence of aluminium silicate, indicating that the surface coating consisted of

kaolin. TGA analysis showed that the clay layer had not been fired. Finally, Kakoulli,42 who

discussed similar terracotta vases, also from Canosa and dating to the 3rd century BC,

applied X-ray fluorescence (XRF). This research also concluded that the coating was made

of kaolinite and was applied after firing.

In addition, Merker, Fourrier, Kolia, Bordignon and Higgins43 discuss the presence of a slip

layer, not mentioning the time of application. In the article by Merker, the focus was on

the development of Corinthian Archaic terracotta figurines, Fourrier has researched

ceramic vessels from East Greece and Cyprus in archaeological research and Kolia has

discussed terracotta reliefs from Helike (Greece), dating to the Archaic Period (800-480BC).

Bordignon, who researched white-on-red potsherds from Cerveteri from the Orientalising

Period (800-600BC) and Archaic Period (800-480BC), analysed the surface coating that is

present on the shards.44 The analytical techniques applied included micro-Raman

spectroscopy, XRD and Fourier Transform Infrared Spectroscopy (FTIR). XRD showed the

presence of dickite, which is a polytype of kaolin. Even though calcite was also detected in

the terracotta body, it was believed that this calcite was probably present due to impurities

in the clay or the preparation method of the paint. Higgins used XRD analysis on the

polychrome decoration and surface coatings of several Greek terracotta objects dating to

different periods. The white coating from one of these objects, a terracotta figurine from

Tanagra (Italy) dating to 380BC, was found to have a clay layer containing a small amount

of gypsum. The exact results of this analysis were not included in the publication.

40 Rinuy and Schweizer, "Analysis of the White "ground", 255. 41 Susan D. Costello and Philip Klausmeyer, "A Re-united Pair: The Conservation, Technical Study, and Ethical Decisions Involved in Exhibiting Two Terracotta Orante Statues from Canosa," Studies in Conservation 59, no. 6 (2013). 42 Ioanna Kakoulli et al., "Application of Forensic Photography for the Detection and Mapping of Egyptian Blue and Madder Lake in Hellenistic Polychrome Terracottas Based on Their Photophysical Properties," Dyes and Pigments 136 (2017): 107. 43 Merker, "Corinthian Terracotta Figurines," 234. & Fourrier, "East Greek and Cypriote Ceramics," 134. & Kolia, "Archaic Terracotta Reliefs from Ancient Helike," 431. & Francesca Bordignon et al., "The White Colour in Etruscan Polychromes on Terracotta: Spectroscopic Identification of Kaolin," Journal of Cultural Heritage 9, no. 1 (2008): 27. & Higgins, "The Polychrome Decoration Of Greek Terracottas," 273. 44 Francesca Bordignon et al., "The White Colour in Etruscan Polychromes on Terracotta: Spectroscopic Identification of Kaolin," Journal of Cultural Heritage 9, no. 1 (2008): 27.



Coating Containing Chalk or Calcite

Calcite, also known as chalk (CaCO3) has also been mentioned as a component of surface

coatings on ancient Greek terracotta figurines. Calcium carbonate can occur in various

crystal forms including calcite or aragonite or can be present as sedimentary rocks such as

chalk and limestone. It is manufactured to produce different materials, such as plaster.45

Kaufmann, discusses the history of koroplastic, in which the production of these objects is

been described, and mentions the presence of a layer of Kalkmilch (chalk milk) on the

objects, which was applied after firing.46 Oliver discusses the presence of a ‘white lime

wash’, ‘white ground’, or ‘whitewash’ that was applied after firing in his research into

ceramic objects from 3rd and 4th century BC Canosa, Italy.47 It is unknown whether both

Kaufmann and Oliver believed this or if they were just describing what they saw, as their

research did not include any chemical analysis.

The same counts for Knoop and Lulof, who state that the coating present on 6th century

architectural terracottas from Satricum (Italy) was white because it contained large

quantities of calcite.48 The coating they both discussed has been described as a ‘slip’ and

according to the authors contained clay which was mixed with calcite. It is stated that these

coatings were applied after firing. Neither authors used instrumental analysis in their

research.

In conclusion, most literature mentions the presence of slip coatings that have been applied

to terracotta objects. The majority of the authors that discuss the application of slip before

firing did not undertake chemical analysis. This is in contrast to the sources that mention

the application after firing who did apply instrumental analysis. However, since this group

only consists of three research projects, one cannot assume that clay coatings were always

applied after firing. Furthermore, the sources that mention the presence of chalk or calcite

have not conducted chemical analysis or have not included this research in their

publication. This makes it difficult to confirm whether they mean that chalk and/or calcite

are indeed found as a surface coating on Greek terracotta figurines.

45 Grimshaw and Searle, The Chemistry and Physics of Clays, 281. & W. David Kingery, Pamela B. Vandiver, and Martha Prickett, "The Beginnings of Pyrotechnology, Part II: Production and Use of Lime and Gypsum Plaster in the Pre-Pottery Neolithic near East," Journal of Field Archaeology 15, no. 2 (1988): 219 & 221. & R. J. Gettens, E. W. Fitzhugh, and R. L. Feller, "Identification Of The Materials Of Paintings: Calcium Carbonate Whites," Studies in Conservation 19 (1974): 157. 46 Kaufmann, Graeco-agyptische Koroplastik, 19-20. 47 Andrew Oliver, The Reconstruction of Two Apulian Tomb Groups, 9-23. 48 Patricia S. Lulof, "Monumental Terracotta Statues from Satricum: A Late Archaic Group of Gods and Giants," PhD diss., Proefschrift Amsterdam, Universiteit Van Amsterdam, 1991, abstract in 118. & Knoop, Antefixa Satricana, 21.



2.1.3 Coating Application

Some authors include information on the way the surface coating would have been applied.

Richter, Higgins and Knoop state that the slip coating could have been applied by using a

brush or by dipping the object in the slip.49 Richter mentions the application of two ‘white

coatings’ on top of each other.50

None of these sources, however, give clear reasons for why they believe that these

application methods were applied and many of these authors discuss terracotta that is

different either in date or in origin from the objects discussed in this research. Therefore,

it cannot be said categorically which methods were used on the objects used for the

application of surface coatings on Greek terracotta figurines from the 4th and 3rd century

BC.

Thermogravimetry (TGA) analysis was conducted by Rinuy and Schweizer and Costello and

Klausmeyer who researched 3rd century BC Canosa vases. This analysis concluded that

unfired kaolinite was applied onto the ceramic after firing. No other sources discussing the

application of a slip coating have included instrumental analysis in their research focussing

on the moment in production that it was applied.

All sources discussing a coating with chalk or calcite have mentioned the application after

firing. When heated between 750 and 850 degrees Celsius, calcium carbonate will

decompose, making it impossible for a layer of chalk or calcite to still be present on ceramic

after firing.51 This would be the same if chalk was mixed in clay in high proportions.

49 Richter, "A Greek Terracotta Head," 332. & Higgins, "The Polychrome Decoration Of Greek Terracottas," 273. & Knoop, Antefixa Satricana, 21. 50 Richter, "A Greek Terracotta Head," 335. & Knoop, Antefixa Satricana, 21. 51 Harry Fraser, Ceramic Faults and Their Remedies (London: A. & C. Black, 2005), 17-19. & Prudence M. Rice, Pottery Analysis: A Sourcebook (Chicago: University of Chicago Press, 2015), 97-98 & 103. & Owen S. Rye, Pottery Technology: Principles and Reconstruction (Washington, D.C.: Taraxacum, 2002), 32.



2.2 Factors Influencing the Loss of Surface Coatings

Several causes for the detachment or loss of surface coatings from Greek terracotta

sculptures have been discussed in the literature. A combination of the chemical

composition of the coating and ceramic, the production process, and cleaning seem to

affect the loss of surface coatings.

2.2.1 Production

Application

The moment in the production process at which a surface coating is applied and the

viscosity of the coating have an influence on the susceptibility of any coating to

detachment. These factors can result in differential shrinkage. For example, a slip layer

which is a mixture of clay and water that is applied before firing, will have a higher water

content than the clay body. The slip will dry faster than the clay object itself, which contains

less water. This results in a faster shrinkage rate of the slip than that of the object.52 This

can cause stresses at the interface and lead to cracking and a weakened interface.53 If the

ceramic object is completely dry when a slip is applied, as is the case with coatings applied

after firing, the object will extract water from the applied slip, so that the slip cracks due to

loss of water.54

However, when slip is applied to partly-dried clay that is ‘leather-hard’, the first stage of

water evaporation will have finished so minimal differential shrinkage occurs, and the

object absorbs enough, but not too much, water.55

If the clay is too wet, a slip coating will have difficulty to attach to the object because of the

lack of water absorption and might run off the surface.56 Other factors that can influence

differential shrinkage in slip decoration is if the slip is not stirred properly before

application. This will lead to larger particles that may have settled, causing differences in

the shrinkage of the slip in certain areas.57 If thick layers of slip are applied, the slip may

crack due to the uneven drying, forming a network of more or less hexagonal lines.58 It has

been observed that flaking during firing occurs most often on convex areas as well as on

edges of an object.59 The reason for this could be that the coating layer has been applied

52 Fraser, Ceramic Faults and Their Remedies, 8-9. 53 Rhodes, Clay and Glazes for the Potter, 288. 54 Versluys, Het Kleiboek, 233. 55 Rhodes, Clay and Glazes for the Potter, 288. & Versluys, Het Kleiboek, 240. 56 Rye, Pottery Technology, 24. 57 Fraser, Ceramic Faults and Their Remedies, 29. 58 Rye, Pottery Technology, 41 & 43. & Fraser, Ceramic Faults and Their Remedies, 8-9 & 29. 59 Fraser, Ceramic Faults and Their Remedies, 30.



too thinly or that the evaporation rate of the clay is too fast in these areas due to the thin

clay layer.

Slip coatings, which consist of clay mixed with water, could be applied before or after firing.

The difference between fired ceramic and unfired clay is that ceramic becomes non-plastic,

hard and brittle due to firing, forming a vitrified layer.60 Not only would a fired slip layer

therefore be expected to be harder and less vulnerable, for instance to abrasion than an

unfired slip layer, the way these layers are bonded differs. Namely, an unfired slip will have

slightly been absorbed into the ceramic body, but has after that simply dried and is

susceptible to dissolution in water. The clay in a fired layer, on the other hand, will have

gone through chemical changes in the kiln, irreversibly fixing the structure in the clay

particles and resulting in a physiochemical bond with the terracotta. A surface coating

containing chalk would be applied after firing and would therefore be very susceptible to

abrasion and water.

