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Physiology or Psychology of Colors
Transcript of Physiology or Psychology of Colors
Physiology or Psychology of Colors
Color has an astounding effect on perceptions & feelings.
Different colors evoke different memories & ideas.
For instance in China the color red
tends to make people feel calm, while
in America red tends to make people
more aggressive. � effect of color on
a persons mind is perceptual, rather
then being physiological & inherent
���� an effect of social training of the
individual
Therefore people dislike unusual
combinations of food, furniture bed
sheets etc with unusual colors.
Examples: green or yellow caviar
or sauerkraut, green or black bed
sheets, green or spotted TV sets ….
The earth tones (browns, oranges, & yellow) Browns cause feeling of
ease & belongingness & safety, and family.
Here is what Joe the Plumber thinks:
Blue & green evoke serenity and peace associated with nature & ocean
White is uninspiring; it is the generic look for many offices. Good color
for warm climates as it reflects light creating cool and breezy feeling
Black is an attention grabber; it also makes rooms look
small and seem restrictive. It darkens a person’s mood
Orange makes people happy, stimulates appetite
Yellow creates a short-term positive effect on the
psychology of people.Long exposure can lead to irritation.
Pink is an extreme calming color: one finds it
impossible to act aggressively against pink creatures �
Red is an exciting color. Red makes Americans aggressive. It speeds up
their metabolism and gives them energy & inspiration
Green is the color of growth, freshness, & welcome
The Subconscious Importance of food Color
Aim is to simulate the color expected by consumer to be
natural such as adding red coloring to glacé cherries
(would otherwise be beige), but also just for effect, like
green ketchup Heinz launched in 2000.
Few people know that seemingly "natural" foods such as
orange & salmon are also dyed to mask natural variations
Why adding dyes to products:
People associate certain colors with certain flavors,
the color of food can influence the perceived flavor
Some of the primary reasons include:
Offsetting color loss due to light, air,
temperature, moisture, storage conditions
Masking natural variations in color.
Enhancing naturally occurring colors.
Providing identity to foods
Protecting flavors from damage by light
Maraschino cherries are
preserved in brine + sulfur dioxide
or alcohol, then soaked in a
suspension of red food dye FD&C
Red 40 +sugar syrup, artificial
almond flavor, while cherries dyed
green by combination of FD&C
Blue 1 & FD&C Yellow 5 are
sometimes peppermint-flavored.
Subconscious effects of Color on Taste
If cherries, & beetroot
were snowy white
instead of red, would
they taste the same to us
Would chocolate taste
different if it were
bright blue?
Do garden peas and
spinach have an
intrinsically green taste?
There is no actual correlation between color and taste, but there is a
perceived one., if something was dirt brown and not chocolate, we'd be
very put off, even if it tasted the same as our favorite fruitcake.
Food presented in an unorthodox manner is dismissed as disgusting
Green caviar, chocolate, meat, blue fish meat
An antigen is a substance that is a close enough fit to bind to the specific
site of an antibody.
Food Colors
An allergen is a substance that binds to specific site of an IgE antibody
Color Additives Permitted For Direct Addition To Human Food (USA)
Certifiable Colors Colors Exempt from Certification
FD&C Blue No.1 (Dye and Lake), Annatto extract, B-Apo-8'-carotenal*,
FD&C Blue No.2 (Dye and Lake), Beta-carotene, Beet powder, FD&C
Green No.3 (Dye and Lake), Canthaxanthin, Caramel color,
FD&C Red No.3 (Dye), Carrot oil,
FD&C Red No.40 (Dye and Lake), Cochineal extract (carmine);
FD&C Yellow No.5 (Dye and Lake), Cottonseed flour, toasted FD&C
Yellow No.6 (Dye and Lake), Ferrous gluconate *, Orange B*,
Citrus Red No.2* Grape color extract*, Grape skin extract*
Paprika, Paprika oleoresin
* restricted to specific juices Riboflavin, Saffron, Titanium dioxide*,
Turmeric, Turmeric oleoresin,
Fruit juice, Vegetable juice
In US, FD&C indicates that FDA has approved colorant for use in
Foods, Drugs and Cosmetics: numbers are given to synthetic food dyes.
In EU, E numbers for all approved additives, both synthetic & natural,
Natural colors are not required to be tested by a number of regulatory
bodies throughout the world, including the United States FDA.
