Comparative Study on Blue Pigment of Chinese Blue and White Porcelain and Islamic

glazed pottery

Rui Wen

Brief background of Chinese Blue and White porcelain

Blue-and-white porcelain is a kind of porcelain with underglaze colors, which was made by painting with pigment of cobalt on the body, covered transparent glaze and fired in high temperature (above 1250 0C) .

Blue-and-white elephant-handle bottle with dragon and cloud design Index ware in 1351, preserved in Percival David Foundation

The scientific research on blue and white porcelain started from Alexander Pope in 1950s.

Hypothesis: the blue and white porcelainOrigined in Yuan Dynasty (1271-1368 A.D)

The earliest research contributed by Young, GarnerBanks and Merrick. 1950s-1960s

The Tang (618-907 A.D) blue and white porcelain were found in last quarter of 20th century

The cargo were found in Tang wreckship

The first sherd of Tang blueAnd white porcelain found in 1975

Blue pigment used on the Islamic glazed potteries during 9th – 15th century

Iran, 9th-10th century Louver museum

Iraq, 9th -10th centuryLouver museum Iznik, Turkey around 1510A.D

V&A Museum

In 14th -15th centuries, blue and white porcelain

was mainly produced for exportation

Preserved in Topkapi museum,Turkey(produced in Jing-de-zhen)

Preserved in Louver Museum, France(produced in Mid-East)

Preserved in Topkapi museum,Turkey (produced in Jing-de-zhen)

The main aims

• To study the chemical composition of the cobalt blue pigment used on the Chinese blue and white porcelain and the Islamic glazed pottery.

• get the whole picture of the interaction of the blue pigment in the two co-existent ceramic systems.

Background of Islamic sherds• 25 samples from Fizwilliam museum, Cambridge

provenance

date Samples No.

Syria 14th century Fiz1, Fiz2, Fiz3, Fiz4, Fiz6,Fiz7, Fiz8,

15th century Fiz11, Fiz19

unknown Fiz30

Egypt Before 13th century Fiz27, Fiz28

After 13th century Fiz18

15th century Fiz15

Iran unknown Fiz16, Fiz17, Fiz24, Fiz25, Fiz26, Fiz29

Unkown Unkown Fiz10, Fiz12, Fiz20, Fiz21, Fiz22

Testing method: XRF

Category of glaze Samples’ No. total

Greenish glaze Fiz1, Fiz3 2

Translucent glaze Fiz7,Fiz8 2

Lead glaze Fiz15, Fiz17, Fiz30 3

Yellowish glaze Fiz22, 1

Transparent alkali glaze Fiz2, Fiz4, Fiz6, Fiz10, Fiz11, Fiz12, Fiz16, Fiz18, Fiz19, Fiz20, Fiz21, Fiz24, Fiz25, Fiz26, Fiz27, Fiz28, Fiz29

17

Several types of glaze

Compare the glaze of Chinese and Islamic

The chemical composition of blue pigment

The pigments show different oxides of copper and zinc

• variation of cobalt ores ?

• strict regulation of selection and pretreatment process in Jing-de-zhen Guan (official) kiln.

• high fire temperature of Chinese kilns.

The blue pigments can be distinguished into 3 groups by their chemical composition

Category Samples Characteristics

Group 1 Fitz2,Fitz3,Fitz8,Fitz15,Fitz18,Fitz30

High Fe, Zn, Co; low Cu, Mn

Group 2 Fitz1, Fitz4,Fitz7, Fitz27, Fitz28,Fitz17, Fitz25, Fitz26, Fitz10, Fitz24

Low Fe, Co, Cu, Mn; some Zn

Group 3 Fitz6, Fitz11, Fitz19, Fitz16, , Fitz29, Fitz12, Fitz20, Fitz21, Fitz22

High Cu, low Fe, Co; Mn and Zn broadly distributed

Compared with blue pigment used on Chinese blue and white porcelain

14th century 15th century

Conclusions

• Compared with Chinese porcelain, the glaze of Islamic wares contain more colorant elements and less K. This is the reason why the Islamic glaze looks more shining.

• The chemical compositions of cobalt blue pigments used on Islamic glazed potteries shows variable results, it suggest that the pigment ores had several provenances.

• Most of Islamic samples show quite high oxide of copper and zinc in blue ornament area. However, the difference attribute to strict selection process and high fire temperature in Chinese kilns rather than variation of pigments provenances

• There is cobalt blue pigment (type Ⅰ) shows quite similar chemical composition with pigment used in Early Ming period in China. The kind of pigment supposed used in Syria only in 14th century but it spread to Egypt and China in 15th century.

Acknowledgements

• We are grateful to Dr. Julia Poole and James Lin from Cambridge Fizwilliam museum for their kindly loan the Islamic samples. Thanks for Prof. Michael Tite and Dr. Chris Doherty’s helpful discussions.

Thank you!谢谢 !

The ancient Chinese literature Tian Gong Kai Wu record the the process of selection for the cobalt pigment: They (cobalt ore) are also divided into best, medium and low grades. When it is used, it is first roasted over a charcoal fire, the best grade comes out a kingfisher blue, the medium grade is slightly blue and the low grade an earthy br

own. (Sung, 1637).

• Tao shuo described another process of selection: (the kind of) Hui blue (when) broken up exhibits cinnabar specks was (regarded as) best blue, those with silver stars were medium blue. For every catty, three taels of refined blue was obtained. After the blue is broken up, the small pieces were put in water and a magnet was used to attract the impurities; and after sedimentation, five to six qian (tenth of a tael) of real (pure) blue was obtain from a catty (of the original mineral).

• Some analytical work reported that the cobalt pigment bear oxide of copper and nickel was used in folk kilns.

• no high zinc pigment used in China even in folk kilns has been reported so far.

High fire temperature might be the reason for oxide of zinc absence

• The fire temperature of porcelain was improved above 1200 ℃ as early as in Tang Dynasty

• Theoretically, the oxide of zinc begin to vaporize around 1000 ℃ although it melt point is 1973 ℃.