2.2.2 Morphology and Chemical Composition of Ceramic and Coatings

Differential Shrinkage

During the production of terracotta objects, several stages occur during which shrinkage of

the clay object and a fired-on clay slip coating occurs. While shrinkage will occur during

firing, it is greatest during the drying process. Shrinkage of the clay object occurs when the

water that is present in the clay to make the clay plastic (malleable) evaporates. This

happens in two stages during drying. First of all, water inside the pores of the clay will

migrate to the surface of the object due to capillary action. Secondly, the water that is

present at the surface will evaporate out of the object.61 The evaporation of water from

the clay causes an object to shrink. Shrinkage will occur mainly in the first stage of the

drying process, until the object is considered ‘leather-hard’. During the second stage,

shrinkage will only occur at a minimal range.62

When a surface coating is applied onto a ceramic object, differential shrinkage can occur

between the coating and the ceramic. This happens when the shrinkage rate of the surface

coating and the ceramic object differ from each other. The shrinkage rate of clay or a slip

coating is based on the size of the clay particles and inclusions. Another reason is

differential packing of clay particles in an object. Areas where the particles are packed in a

60 Rice, Pottery Analysis, 473. 61 Fraser, Ceramic Faults and Their Remedies, 65. 62 Fraser, Ceramic Faults and Their Remedies, 8-9. & Rice, Pottery Analysis, 65.



flocculated way,63 it will dry faster than in areas where the particles are deflocculated64.65

The clay particles in slip coatings are mostly oriented in a deflocculated way, meaning that

they have the same charge and occur in dispersed suspensions instead of all having the

same orientation.66 Different clay types have different shrinkage rates. For instance, little

shrinkage occurs in clay that is rich in kaolinite.67

Due to differences in shrinkage rates, stresses can occur between a slip coating and the

object, which will cause cracks in the coating as well as stresses at the interface of the slip

and ceramic.68 In general, the most suitable slip would have a composition similar to that

of the clay body. The grain size of a slip should, however, be finer to prevent differential

shrinkage.

During firing problems with differential coefficient of expansion can occur which leads to

the shrinkage and expansion of the ceramic and slip at different rates when the

composition of the coating and ceramic are different. At five hundred degrees Celsius,

mechanically-bound pore water will evaporate from the object, causing the clay to shrink

about one per cent. At 573 degrees Celsius quartz that is present in the clay will rearrange

in a different order so it increases in volume, causing the object to expand. This point of

‘quartz inversion’ has to happen slowly to avoid cracking.69

Porosity

The susceptibility of a surface coating to loss, whether containing chalk or not, will be

different depending on the porosity of the clay. Namely, the higher the porosity of a slip,

the more friable it is and therefore it is more susceptible to mechanical ware and

abrasion.70 The porosity of ceramic is related to the clay composition and morphology as

well as the temperature at which an object has been fired. The higher the firing

temperature, the lower the porosity of a clay body and the more the clay will sinter.

Sintering occurs when clay is fired between 800 to 1000 degrees Celsius when the clay

particles fuse.71

63 “Flocculation is the agglomeration or coming together of particles in a suspension, such as a slip, forming "floes" and causing the suspension to thicken or settle.” Rice, Pottery Analysis, 476. 64 To deflocculate means “to disperse a fine clay suspension so that particles repel each other and the substance becomes more fluid.” Rice, Pottery Analysis, 475. 65 Rhodes, Clay and Glazes for the Potter, 251. 66 Rice, Pottery Analysis, 77. 67 Rice, Pottery Analysis, 67. 68 Rhodes, Clay and Glazes for the Potter, 13. 69 Prudence M. Rice, Pottery Analysis: A Sourcebook (Chicago: University of Chicago Press, 2015), 103. & Rhodes, Clay and Glazes for the Potter, 17-18. 70 Susan Buys and Victoria Oakley, The Conservation and Restoration of Ceramics (London: Routledge, 2011), 19 & 22. 71 Rice, Pottery Analysis, 93.



In a ceramic with a large number of open pores, liquids will be transported faster by

capillary action, meaning that when in contact with water, more will be drawn into the

object, which can lead to staining or saturation of the clay which leads to expansion.72

2.2.3 Coating Composition

The composition of a surface coating does not only influence the porosity of a surface

coating and the shrinkage rate, also the other characteristics related to stability of a surface

coating differ depending on its chemical composition.

When a layer of unfired slip comes in contact with water, the bonds between the clay

particles will break, leading to loss of coating.73 When chalk or calcite is added to a slip, the

calcium reduces clay shrinkage during drying.74 Moreover, when calcium carbonate is

applied to clay, the amount of water surrounding clay particles is reduced. This causes the

clay particles to move around less easily, forming cement-like compounds. The addition of

lime would therefore make a slip layer harder and more stable.75 This coating layer, even

though similarly attached to the surface as an unfired low-calcium slip layer, would be

expected to dissolve less quickly in water and be harder and therefore less vulnerable to

abrasion.

Furthermore, all clay and slip coatings contain fluxes, which are elements that reduce the

melting temperature of silica-rich materials. These fluxes can occur in different quantities.76

This means that when firing, the temperature and speed at which clay starts to sinter is

influenced by the type and amount of fluxes that are present in the clay. Calcium-rich clay,

for instance, shrinks more on firing than low-calcium clays because of its higher thermal

expansion coefficient.77 If the type and proportion of fluxes in the ceramic body and the

surface coating differ, tension at the interface can develop during firing.

72 Susan Buys and Victoria Oakley, The Conservation and Restoration of Ceramics (London: Routledge, 2011), 19. 73 Sebastian Teir et al., "Stability of Calcium Carbonate and Magnesium Carbonate in Rainwater and Nitric Acid Solutions," Energy Conversion and Management 47, no. 18-19 (2006): 3060-3061. 74 Grimshaw and Searle, The Chemistry and Physics of Clays, 282. 75 Marek Lichtarowicz, "Calcium Carbonate," The Essential Chemical Industry Online, accessed May 10, 2019, http://www.essentialchemicalindustry.org/chemicals/calcium-carbonate.html. 76 Rhodes, Clay and Glazes for the Potter, 251. 77 M.s. Tite, "The Production Technology of Italian Maiolica: A Reassessment," Journal of Archaeological Science 36, no. 10 (2009): 2077.



2.2.4 Burial Conditions

Ceramic expands when saturated with water. This can lead to differential expansion when

two layers of different clays are present. Stresses in the surface coating can occur, leading

to cracking of the object.78

Acids also affect ceramic and surface coatings. Since calcium carbonate as well as clays are

alkaline, the coating layers will be attacked chemically if they are in contact with acid.79 This

can happen when objects are buried in an acidic environment. When objects also have a

higher porosity, more acidic fluids will be drawn into the object, leading to more damage.

While burial environment could have influenced deterioration, one would expect the whole

surface to be fairly evenly affected and, as will be discussed, the localized nature of the

coating loss suggests that mechanical abrasion was the main factor.

2.2.5 Treatment on/after Excavation

When objects are excavated, finds such as terracotta figures are generally directly

processed and cleaned. The objects are given a number and the context information is put

in a data sheet. Soil is removed in order to gain as much information as possible about the

object. Cleaning mostly happens using water and brushes, both soft and hard. If objects

have an unfired coating and are therefore susceptible to water, these surface coatings can

be lost.80 If hard brushes are used abrasion of the surface coating and the ceramic can

occur, especially when a coating is low-fired and is therefore more fragile.81 When an object

has a surface relief, the protruding areas will suffer more from mechanical abrasion than

the lower areas.

It is quite possible that surface coatings are mistaken for an encrustation layer that has

been deposited on the surface during burial. These concretions are mainly calcite, gypsum

or a combination of these with silica.82 Such encrustation layers are insoluble and very hard

and generally have a white or off-white colour, which can be similar to surface coatings

Such deposits are impossible to remove using water or a brush.83

78 Grimshaw and Searle, The Chemistry and Physics of Clays, 421. 79 Gettens et al, "Identification Of The Materials Of Paintings," 166. & Grimshaw and Searle, The Chemistry and Physics of Clays, 651. & Teir et al., "Stability of Calcium Carbonate and Magnesium Carbonate," 3060. 80 Susan Buys and Victoria Oakley, The Conservation and Restoration of Ceramics (London: Routledge, 2011), 26. 81 Rye, Pottery Technology, 120. & Susan Buys and Victoria Oakley, The Conservation and Restoration of Ceramics (London: Routledge, 2011), 22. 82 Susan Buys and Victoria Oakley, The Conservation and Restoration of Ceramics (London: Routledge, 2011), 24-25. 83 Rye, Pottery Technology, 120.



Objects that have been cleaned with water are often dried in the sun at excavations,

causing rapid drying. Rapid drying can lead to damage to an object as well as stress in the

interface between the ceramic and a surface coating due to differential drying rates.

Abrasion of the ceramic and the surface coating can also occur due to incorrect handling of

such objects as well as during transport, if the objects are not packed properly.



Chapter 3. Experimental

In order to select a representative test set of six objects, pXRF analysis was conducted on a

preselected group of fourteen ancient Greek terracotta objects with a coating from the

collection of the Allard Pierson Museum. Further instrumental analysis was undertaken on

the selected six objects in order to determine what type of coating is present on each of

the objects in this research. First optical analysis was undertaken to record and compare

the nature and condition of each of the surface coatings. Then instrumental analysis was

undertaken using pXRF, XRD and SEM-EDX in order to learn more about the composition

and nature of the coatings. All instrumental analyses were conducted by Luc Megens (RCE).

3.1 Methodology

3.1.1 Hirox Optical Microscopy

Hirox optical microscopy was used to study the morphology and condition of the coating

to analyse whether differences between the structure of the ceramic, the surface coating

and in how far the coating is attached to the ceramic, could be detected. The focus was on

how the surface coating was attached to the ceramic and if any particularities could be

detected in the ceramic or the coating that could have influenced the detachment of these

coatings.

A Hirox KH-7700 3-D Digital Microscope with Photonic Optic lights was used. A raking-light

source was used from two directions to enable lighting between the ridges needed on some

of the objects. Different magnifications were used, ranging from twenty to one hundred

sixty.



3.1.2 pXRF Analysis

Handheld XRF (pXRF) 84 analysis was conducted on fourteen objects from the Allard Pierson

Museum, both on the coating layer as well as on the terracotta itself. Analysis was

conducted in the museum in order to minimise transport of the objects and to enable a

larger selection of objects to be analysed.

It was hypothesized that the coatings would contain aluminium silicate as well as colorants

and minerals, since at the museum the surface coatings were referred to as slip layers.

Higher percentages of Ca would suggest the presence of calcium carbonate.