Common Uses of Artificial Food Colors
Common Food Uses
FD&C Blue No.1 dairy products powders, jellies, confections
Brilliant Blue FCF Bright blue Beverages condiments, icings, syrups,
FD&C Blue No.2 Baked goods, cereals, snack foods, ice cream,
IndigotineRoyal Blue confections, cherries
FD&C Green No.3 Beverages, puddings, ice cream, sherbert
Fast Green FCF Sea Green, cherries, confections, baked goods, dairy FD&C
Red No.40 Gelatins, puddings, dairy products,
Allura Red AC Orange-red confections, beverages, condiments
FD&C Red No.3 red Cherries in fruit cocktail and in canned
ErythrosineCherry fruits for salads, confections, baked goods,
dairy products,
FD&C Yellow No.5 Custards, beverages, ice cream
TartrazineLemon Yellow, confections, preserves, cereals
FD&C Yellow No.6 Cereals, baked goods, snack foods, ice cream
Sunset YellowOrange, beverages, dessert powders, confections
Natural food dyesAnnatto E160 cis-bixin + norbixin from red-colored resin coating of the
seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish
Anthocyanins E 163 common red + blue pigment of most flowers, fruits
Betalains E162 red pigment of beetroots, Swiss Chard, pokeweed,
Curcumin E100, yellow pigment of turmeric spice, not water-soluble
Cochineal E120: insect-cactus-derived red pigment from crushing
female Dactilopius coccus insects, expensive rel. to carminic acid
Orcinol E121, red pigment derived from lichen Rocella tinctoria
converted to orcein (red-brown microscopic dye), with ammonia to
orchil – a blue pigment
Carbon black E153 charcoal from plants & animals in liquorice, jam
Capsanthin E160 capsorubin extract from paprika pepper, in eggs, meat
Caramel E150 brown ammonia-treated sucrose in beer, wine, bread, …
Natural food dyesCarotene cis-bixin + norbixin from red-colored resin coating of the
seeds of tropical bush Bixa orellana) in cheese, oil, butter, smoked fish
Lycopene E160 common red + blue pigment of most flowers, fruits
Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg
& are more stable & water soluble olive-green dye
Lutein red pigment derived from lichen Rocella tinctoria converted to
orcein (red-brown microscopic dye), with ammonia to orchil – a blue
pigment
Chlorophyllin E140 in sweets, soups Copper chlorophyllins repl Mg
& are more stable & water soluble olive-green dye
Rhodoxanthin charcoal from plants & animals in liquorice, jam etc
Caramel Caramel is made by heating sugar slowly to around 170 °C (338 °F).
As the sugar approaches this temperature, it melts proceeding to
isomerization & polymerization of the sugars into various high-weight
compounds providing the dark color. Fragmentation reactions result in
volatile low- molecular-weight compounds that create flavor together
with difructose-anhydride. Candies & desserts made with caramel.
Caramel apples or taffy apples
are created by dipping or rolling
apples-on-a-stick in hot caramel,
then rolling them in nuts or other
stuff, and allowing them to cool.
4 cups sugar in sauce pan, add 2 cups water, heat to 170 C water will evaporate, solutin
goes through var stages, watch for brown color, stop because it blackens quickly
Analysis with Natural Pigments
Litmus is water-soluble mixture of different dyes extracted
from lichens, especially Roccella tinctoria, Orchella weeed
or orchil. The mixture has CAS number 1393-92-6. If
absorbed onto filter paper. it becomes a pH indicator.
Cudbearobtained from the lichens
Ochrolechia. Lichen dyes were dissolved in
human urine � gyrophoric acid –yellow dye
Wolfbane lichen (Letharia vulpina), a
fruticose lichen that grows on the bark of pines,
contains a mildly toxic yellow dye called
vulpinic acid.
A brownish dye from the foliose lichen
Parmelia omphalodes is used on hand-woven
Harris tweeds from Scotland..
Dyeing with Natural Pigments
Nothing is more colorful than flowers, insects and birds. However,
early humans must have been frustrated to realize that the dyes
from insects and birds cannot be extracted.
Exceptions confirm the rule:
cochineal, a red dye, + Lac, a scarlet dye is made from ground up
insects.: carmine comes from cochineal (natural red 4) lac (natural red
25) and hematein which comes from the logwood tree (natural black 1).
Tyrian purple was an expensive dye in antiquity extracted from the
aquatic mollusk Murex brandaris. imperial purple is a purple-red dye
which was first produced by the ancient Phoenicians in the city of Tyre.
Plant Colors & Humans
The painters of the walls of Lascaux & Altamira
used mineral pigments, the Celts of Britannia did
not blue themselves with woad (as ascerted by
Caesar) but with Copper minerals
Experimenting with plants, that the beautiful colors of
flowers are ephemeral. They do not adhere to body or
cloth, wash out easily & fade in the sun. (exception is
anatto serving the Secoya Indians well). Early humans
used minerals for cave paintings & body ornaments.
To make plant dyes last meant mastering the chemistry of
dye binding & fixation to the fabrics such as wool &
cotton. Mordants like fermented urine, vegetarian ashes,
and minerals like aluminum & potassium sulfate ( =
alum) were used.
Egyptians stained their flax fibers blue with extract from
Acacia, red with Safflower, & yellow with madder.
Dyeing with Plant Dyes
Many dye plants need no mordants since they
contain lots of tannins on their own.
Lichens, Black Walnut fruit hulls, Oak
acorns, alder catkins, sumac berries etc.
No mordants needed
Dyes like tumeric, beets , blueberries, apple
peels, cherries etc. need mordants to become
permanent 7 stand up to fade & wash testing.
Mordants are substances that bind or fix the
dye permanently to the fibers.
Most common mordants are (1) ALUM= Al, K, NH3 sulfates normally used 1,5 g / l
& CREAM of TARTAR (= tartaric acid, i.e.
wine acid, normally used at 2.5 g / l
Plant Colors & Humans
Indigo. Leaves were harvested & mashed
in water. Beating the slurry aerated the mix
& precipitated the dye, then dried & shiped
Classical Europe imported most plant stains from Asia.
Wood dyes. The dark heartwood of the
Indian Sander or Sandalwood tree Pterocarpus
santalinus (Fabaceae) produced the brilliant water-
soluble red of Indian textiles. An alternative source
were the pods of the Sapper tree, also an Indian
legume. Much later in History replaced by
American trees like Brazilwood & Quebracho.
Cochineal. It is a red dye obtained from scale
insects living Kermes oaks e.g in Armenia.
Insects were harvested in the fall, pressed into a
material called kermes & shipped to the west.
Flower Pigments
Dyers’ Chamomile (Anthemis tinctoria)
Beautiful daisy flowers which yield a strong
yellow dye, the flower heads are harvested and
used when freshly picked or dried for winter
storage.
Safflower flower heads are dried & used for
colouring foods & clothing, and making red
(carthamin) & yellow dyes (carhamidin – a
flavonoid),
The roots of the madder plant Rubia tinctorum
supply the coloring substances that are converted
to madder lakes, the principle coloring substance
which is alizarin. The shades of colors vary from
scarlet (stannous madder lakes), carmine red (to
red with a bluish tint (alizarin lakes).
Flower Pigments
Tanacetum vulgare, Tansy, Roundish, button-like, yellow flower
heads in terminal clusters from mid-to-late summer. Traditional
dyers use both tansy leaves & flower buttons to produce a golden-
yellow color (flavonoids). For 100 grams wool you need 300
grams tansy. The plant can also be dried. Before dyeing simmer
wool for 1 h at 90 C in alum solution. 20 g alum for 100 g yarn.
Other common names include Weld (Reseda
luteola), Dyer's Rocket, dyer’s broom, is a
European plant with long spikes of small, yellowish-
green flowers cultivated as a source of yellow dye
Calendula officinalis, Pot Marigold, Asteraceae. native to southern
Europe. The petals and pollen of Calendula officinalis contain the
carotenoids flavoxanthin and auroxanthin as antioxidants, & source
of their yellow-orange coloration. The carotenes promote the
renewal of skin tissue + antibacterial properties prevent infections.
As a rinse for the hair, pot marigold gives a golden tinge to fair
hair: Viking women used it to dye their hair & textiles yellow.
Flowers to Color � Marigold petals do not fade
Marigold (Calendula officinalis) in Asteraceae,
native to Iran. not to be confused with other
marigolds, such as Tagetes, corn or marsh marigolds.
Petals used to add color to salads (carotenes, 80 %
lutein + flavins), extract is common food additive to
produce darker egg yolks. Aroma not sweet,
resembles hops in beer. The oil from its seed contains
calendic acid.