3.1.3 X-ray Diffraction

XRD analysis was conducted using a Bruker D8 Discover micro-XRD, with Cu-Kalpha

radiation (40 kV, 30 mA) and GADDS with a 2D Vantec detector. The Bruker Eva 9 software

has been used to find matching patterns in the PDF2 database.

XRD analysis was undertaken in order to get information on the crystalline compounds that

are present in the surface coating and help identify what elemental compounds were

present in the coatings. XRD also has the ability to detect specific compounds that are

found in fired clay, such as gehlenite and wollostonite.

Each of the objects was placed in the XRD apparatus. Objects APM01145 and APM14207,

however, were too large, making it difficult to do the analysis. The points at which XRD

measurements were taken is indicated on the images in appendix III. For object APM14207

the sample that detached during handling was analysed.

In the condition report of the objects used in this research, it can be seen that an

encrustation layer is present on multiple objects. Especially on object APM00257 and

APM00394, where these layers cover most of the object, making it difficult to analyse a

spot that does not contain any encrustation and solely analyse the bright white surface

coating. Especially for these two objects, it must be kept in mind that the encrustations

could have influenced the results of the XRD analysis. A layer of calcium carbonate

encrustation would show the presence of calcite.

84 Thermo Scientific Niton XL3t energy-dispersive hand-held XRF analyzer, equipped with a silicon

drift detector. The Cu/Zn-mining mode was used, the duration of sampling was 112, 113 or 114s



3.1.4 SEM-EDX

SEM-EDX analysis was applied because SEM back-scattered images provide information on

the morphology of the coating. On these images the size as well as the amount of any

inclusions is visible. Coupled with EDX it was possible to do semi-quantitative analysis of

the elemental composition of the surface coating.

Furthermore, SEM-EDX can be used to map the distribution of different elements.85 This

makes it possible to detect where certain elements are in the sample. Based on this, the

type of coating that is present can be determined.

The measurements were conducted on two different apparatus due to technical problems.

Samples 1, 3 and 4 were analysed using a NovaNanoSEM450.86 Samples 7, 9 and 10 were

analysed with low vacuum (30pa) using a JEOL5910LV SEM.87

Sample Preparation

As the vacuum present in the SEM-EDX could possibly damage the objects during analysis,

it was decided to conduct the SEM-EDX analysis on samples taken from the objects.

Furthermore, samples were taken due to problems caused by the encrustation layer that

on some objects overlapped the surface coating. Analysing samples prevented the

encrustation layer of being analysed instead of the actual surface coatings.

Microsamples (+/- 0,2 mm) of the surface coating were taken from areas that were least

visible and as far as possible where damage had already occurred. In some cases, the

samples contained a microscopic amount of ceramic. The samples were as small as possible

to minimise any visible traces. The samples were removed under magnification using a

scalpel and were stored in glass containers.

The samples were embedded in Epofix epoxy resin. After curing, the samples were wet-

polished using silicon carbide paper with a grain size of 500, 600, 800, 1000, 2000 and 4000.

After which the samples were polished using micromesh with a grain size of 6000, 8000

and 12000.

85 Elizabeth Stuart-Buttle, Analytical Techniques in Materials Conservation (Chichester: Wiley, 2007), 91-94. & Prudence M. Rice, Pottery Analysis: A Sourcebook (Chicago: University of Chicago Press, 2015), 401-402. & Gilberto Artioli, Scientific Methods and Cultural Heritage: An Introduction to the Application of Materials Science to Archaeometry and Conservation Science (Oxford: Oxford University Press, 2013), 66-67. 86 A Silicon Drift Detector (SDD) Energy Dispersive X-ray Detector (EDX) was used with pathfinder software from thermo Scientific. CBS Concentric Backscatter detector (SEI because a very low accelerating voltage was used), GAD: Gaseous Analytic Detector (BSE), LVD Low Vacuum detector (SEI) was used as well. 87 Acceleration voltage of 20 kV, WD 10 was used. Energy-dispersive X-ray Spectroscopy was undertaken using a ThermoFisher Scientific SDD Ultradry detector and NSS (Noran System Seven) software.



3.2 Results and Interpretation

3.2.1 Hirox Optical Microscopy Results and Interpretation

Optical analysis using a Hirox 3D microscope (appendix III) showed that the structure of the

first five objects is quite similar, namely a bright white material with few inclusions (fig.

III.1-4). The layers seem to have been applied slightly more thickly between the ridges (fig.

III.2). A light grey encrustation layer, presumably calcium carbonate, is present on all

objects (fig. 8).

The way the coatings have detached is quite similar for objects APM00257 (fig. III.1-5),

APM00277 (fig. III.6-11), APM 00394 (fig. III.12-16) and APM01161 (fig. III24-30). The

coating layer is seen to become gradually thinner up to the area of loss, which would

suggest that the layer is worn or was removed mechanically, rather than detaching

simultaneously (fig. 9). This is also the case for APM01145 (fig. III17-23), where breaks also

occur along the missing coating (fig. III.19). This suggests that the bond between the coating

and ceramic is quite good. It can be seen that the objects on which pigments are still

present, have generally more surface coating remaining. This, in combination with

apparent traces of scratches from a brush or tool on object APM01145, would suggest that

some of the surface coating is missing due to mechanical abrasion (fig. 10).

On object APM01145 and APM14207 (fig. III31-41), coating exists where no decreasing

transition is visible (fig. III19, III36-37). The coating here seems to have detached leaving a

clean break in the coating, which suggest a poor bond between the coating and ceramic.

While handling this object, a very small fragment of the coating had detached, which

included a small layer of the terracotta.

Interpretation

It appears that the coating layer of objects APM00257, APM00277, APM00394 and

APM01161 is mainly missing due to abrasion by cleaning. The coating on APM01145 also

appears to be abraded due to cleaning, but fresh breaks are also present, suggesting the

coating has detached. On APM14207 the coating also seems to be detaching, again

suggesting that the coating on these two objects is more susceptible to detachment due to

poor bonding



Figure 8/III.32. Hirox Digital Microscope Image of

APM14207 encrustation and coating (20x)

Figure 10/III.22. Hirox Digital Microscope Image

of APM01145 brush marks (20x)

Figure 9/III.27. Hirox Digital Microscope Image

of APM01161 cheek (20x)



3.2.2 pXRF Results and Interpretation- Major Elements Measured

APM00236

Measurement Location

SiO2 CaO P2O5 K2O Al2O3 TiO2 Fe2O3 MnO

Clay 14 35 0,1 0,7 3,2 0,2 2,9 0,1

Surface Coating 11 45 0,1 0,5 2,5 0,7 2,1 0,0

APM00257



Clay 35 31 0,1 0,8 9,2 0,4 3,8 0,1

Surface Coating 23 32 0,1 0,1 11 0,2 2,4 0,2

APM00277



Clay 20 9,8 0,1 1,4 3,8 0,7 8,5 0,1

Surface Coating 25 20 0,0 0,4 2,0 0,2 3,3 0,1

APM00394



Surface Coating 14 41 0,1 0,2 1,5 0,2 1,3 0,0

Surface Coating 0,0 40 0,0 0,4 0,0 0,2 2,9 0,0

APM00978



Clay 41 11 0,6 2,1 4,3 0,5 4,0 0,1

Surface Coating 38 13 0,2 1,4 8,3 0,5 3,1 0,1

APM01040



Clay 30 21 0,0 0,7 13 0,6 4,5 0,1

Clay 23 38 0,0 0,9 5,9 0,3 2,8 0,1

APM01145



Clay 40 11 0,3 3,6 12 0,8 5,3 0,1

Clay 46 8,1 0,3 3,4 12 0,9 5,5 0,1

Surface Coating 40 6,8 0,3 2,9 16 0,9 4,9 0,1

Surface Coating 44 7,2 0,2 2,3 19 1,1 4,9 0,1



APM01161



Clay 29 21 0,5 2,0 5,3 0,4 3,7 0,1

Surface Coating 19 39 0,4 1,3 5,0 0,5 2,7 0,0

APM01256



Clay 28 13 0,1 1,4 4,7 0,5 4,1 0,1

APM01948



Clay 39 9,7 0,2 5,1 7,6 0,7 4,8 0,1

Clay 12 44 0,1 1,3 2,0 0,3 2,1 0,0

APM03264



Clay 7,9 47 0,0 0,2 1,1 0,1 2,2 0,0

Clay 17 24 0,0 1,9 3,6 0,8 6,8 0,1

Surface Coating 13 41 0,1 0,4 5,9 0,2 1,9 0,0

APM14071



Surface Coating 25 16 0,1 1,7 4,3 0,6 5,4 0,1

APM14076



Clay 27 11 0,1 2,8 5,5 0,7 3,6 0,1

Surface Coating 3,4 0,9 0,1 0,3 0,6 0,8 0,2 0,3

APM14207



Surface Coating 25 14 0,2 0,8 9,5 0,4 3,3 0,1



Interpretation

The result of the initial pXRF scan of the objects in the museum clearly show that the white

coating on the objects was not always a pure clay slip layer, as had been expected (table

4). Both clay slip layers and calcium-rich layers, probably chalk, appeared to be present.

Also, other materials were found including what appeared to be a layer of lead white which

seems to suggest a later treatment.

Six objects were chosen for further analysis as described in chapter one, with the aim to

compare objects with what appeared to be either a chalk-based or a clay-based slip coating.

The results suggested that the surface coating on objects APM00257, APM00277 and

APM00394 mostly contained chalk seen in the high percentage of calcium present in the

surface coating with relation to the aluminium and silica.

The surface coatings on object APM01145, APM01161 and APM14207 predominantly

consisted of silica and aluminium, with only minor amounts of calcium, which suggests they

were coated with a slip layer.

Inventory Number pXRF Interpretation

APM00257 Chalk

APM00277 Chalk

APM00394 Chalk

APM01145 Slip

APM01161 Slip

APM14207 Slip

Table 4. Interpretation pXRF



3.2.3 XRD Results and Interpretation

The XRD results can be found in appendix IV. The XRD results of the coatings on the six case

study objects were inconclusive. While the presence of calcite was detected on APM00257,

APM00394, APM01145 and APM01161, on APM00277 aluminium silicate and magnesium

silicate were present as well. Also, on APM01145 these compounds were detected. On

APM14207, aluminium silicate was detected.

Interpretation

The coating on APM00257 has clearly shown to contain calcite (table 5). This was also the

case for objects APM00349, APM01145 and APM01161. The layer on APM01145 appeared

to contain calcite and possibly talc or Mg₃Si₄O₁₀(OH)₂) or diopside (CaMgSi₂O₆), as can be

seen by the presence of magnesium and silica. On object APM00277 talc and diopside also

appeared to be are present together with clay minerals. Talc and diopside are chemically

related to chalk and commonly present in limestone and chalk deposits. APM14207

showed that the coating layer consisted of kaolinite.

On APM00257 and APM00277 it is not clear if the calcium carbonate from the surface

coating was recorded, or the encrustation or soil layer.

Inventory Number XRD Interpretation

APM00257 Calcite APM00277 Possibly talc and diopside (clay minerals) APM00394 Calcite APM01145 Calcite (probably thin layer), possibly also diopside APM01161 Calcite APM14207 Kaolinite

Table 5. Interpretation of XRD results



3.2.4 SEM-EDX Results and Interpretation

Observations during Sampling

During sampling observations could be made on the structure of the coating layer (table

6). These observations show that the coating on object APM00257, APM00277 and

APM00394 quickly crumbled when touched with the scalpel. The coating on objects

APM01161 and APM14207 were more compact and less friable. The sample from

APM14207 came off attached to the ceramic, indicating that the attachment between the

surface coating and the ceramic was good.

Inventory Number

Position of the Sample (appendix III)

Observations on the Coating Layer

APM00257 Back of the object

Coating quickly crumbled and some microscopic flakes detached

APM00277 Along a break edge of the object at the front, below the left neck line (from researchers’ perspective)

Coating quickly crumbled. The coating seems very friable

APM00394 Side of the object, where the coating layer was visible underneath the soil layer. It has been taken care that solely the coating was sampled

Coating quickly crumbled

APM01145 Back of the object Coating sample easily removed but quickly crumbled. Ceramic was attached to the sample

APM01161 Right rear end of the object Coating seems to be very stable

APM14207 The left bottom corner of side A A small sample had detached from the surface while handling

Table 6. Observations on the Coating Layer



Observations of Microscopic Samples

Each of the samples was photographed under a microscope88 and images of the samples

have been taken, which have been placed together with the results of the EDX analysis and

back-scattered images (fig. 11-25). Analysis of the images shows clear variations between

the surface coatings and the interfaces (table 7).

88 Microscope: Axio Imager.A2m. Objectives: EC Epiplan-NEOFLUAR 5x/0.13 HD, 10x/0.25 HD, 20x/0.5 HD and 50x/0.8 HD. Digital camera: ZEISS Axiocam 506 color and a Zeiss 60-C 1” 1,0x 456105 01 microscope camera adapter. Lighting: Colibri 7, brightfield (BF) and UV365.

Inventory Number

Observations of Microscope Samples

APM00257 The surface coating seems to be well integrated with the ceramic.

APM00277 Two layers of coating appear to be present, the top layer being denser and thinner than the bottom layer. The top layer is probably an encrustation layer. On the same sample in a different area, the coating seems whiter. The coating seems to lie on top of the clay and seems to be less integrated in comparison to APM00257.

APM00394 The interface between surface coating and the clay looks similar to that of APM00257 and seems to be well integrated although there is very little coating on the sample to make any conclusions with certainty.

APM01145 No interface is visible on the microscope image of the sample from APM01145, because no ceramic is present in the sample. The white areas in the image are where the epoxy has not fully impregnated the sample

APM01161 The interface between surface coating and the clay looks similar to that of APM00257 and seems to be well integrated.

APM14207 The layer seems to be well integrated with the clay. The image with fluorescent light indicates the presence of an organic layer, which is probably a layer of shellac (restoration) which fluoresces orange.

Table 7. Observations of Microscope Samples



Results of EDX Analysis

APM00257: Sample of Coating and Ceramic

4(1)

Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO Fe2O3 PbO

pt1 ceramic area 0,7 5,4 14,9 58,8 0,0 0,3 2,1 7,6 9,2 0,0

pt2 ceramic area 1,5 4,5 14,1 57,6 0,8 0,5 3,1 9,2 7,7 0,0

pt3 surface layer point 0,0 12,9 0,5 7,4 0,0 2,9 0,0 4,4 0,0 68,9



pt6 inclusion 0,0 0,0 0,0 100,0 0,0 0,0 0,0 0,0 0,0 0,0

pt7 inclusion 0,0 0,6 0,0 1,1 0,0 0,0 0,0 98,3 0,0 0,0

Figure 11. Back-scattered image of 4(1),

APM00257 (175x)

Figure 12. Microscope Image of the embedded

sample of APM00257



APM00277: Ceramic with a Small Amount of Coating

3(1)

Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO Fe2O3 PbO

pt1 Ceramic area 1,3 5,1 15,5 59,1 0,0 0,2 2,0 5,9 10,2 0,0

pt2 surface layer (bottom) area

0,0 29,6 1,3 6,0 0,0 1,0 0,0 49,7 0,0 12,5

pt3 surface layer (top) area

0,0 17,9 0,0 31,6 43,3 2,1 0,0 3,9 0,0 0,0

pt4 inclusion 0,0 1,5 2,3 8,1 0,0 0,0 0,0 0,8 86,4 0,9


APM00277 (250x)

Figure 14. Microscope Image of the

embedded sample of APM00277



Figure 16. Back-scattered image of

7(4), APM00394 (1500x)

APM00394: Ceramic with a Small Amount of Coating

7(1)

Na2O MgO Al2O3 SiO2 Cl K2O CaO TiO2 Fe2O3

pt1 Ceramic area 1,1 1,6 19,3 59,4 0,4 2,2 7,5 0,6 7,9

pt2 surface layer area 0,0 19,7 4,9 50,7 0,9 0,6 18,3 0,0 4,9

pt3 surface layer area 0,0 4,4 10,1 34,9 3,0 1,7 37,0 0,0 8,8

7(2)

Na2O MgO Al2O3 SiO2 Cl K2O

pt1 Ceramic area 1,5 2,0 18,3 59,5 0,0 2,0

pt2 surface layer area 0,0 21,4 4,7 51,6 1,2 0,0

7(3)

Na2O Al2O3 SiO2 S CaO Ba

pt1 Inclusion in ceramic 7,2 15,7 52,5 5,3 1,9 17,5

7(4)

MgO Al2O3 SiO2 Cl K2O CaO Fe2O3

pt1 surface layer point 24,5 4,6 56,1 0,7 0,0 8,6 5,4



Figure 15. Back-scattered image of

7(1), APM00394 (180x)





APM01145: Coating

9(1)

MgO Al2O3 SiO2 S Cl K2O CaO TiO2 Fe2O3

pt1 surface 0,0 41,1 56,8 0,7 0,0 0,0 0,0 1,4 0,0

pt2 coating 0,0 43,3 56,7 0,0 0,0 0,0 0,0 0,0 0,0

pt3 coating 0,0 16,6 83,4 0,0 0,0 0,0 0,0 0,0 0,0

pt4 coating 0,0 9,2 12,0 0,0 0,0 0,0 78,8 0,0 0,0

pt5 coating 2,5 28,2 54,3 0,0 0,0 5,0 1,5 2,2 6,4

pt6 coating 0,0 23,3 59,6 0,0 0,8 10,1 6,1 0,0 0,0


APM01145 (500x)


sample of APM01145



APM01161: Ceramic with a Small Layer of Coating

10(1)

Na2O MgO Al2O3 SiO2 Cl K2O CaO Fe2O3

pt1 ceramic point 0,0 15,5 9,7 26,0 0,0 1,4 42,4 4,9

pt2 ceramic area 1,5 4,6 14,1 43,2 0,0 2,8 26,0 7,8

pt3 ceramic area 2,1 3,0 13,7 50,3 0,6 2,7 20,7 6,7

pt4 ceramic area 3,6 3,6 12,3 61,9 0,9 1,1 7,7 8,9

pt5 surface layer area 0,0 0,0 6,6 18,1 1,7 0,0 73,7 0,0




APM01161 (160x)


sample of APM01161




APM14207 (650x)

APM14207: Sample of Coating and Ceramic

1(1)

Na2O MgO Al2O3 SiO2 P2O5 SO3 Cl K2O CaO TiO2 Fe2O3

pt1 ceramic 3,1 2,4 23,4 55,0 0,2 1,6 0,7 4,8 2,7 0,9 5,2

pt2 coating 0,0 0,3 39,5 57,1 0,0 0,8 0,4 0,0 1,4 0,1 0,4

pt3 surface of coating 0,0 1,1 29,2 34,2 3,0 13,4 1,6 1,5 14,7 0,0 1,3

pt4 inclusion 0,0 0,0 43,2 56,6 0,0 0,0 0,0 0,0 0,2 0,0 0,0

pt5 inclusion 0,0 0,0 10,0 89,9 0,0 0,0 0,1 0,0 0,0 0,0 0,0

1(2)

Al2O3 SiO2 CaO Cu2O

pt1 inclusion point 7,5 65,0 13,5 14,0

pt2 inclusion point 2,8 97,2 0,0 0,0

1(3)

Al2O3 SiO2

pt1 inclusion point 42,7 57,3


APM14207 (350x)




embedded sample of APM14207 in

Fluorescent Light



EDX Interpretation

The results from the EDX analysis can be found in table 8 and the results with spectra in

appendix V. The major elements are presented after having been normalised.

The coating layer on object APM00257 contains magnesium and silica and between 7,5 – 9

w% calcium oxide, suggesting the presence of clay mixed with chalk. This suggestion is

supported by a large calcium inclusion. In the back-scattered image of APM00257 (fig. 11)

one can see that the clay is not sintered and the presence of a chalk inclusion confirms that

the coating cannot have been fired. The silica inclusion could suggest the addition of sand

to the coating, but is more likely to be an accidental inclusion. Lead was measured on the

surface, which could have been from paint.

The ceramic body APM00277 contains iron-rich clay inclusions (fig. 13). The coating layer

contains magnesium (+/- 30%) and calcium oxide (+/- 50%), indicating the presence of

dolomite (CaMg(CO3)2), a mineral commonly found in chalk and limestone deposits. The

lower layer contains silica, magnesium and some lead, indicating the presence of talc

Mg₃Si₄O₁₀(OH)₂) and some lead.

The sample of APM00394 contained two areas in which surface coating is present (fig. 15).

On the left sample (measurement area 3), the coating contains aluminium and silica with

nearly 40 w% calcium suggesting a calcium-rich clay or clay mixed with chalk. The coating

sample on the right (measurement area 2) contains calcium oxide (+/- 20w%), magnesium

(20w%) and silica (fig. 16). This indicated the presence of talc. Silica inclusions are present

in the ceramic and the surface coating. Very small calcium inclusions (+/- 10µm) appear to

be present in the coating. The platelet structure of the clay particles as seen in figure 16

shows that the coating has not been fired.

The surface coating of the sample of APM01145 (fig. 18), is solely composed of aluminium

and silica. This shows the presence of a very pure clay and indicates that it is kaolinite

(Al2Si2O5(OH)4). In addition, some small calcium particles are present in the coating.