Perfume oil of patchouli
Once used as blond hair dye, still wholesome
coloring agent in for cheese, soups & salads +
textiles: for 110 g cotton/wool: Needs previous
1 h cooking in mordant: 30 g alum + 10 g
tartaric acid in 300 ml water. Transfer to
simmering solution of 250 g flowering heads,
cover with water & boil until right color is
achieved.
Used by Gipsy women to keep
their hair black.
Herb yields dark pigment
Gypsies were reputed to stain their
skin with the juice of the plant,
althgough Howard (1987) states
that they used it to dye their linen
Gipsywort Lycopus europaeus
Extract red- to-
dark brown
pigment with
hot water.
Nature of
pigment
unknown!
plant melanin??
Henna (Lawsonia inermis, is a flowering plant
form North Africa. it does not thrive where
minimum temperatures are below 11 °C. used
since antiquity to dye skin, hair, fingernails, leather
and wool. Lawson is a Quinone that stains proteins.
Henna Lycopus europaeus
For skin dyeing, a paste of ground henna
(either prepared from a dried powder or
from fresh ground leaves with lemon juice
or vinegar) is placed in contact with the
skin from a few hours to overnight. Henna
stains can last a few days to a month
depending on the quality of the paste,
individual skin type, and how long the
paste is allowed to stay on the skin. Henna
also acts as an anti-fungal and a preservative , it
is a UV protectant.
lawsone
Lawsone (2-hydroxy-1,4-
naphthoquinone), also known as
hennotannic acid is a water-soluble
red-orange dye
From the leaves of the henna plant
(Lawsonia inermis) as well as
jewelweed (Impatiens balsamina).
Henna Lycopus europaeus or jewelweed (Impatiens balsamina).
lawsone
jewelweed
Slightly acidic henna extracts contain
lawsone, which reacts chemically with
the protein keratin in skin and hair,
Lawsone strongly absorbs UV light, and
aqueous extracts can be effective sunless
tanning sunscreens. Chemically, lawsone
is similar to juglone, which is found in
walnuts..Walnut Juglans
Indigo as in blue jeans (Strauss 1873)
Is challenging dye to use because it is
not soluble in water; to be dissolved,
water must be free of oxygen.
In temperate climates
indigo is obtained from
woad (Isatis tinctoria) and dyer's
knotweed (Polygonum tinctorum).
BASF developed a commercially
feasible manufacturing process in
1897, by 1913 natural indigo had
been almost entirely replaced
How to stain clothing with Indigo Indigofera tinctoria)
India was supplier to Europe as
early as Roman era. Association of
India with indigo is reflected in
Latin word indicum, for the dye
Extraction of indigotin from leaves:
extraction in O2-free alkali turns
water blue in 24 h. Aeration
(paddling) precipitates indigotin.
Blue sludge is dried and sold.
Requires no mordant, but alkaline
(add 1 TBS alkali NaOH to 1 l water
pH 10-11 + 1 oz of indigo powder) &
O2-free bath (add 1 TBS thiourea
dioxide or Na hydrosulfite). Wait 15
min to reduce & mix � solution
turns from transparent green-yellow
to blue showing oxidized form. Test
by dripping some solution on paper.
Cotton requires pH 11.
Woad biennial in family Brassicaceae
Woad also name of the blue dye. The
blue pigment indican is the same as in
indigo, it is insoluble in water, alcohol,
but soluble in chloroform, H2 SO4
woad might prevent cancer, having
more than 20 times more glucobrassicin
than broccoli. Young leaves when
damaged can produce even more
glucobrassicin, up to 65 times as much
leaves crushed with wooden rollers,kneaded into 3-inch-diameter balls.
This gave the workers black hands. balls were dried and ground into
powder piled into deep layers. layers were watered to ferment
(breakdown of indican, a glycoside - to dyestuff indigotine) producing
horribly foul odors from sulfur-containing glucobrassicins . After two
weeks of fermentation, the leaves dried; powder contained indigotine
Woad (Isatis tinctoria )
Red Indian Dyes
Navahos made the famous Navaho rugs for US tourists from wool
(sheep introduced by Spain), very selective colors have symbolic
meaning: Red = sun and life, Indians themselves “the people”,
Yellow, orange = sunset or the ending, White = dawn or the
beginning, Black = rain and joy (Seattle?)