APM01161 is primarily composed of aluminium and silica and calcium oxide, suggesting a

calcium-rich clay (fig. 20). The surface coating has a very high w% (60 -70%) of calcium,

indicating the presence of a chalk layer. Some magnesium and silica are is also present,

indicating talc.

In APM14207 (fig. 22) there appears to be very little difference in the composition of the

ceramic and surface coating, both primarily containing of aluminium and silica. Because the

sample of the coating is so small, it is difficult to be certain about its morphology and

whether the slip coating is fired or not. The sample does not appear to have the platelet

structure of unfired clay (fig. 23).



Inventory Number

Conclusions Regarding the Nature of the Coating from the SEM-EDX Results

APM00257 Chalk mixed with clay. Unfired

APM00277 Top layer: dolomite-rich chalk, lower layer: talc containing lead. Unfired

APM00394 Talc and chalk. Unfired

APM01145 Pure kaolinite-rich clay, could be kaolin. Some small calcium particles. Fired

APM01161 Chalk layer, some talc present. Unfired

APM14207 Kaolinite-rich coating

Table 8. Conclusions Regarding the Nature of the Coating from the SEM-EDX Results



4. Conclusions from the Analysis

In this chapter the results and interpretations on each of the object has been used to come

to a conclusion on the composition of each of the surface coatings and to get an overview

of the differences in surface loss. This information has been analysed together to come to

a conclusion on whether the composition of the surface coating influences the

susceptibility to loss.

APM00257

pXRF results of the surface coating on APM00257 showed the presence of calcium

carbonate, which suggested that a chalk layer is present. Calcite was also detected during

analysis with XRD. The data from SEM-EDX analysis showed the presence of clay as well as

chalk, but the morphology suggests it is unfired. Based on these results it appears that the

surface coating on APM00257 is chalk mixed with clay.

The coating appears well attached to the ceramic. Optical analysis suggested that the

surface coating seemed not to have detached but to have been worn off, suggesting good

adhesion. The coating however crumbled during sampling suggesting it has a friable

structure as would be expected on an unfired, chalk-based coating. The fact that seventy

per cent of the surface coating is still present on the object, seems to be partly due to the

encrustation layer which may have protected the surface coating. The coating appears

surprisingly well bonded with the surface, but is friable.

APM00277

pXRF analysis of the coating on APM00277 showed the presence of calcium carbonate,

which suggested that it is a chalk layer. XRD results showed the presence of possibly talc

and diopside together with clay minerals. SEM-EDX analysis has shown that in some areas

talc or dolomite are present.

The coating appears to be well integrated to the ceramic. The coating crumbled during

sampling and was very friable. Seventy per cent of the coating still remains on the object

and is only missing from the more protruding areas. The coating does not seem to have

detached but to have been mechanically removed. This suggests that the loss of the coating

has mainly occurred due to cleaning, but that the chalk, while well adhered to the surface,

was very friable and susceptible to mechanical damage.



APM00394

pXRF results of the surface coating on APM00394 showed the presence of calcium

carbonate, which suggests that chalk may be present. XRD results confirmed the presence

of calcite. SEM-EDX analysis showed that the coating contains clay with up to 30% calcium

oxide silica, magnesium and calcium, indicating a coating layer containing talc and/or chalk.

The microscopic and back-scattered images suggest that the coating is well adhered to the

ceramic. An encrustation layer is present all over the surface of the object. Assuming that

the coating is present underneath the encrustation layer, ninety per cent of the coating

remains. On sampling, the coating was very friable. A shellac layer was possibly applied as

consolidation restoration treatment to prevent loss of the surface coating.

APM01145

pXRF results of the surface coating on APM01145 suggested the presence of a slip layer.

XRD results showed the presence of calcite, which was probably the encrustation layer.

SEM-EDX analysis showed that the coating is primarily composed of aluminium and silica,

suggesting it is a pure kaolinite-rich clay and possibly kaolin. The coating appears to be

fired.

The coating flaked off during sampling, attached to a small layer of ceramic. This, together

with the analysis from the microscope images and back-scattered images shows that the

coating is very well attached to the surface which one would expect with a fired-on slip.

Optical analysis suggested that traces of mechanical cleaning are present on the object.

This would suggest that the fact that only ten per cent of the coating remains, is mainly due

to severe cleaning. However, the way the damage pattern showed both that the coating

was worn as well as fresh breaks which suggest detachment of the coating suggesting that

the fired slip was not well matched with the ceramic body and stress formed at the

interface.



APM01161

pXRF results of the surface coating on APM01161 suggested a mixture of chalk and clay or

calcium-rich clay. XRD results showed the presence of calcite. SEM-EDX analysis showed

that it had a very high w% of calcium oxide, indicating the presence of a chalk-rich including

talc.

The coating did not appear friable during sampling and seemed to be well attached to the

ceramic. This confirms what was seen during optical analysis which found that the coating

was lost due to mechanical action and had not detached. Sixty per cent of the coating

remains on this object. Due to the presence of pigment on the object, it is possible that the

object was less severely cleaned. This coating seems to be relatively stable.

APM14207

pXRF results of the surface coating on APM14207 suggested the presence of a calcium-rich

clay layer. XRD results showed the presence of kaolinite. SEM-EDX confirmed that the

coating primarily contained aluminium and silicate, indicating a kaolinite-rich or kaolin clay

coating that appears to be fired on. The composition of the clay and coating was similar,

the clay containing a little more calcium.

The surface coating is well integrated with the clay and a small sample detached together

with a piece of ceramic while handling. The coating does not seem to be worn, but in places

where coating is missing, fresh breaks are present which suggests the coating has detached.

As it is a fired slip susceptibility for detachment could be related to production. Seventy

per cent of the layer still remains and pigments are present on many parts of the surface

coating, which would suggest that the object has not been severely cleaned. The surface

coating did seem to detach and one flake with ceramic detached during handling. The

(fired) slip is well bonded at the interface.



Conclusion

The question that has been considered in this research was ‘In how far does the

composition of the surface coating on ancient Greek terracotta figures influence the

susceptibility of the coating layer?’. The research was focused on a case study of six

Boeotian and Tarentian terracotta objects from the Allard Pierson Museum, dating

between 400 and 200BC.

Since nothing is known about what happened to the objects between being excavated and

moving to the museum, it is impossible to know to what conditions and treatment the

objects may have been subjected. It can be assumed that most objects have been cleaned

at some point, which was commonly done during excavation. On one object (APM01145),

traces of mechanical cleaning appear to be visible. Deep scratches are visible that were

most likely created by hard brushes. It is therefore very likely that severe cleaning was the

main cause of the abrasion of the surface coatings of the objects. The fact that the coating

is generally missing from the higher areas and is best preserved in the deeper areas

supports the idea that the slip was removed by mechanical cleaning. The burial

environment could have influenced deterioration. Wet or acidic conditions would

especially affect unfired coatings. However, that would affect the whole surface and, as has

been explained, the localized loss suggests mechanical cleaning.

Optical and instrumental analysis have shown that a variety of coatings are present on the

ancient Greek terracotta case study objects researched. This is in contrast to what was

expected before conducting the analyses. It is clear that Knoop was right when he stated

in 1987 that the term ‘slip’ refers to any surface coating.

On four objects (APM00257, APM00277, APM00394 and APM01161) the coating was found

to primarily consist of calcium and is presumed to be chalk-based. This would have been

applied after firing. On two of the Tarentian objects (APM01145 and APM14207) the

coating is a kaolite-rich slip coating. The chalk-rich coating cannot have been fired and must

have been applied after firing. The two slip coatings appear to have been fired-on. None of

these objects were found to have un-fired kaolin coatings as mentioned in recent

research unless one includes the clay coatings mixed with chalk. Further XRD analysis of

the two objects with slip should be able to confirm that the slip on the two objects

researched is indeed fired.

Optic analysis of the surface coatings showed a difference in the way the coatings had come

off the ceramic surface. On the objects with a calcium-rich coating, where the surface layer

had been worn-off, coating material remained on the surface, suggesting a good

attachment between the coating and the ceramic. The kaolin-rich fired-on slip seemed to

have pulled-away from the ceramic surface, suggesting that, while this type of coating has

a better bond at the interface, its detachment may be related to release of tension between

the two clay materials (the slip and the object).



The morphology of kaolin-rich fired-on slip coatings and calcium-rich coatings is shown to

differ. The unfired calcium-rich coatings crumbled easily during sampling, appearing to be

more friable than the kaolin-rich fired-on slip coatings, which seemed to be more compact,

making it easy to remove microscopic samples in one piece. The difference in morphology

was confirmed in the SEM back-scattered images.

The Boeotia objects were solely decorated with a calcium-rich coating, apparently chalk-

based. Two out of three objects from Taranto had a kaolinite-rich or fired-slip coating and

the third object had a calcium-rich or chalk-based coating. While these results suggest

differences between production centres, the sample set is too small and a larger study

group is necessary to fully support this conclusion.

Surfaces with an encrustation layer or where pigments are still present have retained more

of the original coating. The reason for this appears to be that the encrustation layer has

protected the surface coating during mechanical cleaning. The objects which still have

traces of the original pigment decoration may have been cleaned less severely to preserve

the pigments therefore preserving more surface coating. Past treatment may also play a

role. On one object (APM14207) where it appears that shellac was applied to the surface,

a large amount of slip remains.

This research has shown that a surprising variety of coatings are found on ancient Greek

terracotta objects from Boeotia and Taranto. Information has been gained on both the

composition and morphology of these coatings. It appears that unfired chalk-based

coatings are not necessarily more susceptible to damage, which is surprising. The fired-on

slip seemed susceptible to different kinds of damage more related to the firing process.

While this research suggests that the composition of the surface coating influences the way a surface coating detaches, the small size of the object set and the samples taken and analysed means that it is not possible to be certain of this. For this, further research, including a larger case study set is needed.



English Summary

This thesis discusses the research undertaken into the possible reasons for the variation in

percentages of loss of the coatings on a group of ancient Greek terracotta objects, the main

research question being ‘In how far does the composition of the surface coating on ancient

Greek terracotta figures influence the susceptibility of the coating layer to damage?’.

Surface coatings, often referred to as ‘slip’ were used to provide a light-coloured base for

further decoration with pigments.

In order to select a representative test set of six objects, pXRF analysis was conducted on a

preselected group of fourteen ancient Greek terracotta objects with a coating from the

collection of the Allard Pierson Museum. Six terracotta objects with varying conditions of

surface decoration were selected. Three originate from Boeotia (Greece) and three are

from Taranto (now Italy). All objects date between the fourth and the second century BC.

Optical and instrumental analysis, including Hirox optical microscopy, XRD and SEM-EDX

was undertaken on the selected six objects in order to analyse and compare the condition,

morphology and composition of each of the surface coatings and to determine what type

of coating is present on each of the objects.

Optical analysis revealed traces of mechanical cleaning that were most likely created by

hard brushes, which suggests that severe cleaning was a major cause of the abrasion of the

surface coatings of the objects. Both optical and instrumental analysis showed that a

variety of coatings were present on the case study objects. The terracottas produced in

Boeotia were solely decorated with a calcium-rich coating, apparently chalk-based, that

was applied after firing. Two out of three objects from Taranto had a kaolinite-rich slip

coating that was fired-on. The third Taranto object had a calcium-rich or chalk-based

coating similar to the coatings on the Greek objects.

Optical analysis of the surface coatings showed that, while the damage of the coating on

the objects with a calcium-rich coating was from abrasion, the nature of the abrasion

suggests a good attachment between the coating and the ceramic. The kaolin-rich fired-on

clay slip was seen to detach in a different way, suggesting that, while this type of coating

has a better bond at the interface, it may be under tension due to differential contraction

and expansion. The unfired calcium-rich coatings crumbled during sampling, showing that

is more friable than the kaolin-rich fired-on slip coatings, which has a more compact

structure. This was confirmed in the SEM back-scattered images.

This research made clear that a variety of coatings exist on ancient Greek terracotta objects

from Boeotia and Taranto. It appears that the unfired chalk-based coatings are surprisingly

well bonded to the ceramic, the loss being mainly due to their morphology making them

friable. The fired-on slip seems to be affected by a different damage pattern influenced by

tensions in the two clay materials.



While this research suggests that the composition of the surface coating influences the way a surface coating detaches, the small size of the object set means that this cannot be claimed for certain. In order to confirm and better understand this, further research, including a larger case study group is needed.



Dutch Summary

Deze scriptie bespreekt onderzoek dat is uitgevoerd naar de mogelijke redenen voor de

variatie in de percentages van het verlies van coating op antieke Griekse terracotta

objecten. Daarmee probeert het specifiek de onderzoeksvraag te beantwoorden: ‘In

hoeverre heeft de compositie van de oppervlaktecoating op terracotta figurines uit de

Griekse oudheid invloed op de vatbaarheid van de coating?’ Coatings op het oppervlak van

objecten, ook wel ‘slib’ genoemd, werden gebruikt om een lichtgekleurd oppervlak te

creëren voor verdere decoratie met pigmenten.

Om een representatieve testset van zes objecten te kunnen selecteren is er een pXRF

analyse uitgevoerd op een voorgeselecteerde groep van veertien antieke Griekse

terracotta objecten met een coating van de collectie van het Allard Pierson Museum. Zes

terracotta objecten met variërende condities in oppervlaktecoating werden geselecteerd.

Drie objecten zijn afkomstig uit Boeotië (Griekenland) en drie komen uit Taranto (huidig

Italië). Alle objecten dateren tussen de vierde en tweede eeuw voor Christus. Verder is er

optische en instrumentele analyse, zoals Hirox optische microscopie, XRD en SEM-EDX

uitgevoerd op de geselecteerde zes objecten om de aard en conditie van elk van de

oppervlaktecoatings te registreren en te vergelijken evenals om vast te stellen wat voor

type coating aanwezig is op elk van de objecten in dit onderzoek.

Optische analyse heeft sporen van mechanische reiniging onthuld op object APM01145 die

hoogstwaarschijnlijk gecreëerd zijn door harde borstels, wat laat zien dat hevig

schoonmaken heeft geleid tot op zijn minst een deel van het afslijten van de

oppervlaktecoating van de objecten. In aanvulling, optische en instrumentele analyse

hebben laten zien dat een verscheidenheid aan coatings aanwezig is op de Griekse

terracotta case study objecten. De terracotta’s die geproduceerd zijn in Boeotië waren

alleen versierd met een calciumrijke coating, blijkbaar op kalk basis. Twee van de drie

objecten uit Taranto hadden een kaoliniet-rijke of gebakken sliblaag. Het derde object had

een calciumrijke of op kalk gebaseerde coating.

Optische analyse van de oppervlaktecoating liet zien dat op de objecten met een

calciumrijke coating de coating afgesleten lijkt, wat suggereert dat er een goede hechting

is tussen de coating en het aardewerk. De kaoliniet-rijke gebakken slib leek eraf te komen,

wat suggereert dat dit type coating een betere hechting heeft op het raakvlak, maar dat er

spanning is door verschil in inkrimping en uitzetting. Ook de ongebakken calciumrijke

coatings verbrokkelden tijdens het samplen, wat laat zien dat deze laag brosser is dan de

kaolienrijke gebakken sliblaag, welke een compactere structuur heeft. Dit werd bevestigd

met de SEM back-scattered afbeeldingen.

Dit onderzoek heeft laten zien dat een variëteit aan coatings aanwezig is op antieke Griekse

terracotta objecten uit Boeotië en Taranto. Het lijkt erop dat ongebakken coatings op

kalkbasis niet persé vatbaarder zijn voor beschadiging, wat verrassend is. Gebakken slib



leek vatbaar voor verschillende soorten schade beïnvloedt door spanningen in de twee

kleimaterialen.

Alhoewel dit onderzoek suggereert dat de compositie van de oppervlaktecoating invloed

heeft op de manier waarop een oppervlaktecoating loslaat, is het niet mogelijk om dit met

zekerheid vast te stellen vanwege de kleine objectset. Hiervoor zal verder onderzoek nodig

zijn, inclusief een grotere case study groep.



List of Figures

Figures have been made by the author, unless stated otherwise.

The back-scattered images and the microscope images of the embedded samples were taken by

Luc Megens (RCE)

Figure 1. Map depicting Taranto (modern Italy) and Boeotia (Greece). (Source: Google Maps. “Taranto and Boeotia” Accessed June 5, 2019.

“https://www.google.com/maps/place/Boeotia,+Greece/@38.7971366,19.5193164,627905m/data=!3m1!1e3!4m5!3m4!1s0x14a0f4072069dc91:0x300bd2ce2b980e0!8m2!3d38.3663664!4d23.0965064?hl=en)

Figure 2. Standing woman with chiton and himation (APM00257) 175h x 60w

Figure 3. Head of woman (APM00277) 90h x 58w

Figure 4. Standing woman with hand on side (APM00394) 215h x 85w

Figure 5. Lower part of walking woman (APM01145) 190h x 125w

Figure 6. Eros (APM01161) 210h x 85w

Figure 7. Incense burner (APM14207) Side A 80h x 68w

Figure 8. Hirox Digital Microscope Image of APM14207 encrustation and coating (20x)

Figure 9. Hirox Digital Microscope Image of APM01161 cheek (20x)

Figure 10. Hirox Digital Microscope Image of APM01145 brush marks (20x)

Figure 11. Microscope Image of the embedded sample of APM00257

Figure 12. Back-scattered image of 4(1), APM00257 (175x)













Figure 25. Microscope Image of the embedded sample of APM14207 in Fluorescent Light



Appendix I

Figure I.1. Standing woman with chiton and himation (APM00257) Front

Figure I.2. Standing woman with chiton and himation (APM00257) Back

Figure I.3. Standing woman with chiton and himation (APM00257) Bottom

Figure I.4. Head of woman (APM00277) Front

Figure I.5. Head of woman (APM00277) Back

Figure I.6. Head of woman (APM00277) Bottom

Figure I.7. Standing woman with hand on side (APM00394) Front

Figure I.8. Standing woman with hand on side (APM00394) Back

Figure I.9. Standing woman with hand on side (APM00394) Bottom

Figure I.10. Lower part of walking woman (APM01145) Front

Figure I.11. Lower part of walking woman (APM01145) Back

Figure I.12. Lower part of walking woman (APM01145) Bottom

Figure I.13. Eros (APM01161) Front

Figure I.14. Eros (APM01161) Back

Figure I.15. Eros (APM01161) Bottom

Figure I.16. Incense burner (APM14207) Side A

Figure I.17. Incense burner (APM14207) Side B

Figure I.18. Incense burner (APM14207) Side C

Figure I.19. Incense burner (APM14207) Side D

Figure I.20. Incense burner (APM14207) Bottom

Figure I.21. Incense burner (APM14207) Top



Appendix II

Figure II1. Image of Object APM00257 taken by the Allard Pierson Museum.

Source: Allard Pierson Museum Archeologische Collectie, December 2004. Accessed

February 1, 2019. http://dpc.uba.uva.nl/archeologischecollectie.

Figure II2. Image of Object APM00257

Source: C.W. Lunsingh Scheurleer, Catalogus Eener Verzameling Egyptische, Grieksche,

Romeinsche En Andere Oudheden (S-Gravenhage: Nijgh & Van Ditmar, 1909), plate XXI.

Figure II3. Image of Object APM00257

Source: C.W. Lunsingh Scheurleer, Catalogus Der Tentoonstelling Van Grieksche En

Romeinsche Kunstnijverheid (Rotterdam: Academie Van Beeldende Kunsten En

Technische Wetenschappen, 1911), 80i.










Figure II7. Images of Object APM01161 taken by the Allard Pierson Museum.



Figure II8. Images of Object APM14207 taken by the Allard Pierson Museum.



Figure II9. Images of Object APM14207

Source: Griekse Terracotta's: Uit De Collectie Van Het Haags Gemeentemuseum (Den

Haag: Haags Gemeentemuseum, 1986), 56-57.