Alnus sp. Alder, bark stained deerskin red-brown
Coreopsis. Blossoms dye wool dark red
Opuntia prickly pear: fruits boiled with salt spruce bark
Rhus sumac berries used to dye baskets & body
Sanguinaria Bloodroot pounded rhizomes gave face paint
Rust or Iron ores, red to brown for totem poles and body
Animal blood mixed with fat used to color totem poles
Indigofera leptosepala Native indigo ferment. in urine
Chrysothamnus sp. Rabbit brush bark boiled to produce
green color, the flowers boiled for 6 hours for deep yellow
Xanthorhiza yellowroot for baskets
Hydrastis canadensis goldenseal roots for baskets
Xanthorhiza yellow root ���� berberine
The Yellowroot (Xanthorhiza simplicissima, syn. X.
apiifolia) is one of the few plants in the family
Ranunculaceae with a woody stem (the other notable
example being Clematis), native to the eastern
United States. It was used to produce a yellow dye
by Native Americans. The species name refers to the
simple (not branched) root.
While yellowroot is toxic in large doses, it has
been used as a substitute for Hydrastis
canadensis. Native Americans also used it to treat
various skin ailments. According to Foster &
Duke (1998), the plant contains berberine which
is anti-inflammatory and can produce a transient
drop in blood pressure.
Xanthorhiza yellowroot and also Hydrastis
canadensis goldenseal roots were used to dye
baskets
Alizarin is an anthraquinone
originally derived from roots of
the madder plant. Tut’s cloth had
it. 1869 first pigment to be
duplicated synthetically. Related
dyes: Alizarine Cyanine Green G
Alizarine Brilliant Blue R
Madder is the common name of
Rubia, a genus of 60 species of
perennial climbing native to Old
+ New world: Common Madder
(Rubia tinctorum), Wild Madder
(Rubia peregrina), and Indian
Madder (Rubia cordifolia).
Madder (Rubia tinctorum) � alizarin red
From the Arabic Alkanna ( a
term for henna).
The root has a red unidentified
pigment. The leaves have highly
poisonous alkaloids
Alkanet - Pentaglossum sempervirens
Anthraquinone resorcinol-type pigment is easily extracted from Alkanet
root by oil & ethanol. It imparts a ruby red color to natural fibers,
wool, wood, stone, lip balm, lipstick, ointments, salve, soap, lotion, and
to tint oils, vinegar, tinctures, varnishes, or wine. In the past, it was used
to improve the appearance of low quality wines and ports, and to give an
aged appearance to wine corks. In soap, it will yield shades of pink,
blue, and purple, depending upon the amount used, types of oil used,
and the alkalinity of the soap.
Saffron, has for decades been the
world's most expensive
spice,derived from the 3 dried
stigmas of the flower of the
saffron crocus (Crocus sativus).
Stigmas are dried & used in
cooking as a seasoning and
coloring agent.
Saffron - Crocus sativus
Saffron has a bitter taste & hay-
like fragrance; It also contains a
carotenoid dye, crocin, that gives
food a rich golden-yellow hue.
Saffron also has medicinal
applications.
Crocin – a carotenoidal glycoside
Woad biennial in family Brassicaceae
Woad also name of the blue dye. The
blue pigment indican is the same as in
indigo, it is insoluble in water, alcohol,
but soluble in chloroform, H2 SO4
woad might prevent cancer, having
more than 20 times more glucobrassicin
than broccoli. Young leaves when
damaged can produce even more
glucobrassicin, up to 65 times as much
leaves crushed with wooden rollers,kneaded into 3-inch-diameter balls.
This gave the workers black hands. balls were dried and ground into
powder piled into deep layers. layers were watered to ferment
(breakdown of indican, a glycoside - to dyestuff indigotine) producing
horribly foul odors from sulfur-containing glucobrassicins . After two
weeks of fermentation, the leaves dried; powder contained indigotine
Woad (Isatis tinctoria )
Genista tinctoria, with common
names: Dyer's Broom, Dyer’s
Greenweed. I t was from this plant
that the isoflavone genistin and its
aglucone, genistein,was first
isolated in 1899; and hence the
name of the chemical compound.
The medicinal parts are the
flowering twigs. The tincture or
extract can be used externally for
herpes or tetters.
Dyer’s Rocket Genista tinctoria
Pigment is a Flavonoid: 2 % of the dry
weight Plant material extracted with
hot water, add wool or silk to to extract
and simmer at max. 80°C
Other species with flavonoids
is Weld (Reseda luteola), The
yellow dye was obtained from
the roots of R. luteola by the
first millennium or 900 BC
Mignonette (Reseda) is a genus of
fragrant herbaceous plants native
to the Mediterranean region The
species include annuals, biennials
and perennials, and grow to 40-
130 cm tall. Flowers are produced
in a slender spike, each flower
small (4-6 mm diameter), white,
yellow, orange, or green, with four
to six petals. The volatile oil is
used in perfumery.