Appendix III

Figure III.1. Indicating Coating (No Colour)/ No Coating (Red) APM00257 Front

Figure III.2. Hirox Digital Microscope Image of APM00257 coating nose (20x)

Figure III.3. Hirox Digital Microscope Image of APM00257 blue pigment (80x)

Figure III.4. Hirox Digital Microscope Image of APM00257 encrustation layer in between

ridges (20x)

Figure III.5. Indicating Coating (No Colour)/ No Coating (Red) APM00257 Back




Figure III.9. Hirox Digital Microscope Image of APM00277 coating cheek (20x)

Figure III.10. Hirox Digital Microscope Image of APM00277 coating neck (120x)



Figure III.13. Hirox Digital Microscope Image of APM00394 nose (20x)

Figure III.14. Hirox Digital Microscope Image of APM00394 stomach (20x)

Figure III.15. Hirox Digital Microscope Image of APM00394 stomach (120x)



Figure III.18. Hirox Digital Microscope Image of APM01145 folds (20x)

Figure III.19. Hirox Digital Microscope Image of APM01145 left leg (20x)

Figure III.20. Hirox Digital Microscope Image of APM01145 folds (20x)

Figure III.21. Hirox Digital Microscope Image of APM01145 anckle (60x)

Figure III.22. Hirox Digital Microscope Image of APM01145 brush marks (20x)



Figure III.25. Hirox Digital Microscope Image of APM011461 head coating and pigment

(120x)

Figure III.26. Hirox Digital Microscope Image of APM01161 nose (20x)

Figure III.27. Hirox Digital Microscope Image of APM01161 cheek (20x)



Figure III.28. Hirox Digital Microscope Image of APM01161 breast (160x)

Figure III.29. Hirox Digital Microscope Image of APM01161 wing encrustation, pigment

and coating (20x)


Figure III.31. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side A

Figure III.32. Hirox Digital Microscope Image of APM14207 encrustation and coating (20x)

Figure III.33. Hirox Digital Microscope Image of APM14207 encrustation and coating (80x)

Figure III.34. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side B

Figure III.35. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side C

Figure III.36. Hirox Digital Microscope Image of APM14207 coating (20x)

Figure III.37. Hirox Digital Microscope Image of APM14207 coating (100x)

Figure III.38. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side D

Figure III.39. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Top

Figure III.41. Hirox Digital Microscope Image of APM14207 pigments (140x)

Figure III.40. Hirox Digital Microscope Image of APM14207 pigments (20x)



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Acknowledgements

I would first like to thank my thesis supervisor Kate van Lookeren Campagne – Nuttall from

the University of Amsterdam. She was always ready to answer any questions I had about

my research or writing, had lots of patience during the entire process and always made

time to assist or help when needed and to give elaborate feedback.

Furthermore, I would like to thank Luc Megens from the Rijksdienst voor het Cultureel

Erfgoed (RCE) for conducting the instrumental analyses needed for this research as well as

for helping with the interpretation of the results. Without his elaborate knowledge as well

as his genuine interest in this research and his access to a Rubik’s Cube during analysis, this

research could not have been successfully conducted.

I would also like to thank René van Beek, conservator of the Classical World at the Allard

Pierson Museum for his help with finding a suitable research topic and for his assistance

during the object selection and for making the objects available for research.

Finally, I would like to thank Professor Maarten van Bommel and Professor Ella Hendriks

from the University of Amsterdam for their advice during this research.



Appendix I: Images

Figure I.2. Standing woman with chiton and

himation (APM00257) Back

Figure I.1. Standing woman with chiton and himation

(APM00257) Front

Figure I.3. Standing woman with chiton and himation

(APM00257) Bottom



Figure I.5. Head of woman (APM00277) Back

Figure I.4. Head of woman (APM00277) Front

Figure I.6. Head of woman (APM00277) Bottom



Figure I.8. Standing woman with hand on side

(APM00394) Back

Figure I.7. Standing woman with hand on side

(APM00394) Front

Figure I.9. Standing woman with hand on side (APM00394) Bottom



Figure I.10. Lower part of walking woman

(APM01145) Front

Figure I.11. Lower part of walking woman

(APM01145) Back

Figure I.12. Lower part of walking woman (APM01145) Bottom



Figure I.14. Eros (APM01161) Back

Figure I.13. Eros (APM01161) Front

Figure I.15. Eros (APM01161) Bottom



Figure I.16. Incense burner (APM14207) Side A

Figure I.17. Incense burner (APM14207) Side B

Figure I.18. Incense burner (APM14207) Side C

Figure I.19. Incense burner (APM14207) Side D

Figure I.20. Incense burner (APM14207) Bottom



Figure I.21. Incense burner (APM14207) Top



Appendix II: Images from Museum Database and Literature

Figure II.1. Standing woman with chiton and himation

(APM00257) taken by the Allard Pierson Museum.

Source: Allard Pierson Museum Archeologische Collectie,

December 2004. Accessed February 1, 2019.

http://dpc.uba.uva.nl/archeologischecollectie.

Figure II.2. Standing woman with chiton and himation (APM00257)

Source: C.W. Lunsingh Scheurleer, Catalogus Eener

Verzameling Egyptische, Grieksche, Romeinsche En

Andere Oudheden (S-Gravenhage: Nijgh & Van Ditmar,

1909), plate XXI.

Figure II.3. Standing woman with chiton and himation (APM00257)

Source: C.W. Lunsingh Scheurleer, Catalogus Der

Tentoonstelling Van Grieksche En Romeinsche

Kunstnijverheid (Rotterdam: Academie Van Beeldende

Kunsten En Technische Wetenschappen, 1911), 80i.



Figure II.6. Standing woman with hand on side (APM00394) taken by the Allard Pierson

Museum. Source: Allard Pierson Museum Archeologische Collectie, December 2004.

Accessed February 1, 2019. http://dpc.uba.uva.nl/archeologischecollectie.

Figure II.4. Head of woman (APM00277) taken by the Allard Pierson Museum. Source: Allard Pierson Museum Archeologische Collectie,

December 2004. Accessed February 1, 2019. http://dpc.uba.uva.nl/archeologischecollectie.

Figure II.5. Lower part of walking woman (APM01145) taken by the Allard Pierson Museum.

Source: Allard Pierson Museum Archeologische Collectie, December 2004. Accessed February 1,

2019. http://dpc.uba.uva.nl/archeologischecollectie.



Figure II.7. Eros (APM01161) taken by the Allard Pierson Museum. Source: Allard Pierson Museum Archeologische Collectie, December 2004. Accessed February 1, 2019.




Figure II.8. Incense burner (APM14207) taken by the Allard Pierson Museum. Source: Allard Pierson Museum Archeologische Collectie, December 2004. Accessed February 1, 2019.


Figure II.9. Incense burner (APM14207) Source: Griekse Terracotta's: Uit De Collectie Van Het Haags Gemeentemuseum (Den Haag: Haags

Gemeentemuseum, 1986), 56-57.



Appendix III: Indicating Coating Layer, Hirox Images, XRD

Measurement Points and Location of SEM-EDX Samples


XRD Measurement Point (Blue dot)

B Figure III.3. Hirox Digital Microscope

Image of APM00257 blue pigment

(80x)

C Figure III.4. Hirox Digital Microscope

Image of APM00257 encrustation layer

in between ridges (20x)

A Figure III.2. Hirox Digital Microscope

Image of APM00257 coating nose (20x)

C

B

A



Figure III.5. Indicating Coating (No Colour)/ No Coating (Red) APM00257 Back Location SEM-EDX Sample (Green Square)




And XRD Measurement Point (Blue dot) Location SEM-EDX Sample (Green Square)




Image of APM00277 coating neck

(120x)




Image of APM00277 coating cheek

(20x)

C

B

A




And XRD Measurement Point (Blue dot) Location SEM-EDX Sample (Green Square)


Image of APM00394 nose (20x)


Image of APM00394 stomach (20x)


Image of APM00394 stomach (120x)

B

A




Image of APM01145 left leg (20x)


Image of APM01145 folds (20x)


Image of APM01145 folds (20x)

D Figure III.21. Hirox Digital Microscope

Image of APM01145 anckle (60x)


And XRD Measurement Point (Blue dot)

E Figure III.22. Hirox Digital Microscope

Image of APM01145 brush marks (20x)

A

D

B

C

E




And XRD Measurement Point (Blue dot)


Image of APM011461 head coating and

pigment (120x)

D Figure III.28. Hirox Digital Microscope

Image of APM01161 breast (160x)


Image of APM01161 cheek (20x)


Image of APM01161 nose (20x)

E Figure III.29. Hirox Digital Microscope

Image of APM01161 wing encrustation,

pigment and coating (20x)

C B

D

A

E



Figure III.31. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side A

Location SEM-EDX Sample (Green Square)

Figure III.34. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side B


Image of APM14207 encrustation and

coating (20x)


Image of APM14207 encrustation and

coating (80x)

A

B



Figure III.35. Indicating Coating (No Colour)/ No Coating (Red)

APM14207 Side C

Figure III.38. Indicating Coating (No Colour)/ No Coating (Red) APM14207 Side D


Image of APM14207 coating (100x)


Image of APM14207 coating (20x)

A



Figure III.39. Indicating Coating (No Colour)/ No Coating (Red)

APM14207 Top


Image of APM14207 pigments (20x)


Image of APM14207 pigments (140x)

A



Appendix IV: XRD Results of Case Study Group

Conclusion

Object Number Most Significant Crystalline Phase(s)

APM14207 kaolinite

APM01161 calcite

APM01145 calcite (probably thin layer), possibly also diopside

APM00394 calcite

APM00277 possibly talc and diopside (clay minerals)

APM00257 calcite



Results

600

APM00257

500

400

300

200

100

0

16 20 30 40 50

2-Theta - Scale APM00257 faded slip - File: APM00257faded_slip_001.raw - Type: 2Th alone - Start: 15.333 ° - End: 59.241 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 15.333 ° - Theta

Operations: Displacement 0.062 | Background 0.081,0.100 | Import

00-005-0586 (*) - Calcite, syn - CaCO3 - Y: 115.13 % - d x by: 1. - WL: 1.54184 - Rhombo.H.axes - a 4.98900 - b 4.98900 - c 17.06200 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - R-3c (167) - 6 - 36

00-046-1045 (*) - Quartz, syn - SiO2 - Y: 12.66 % - d x by: 1. - WL: 1.54184 - Hexagonal - a 4.91344 - b 4.91344 - c 5.40524 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - P3221 (154) - 3 - 113.010 - I/

Lin

(C

ou

nts

)

d=

5.6

83

74

d=

4.7

20

13

d=

4.5

75

48

d=

4.2

22

94

d=

3.8

41

46

d=

3.5

86

08

d=

3.3

46

24

d=

3.0

30

85

d=

2.8

82

37

d=

2.8

46

90

d=

2.6

85

16

d=

2.5

85

11

d=

2.4

89

09

d=

2.3

73

94

d=

2.2

81

67

d=

2.2

18

69

d=

2.1

59

51

d=

2.1

24

72

d=

2.0

91

72

d=

1.9

80

08

d=

1.9

25

62

d=

1.9

11

03

d=

1.8

73

58

d=

1.8

17

25

d=

1.6

23

43

d=

1.6

03

51

XRD Results of a Measurement on APM00257, Created by Luc Megens (RCE Amsterdam)



APM000277

400

300

200

100

0

16 20 30 40 50 60

2-Theta - Scale APM000277 - File: APM000277_001.raw - Type: 2Th alone - Start: 16.000 ° - End: 61.800 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 16.000 ° - Theta: 19.450 ° - Chi: 4.

Operations: Background 0.081,0.100 | Import

APM000277 - File: APM000277_002.raw - Type: 2Th alone - Start: 16.000 ° - End: 61.800 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 16.000 ° - Theta: 19.450 ° - Chi: 4.


00-013-0558 (I) - Talc-2M - Mg3Si4O10(OH)2 - Y: 38.83 % - d x by: 1. - WL: 1.54184 - Monoclinic - a 5.28700 - b 9.15800 - c 18.95000 - alpha 90.000 - beta 99.500 - gamma 90.000 - Base-centered - C2/c (15) - 4 -

00-041-1370 (*) - Diopside - Ca(Mg,Al)(Si,Al)2O6 - Y: 42.45 % - d x by: 1. - WL: 1.54184 - Monoclinic - a 9.73200 - b 8.86700 - c 5.27870 - alpha 90.000 - beta 105.920 - gamma 90.000 - Base-centered - C2/c (15) - 00-

046-1045 (*) - Quartz, syn - SiO2 - Y: 13.97 % - d x by: 1. - WL: 1.54184 - Hexagonal - a 4.91344 - b 4.91344 - c 5.40524 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - P3221 (154) - 3 - 113.010 - I/

00-005-0586 (*) - Calcite, syn - CaCO3 - Y: 89.00 % - d x by: 1. - WL: 1.54184 - Rhombo.H.axes - a 4.98900 - b 4.98900 - c 17.06200 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - R-3c (167) - 6 - 367.

Lin

(C

ou

nts

)

d=

5.4

27

94

d=

5.2

46

27

d=

4.7

95

99

d=

4.0

07

96

d=

3.9

11

34

d

=3.8

23

31

d

=3.7

54

17

d

=3.6

82

12

d=

3.5

49

32

d=

3.3

97

75

d=

3.3

37

90

d=

3.1

21

16

d=

3.0

38

10

d

=2.9

94

28

d

=2.9

47

81

d=

2.7

38

57

d=

2.6

02

49

d=

2.4

85

45

d=

2.4

10

74

d=

2.3

12

58

d=

2.2

81

39

d=

2.2

14

57

d=

2.0

97

15

d=

2.0

39

95

d=

1.9

81

34

d=

1.9

52

88

d=

1.9

27

51

d=

1.8

95

56

d=

1.8

48

09

d=

1.7

35

77

d=

1.6

64

28

d=

1.6

18

08

d=

1.5

89

59

d=

1.5

64

15




APM000394

300

200

100

0

16 20 30 40 50 60

2-Theta - Scale APM000394 - File: APM000394_001.raw - Type: 2Th alone - Start: 15.876 ° - End: 61.692 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 15.876 ° - Theta: 19.450 ° - Chi: 4.

Operations: Displacement 0.115 | Background 0.081,0.100 | Import

00-005-0586 (*) - Calcite, syn - CaCO3 - Y: 118.72 % - d x by: 1. - WL: 1.54184 - Rhombo.H.axes - a 4.98900 - b 4.98900 - c 17.06200 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - R-3c (167) - 6 - 36


Lin

(C

ou

nts

)

d=

5.4

71

35

d=

5.3

08

65

d=

4.9

14

95

d=

4.5

52

24

d=

4.0

23

50

d=

3.3

36

89

d=

3.0

20

81

d=

2.8

34

99

d=

2.6

82

78

d=

2.6

34

11

d

=2.6

12

49

d=

2.4

85

53

d=

2.2

76

99

d=

2.1

70

95

d=

2.1

29

29

d=

2.0

87

84

d=

2.0

17

01

d=

1.9

77

08

d=

1.9

05

31

d=

1.8

68

10

d=

1.8

21

46

d=

1.7

48

79

d=

1.7

33

15

d=

1.6

97

18

d=

1.6

20

55

d=

1.5

99

25

d=

1.5

19

35




1100

1000

900

800

700

600

500

400

300

200

100

0

16 20 30 40 50 60

2-Theta - Scale APM01145 - File: APM01145_slip_001.raw - Type: 2Th alone - Start: 15.400 ° - End: 62.400 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 15.400 ° - Theta: 19.450 ° - Chi:


APM01145 - File: APM01145_ceramic_001.raw - Type: 2Th alone - Start: 15.400 ° - End: 62.400 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 15.400 ° - Theta: 19.450 ° -



00-005-0586 (*) - Calcite, syn - CaCO3 - Y: 31.17 % - d x by: 1. - WL: 1.54184 - Rhombo.H.axes - a 4.98900 - b 4.98900 - c 17.06200 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - R-3c (167) - 6 - 367. 00-

041-1370 (*) - Diopside - Ca(Mg,Al)(Si,Al)2O6 - Y: 30.06 % - d x by: 1. - WL: 1.54184 - Monoclinic - a 9.73200 - b 8.86700 - c 5.27870 - alpha 90.000 - beta 105.920 - gamma 90.000 - Base-centered - C2/c (15) -

APM01145 Li

n (

Co

un

ts)

d=

5.6

69

54

d=

5.5

11

74

d=

5.3

90

65

d=

5.2

04

26

d=

5.0

57

71

d=4.

43d 9

=54 5

.4839

4

d=

4 d.3 =

0 43 .23 7

8 72

0

d=

4.2

39

65

d=

3.8

63

56

d=

3.5

98

34

d=

3.5

84

07

d=

3.3

56

91

d=

3.3

44

41

d=

3d.2=

031.2

0233

74

d=

3.0

4d 0= 4

3 0.0

47

41

d=

2.9

91

42

d=

2.7

22

38

d

=2

.64

14

9

d=

2.5

92

42

d=

2.5

52

01

d=

2.5

23

65

d=

2.5

00

15

d=

2.4

5d0=

622.4

55

62

d=

2.3

75

29

d=

2.3

36

46

d= d

2 =.

9 .28 94 4

1 21

d=

2.2

39

14

d=

2.2

21

27

d= d

2 =. 21

.3 18 3

5 60 6

3

d=d

2=.2 1

. 019129

042

d=

2.0

49

10

d=

2.0

10

28

dd == 1

1 .9.

9 36 9

4 56

d=

1.9

21

33

d=

1.8

77

79

d=

1 d. =8

12.6 8

7 23 1

87

d=

1.8

07

26

d=

1.7

63

14

d=

1.7

36

25

d d= =1 1. .6 67 61 43 63 4

d=

1.4

92

42




APM01161 foot

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

33 40 50 60 70

2-Theta - Scale APM01161 foot - File: APM01161_foot_001.raw - Type: 2Th alone - Start: 32.600 ° - End: 78.300 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 32.600 ° - Theta: 27.725 ° -


00-046-1045 (*) - Quartz, syn - SiO2 - Y: 354.56 % - d x by: 1. - WL: 1.54184 - Hexagonal - a 4.91344 - b 4.91344 - c 5.40524 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - P3221 (154) - 3 - 113.010 - I

00-005-0586 (*) - Calcite, syn - CaCO3 - Y: 97.86 % - d x by: 1. - WL: 1.54184 - Rhombo.H.axes - a 4.98900 - b 4.98900 - c 17.06200 - alpha 90.000 - beta 90.000 - gamma 120.000 - Primitive - R-3c (167) - 6 - 367. 00-

031-0966 (*) - Orthoclase - KAlSi3O8 - Y: 84.22 % - d x by: 1. - WL: 1.54184 - Monoclinic - a 8.55600 - b 12.98000 - c 7.20500 - alpha 90.000 - beta 116.010 - gamma 90.000 - Base-centered - C2/m (12) - 4 - 71

Lin

(C

ou

nts

)

d=

2.7

22

38

d=

2.6

52

02

d=

2.5

96

47

d=

2.5

63

78

d=

2.4

43

34

d=

2.4

21

02

d=

2.3

58

38

d=

2.2

80

98

d=

2.1

63

15

d=

2.0

94

46

d=

1.9

86

43

d=

1.9

13

09

d=

1.8

78

33

d=

1.8

18

35

d=

1.7

82

69

d=

1.7

30

55

d=

1.7

04

15

d=

1.6

86

28

d=

1.6

61

70

d=

1.6

03

65

d=

1.5

42

78

d=

1.5

27

66

d=

1.4

69

18

d=

1.4

53

19

d=

1.4

40

89

d=

1.3

77

36

d=

1.3

17

13

XRD Results of a Measurement on APM01161 foot, Created by Luc Megens (RCE Amsterdam)



APM01161 wing

500

400

300

200

100

0

16 20 30 40 50 60

2-Theta - Scale APM01161 wing - File: APM01161_wing_002.raw - Type: 2Th alone - Start: 15.400 ° - End: 63.200 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-Theta: 15.400 ° - Theta: 19.650 °




Lin

(C

ou

nts

)

XRD Results of a Measurement on APM01161 wing, Created by Luc Megens (RCE Amsterdam)



400

300

200

100

0

16 20 30 40 50 60

2-Theta - Scale APM14207 - File: APM14207_001.raw - Type: 2Th alone - Start: 16.000 ° - End: 61.800 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C (Room) - Time

Started: 0 s - 2-Theta: 16.000 ° - Theta: 19.450 ° - Chi: 4.46 Operations: Background 0.081,0.100 | Import

APM14207_ceramic - File: APM14207_ceramic_001.raw - Type: 2Th alone - Start: 16.000 ° - End: 61.800 ° - Step: 0.100 ° - Step time: 180. s - Temp.: 25 °C

(Room) - Time Started: 0 s - 2-Theta: 16.000 ° - Theta: 1 Operations: Background 0.081,0.100 | Import



00-014-0164 (I) - Kaolinite-1A - Al2Si2O5(OH)4 - Y: 45.10 % - d x by: 1. - WL: 1.54184 - Triclinic - a 5.15500 - b 8.95900 - c 7.40700 - alpha 91.680 - beta 104.900 - gamma 89.940 - Base-centered - C1 (0) - 2 - 330

APM14207

Lin

(C

ou

nts

)

d=

5.4

51

51

d=

4.8

07

76

d=

4.3

76

82

d=

4.1

77

70

d=

3.8

44

93

d=

3.5

76

21

d=

3.3

48

35

d=

3.1

51

64

d=

3.0

33

87

d=

2.8

73

58

d=

2.7

54

88

d=

2.6

44

33

d=

2.5

60

61

d=

2.4

96

57

d=

2.3

84

58

d=

2.3

39

90

d=

2.2

95

05

d=

2.1

90

58

d=

2.1

27

14

d=

1.9

89

85

d=

1.9

41

14

d=

1.8

98

88

d=

1.8

76

76

d=

1.8

38

98

d=

1.8

18

42

d=

1.7

89

87

d=

1.7

10

82

d=

1.6

62

43

d=

1.6

23

14

d=

1.5

87

29

d=

1.5

43

18




Appendix V: SEM-EDX Results of Case Study Group

APM00257



APM00277



APM00394



APM01145



APM01161



APM014207

Surface Coatings on Terracotta Objects from Boeotia and ...

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