Weld: Reseda luteola + R. odorata
Pigment is a Flavonoid: 2 % of the dry
weight
Plant material extracted with hot water,
add wool or silk to to extract and
simmer at max. 80°C
Other species is Weld (R.
luteola), Dyer's Rocket
The yellow dye was obtained
from the roots of R. luteola by
the first millennium or 900 BC
Lincoln green is the color of dyed
woolen cloth associated with Robin
Hood and his merry men in Sherwood
Forest, Nottinghamshire The dyers of
Lincoln, a cloth town in the high
Middle Ages, produced the cloth by
dyeing it with woad (Isatis tinctoria)to
give it a strong blue, then overdyeing it
yellow with weld (Reseda luteola) or
dyers' broom, Genista tinctoria.
Robin Hood – the green of forest bandits
Pigment is a Flavonoid: 2 % of the dry
weight
Plant material extracted with hot water,
add wool or silk to to extract and
simmer at max. 80°C
Other species is Weld (R.
luteola), Dyer's Rocket
The yellow dye was obtained
from the roots of R. luteola by
the first millennium or 900 BC
Native to SE Europe,
contains 5-10 % tannic acid
(= natural mordant)
�subtle dye from elephant grey
to parchment (beige).
�Chestnut tannin is one of the
pyrogallol class of tannins.
�Since it tends to give a reddish
tone to the leather, it is often
used in combination with
quebracho.
Chestnut - Castanea sativa Horse chestnut Aesculus hippoc.
Aesculus hippocastanum is a large
deciduous tree, commonly known
as Horse-chestnut. Native to small
area in mountains of the Balkans.
Aesculin is fluorescent whitener
saponin aescin, used for health
(varicose veins, edema)
Used are the hulls = exocarp or
outer coverings of the fruit
Walnut hulls are substantive or
direct dyes = no mordant required
contains > 10 % tannic acid and
quinone pigment juglone
� Rich brown color of juglone
do not raise temps above 180 F and
10 % walnut extract
Black Walnut Juglans nigra
Walnut hulls gave the famous
grey color for the cotton uniforms
of the Confederate Army during
Civil War
Cutch tree is native to India is
used for many purposes breath
freshener & diuretic
The wood is chipped and boiled,
the sap dissolves & liquid becomes
syrupy. Liquid is cooled, pressed,
cut into pieces & ground into
powder
When dyeing with cutch extract
the dye becomes not only deeper
but redder the more it is simmered.
Other wood dyes:
Logwood Heamatoxylon, red alder
Alnus rubra, red sandalwood,
fustic Chlorophora etc.
cutch – Acacia catechu – a wood dye
Dye for all fibers :
with alum� yellow-to-red brown
with iron sulfate � black-brown
with soda ash=Na carbonate � red
Carminic acid & Scleranthus perennis
Carminic acid is a red glucosidal
anthraquinone structure that occurs
naturally in some scale insects such as
the Mexican or Polish cochineal.
insects prod. acid as feeding deterrent.
Carminic acid is pigment in carmine.
= C.I. 75470 and C.I. Natural Red 4.
Perennial knawel (Scleranthus
perennis ) is a perennial herb of the
carnation family. It grows on sandy,
dry, acidic soils of Central Europe.
Polish carmine
scales are used to
produce a crimson
dye colloquially
known as Saint
John's blood.
larvae of P.
polonica live on
the roots of various
herbs – esp. knawel
(from Knauelkraut
German)
Logwood tree (Haematoxylum
campechianum grows in Central America &
led to founding of Belize from British
logging camps of 17th century. an important
histological stain. (H. + Eosin = popular for
animal cells
Haematoxylin, hematoxylin, Natural Black 1, or
C.I. 75290 extracted from the wood of the tree.
oxidised it forms haematein = blue-purple color,
used, together with a suitable mordant (Fe(III) or
Al(III) salts), to stain cell nuclei. Structures that stain
with haematoxylin are called basophilic.
Related to Brazilin - red
pigment from brazilwood
Caesalpinia. Natural red 24
= dye for fabric, paints, inks
in acidic sol yellow, alk red
Logwood tree (Haematoxylum campechianum)