MINERALS FOR- RED, BLUE, GREEN AND YELLOW COLORS
Proceeding with our Eco-friendly series of Natural Pigments, lets continue exploring more sustainable ways of coloring or dying a fabric. We discussed about PLANT BASED PIGMENTS AND DYES and ANIMAL BASED PIGMENTS AND DYES in our previous two post. Now, in the same category falls the third sustainable alternative for synthetic dyes that is- MINERAL BASED PIGMENTS.
Minerals are inorganic compounds abundantly given to us by Mother Earth. They are rich sources of metallic ions, mineral salts and metal oxides and sometimes used for extraction of certain pigments to dye a yarn. Minerals are drawn out by mining and exploration techniques.
To obtain a mineral dye, the pigments present in a mineral are drawn out. The extracted the pigment is suspended in a medium and the medium bonds with the cloth. These mineral pigments works best with natural fabrics like cotton, linen, hemp, wool, and silk.
Earth pigments are known for their light-fastness (how resistant to fading it is when exposed to light) and fast drying.
MINERALS ARE ANCIENT SOURCES OF DYE
Mineral dyes, also called as EARTH-PIGMENTS are one of the ancient sources of coloring a fabric or a painting. Archaeological records have found usage of these pigments since prehistoric times. To cite some-
- OCHRE- Textiles with a “red-brown warp and an ochre-yellow weft” were discovered in Egyptian pyramids of the Sixth Dynasty (2345–2180 BCE).
- OCHRE- Tammy Hodgskiss, an archaeologist at the University of Witwatersrand in South Africa, has studied sites showing evidence of ochre used spans as old as 60,000 years.
- RED OCHRE- Neolithic settlement shows the earliest evidence of textile dyeing in southern Anatolia, from red dyes, possible red ochre.
- CINNABAR- It was used in ancient sites of royal burial chambers during Maya civilization. In 1976, archaeologist found two female mummies dated A.D. 1399 to 1475 in Cerro Esmeralda in Chile, wraped in cinnabar colored clothes.
- AZURITE- It was expensive yet the major source of blue dye for European paintings. It was used since 4th dynasty of Egypt for icon painting.
- LAPIS LEZULI- Lapis was highly valued by the Indus Valley Civilisation (3300–1900 BCE), and lapis jewelry have been found at various Neolithic sites. It was used in the funeral mask of Tutankhamun (1341–1323 BCE).
- MALACHITE- This historical Malachite pigment is found in Egyptian tomb paintings as early as sixth century B.C.
- ORPIMENT– It has been found in the wall decorations of Tutankhamun’s tomb and ancient Egyptian scrolls, and on the walls of the Taj Mahal.
HOW MINERALS ARE USED FOR DYING?
Mostly natural minerals such as ochre, sienna, natural calcium carbonate, talc, mica, umber, quartz powder, azurite, clay and asbestos, etc. with a small number of synthetic products are used to extract pigment.
After mining, the mineral is ground to a very fine powder (if not already in the form of clay) to obtain a pigment, washed to remove water-soluble components, dried, and ground again to powder.
For some pigments, notably sienna and umber, the color depends upon the heat provided. The process is called as calcination wherein the mineral is exposed to higher temperatures to produce darker color pigment.
Lets find out some minerals involved in the creation of beautiful colors:
RED AND ITS SHADES
1. RED OCHRE –
This naturally occurring Clay with rich content of iron oxide yields beautiful range of red and browns. It varies in color from yellow to deep orange. Ochre specifically rich in hematite, turn red and known as “red ochre” with chemical composition Fe2O3.
Ochre is actually an ancient pigment found in various prehistoric textile sites during archaeological excavations.
About 200,000 years age, ancient African women used Red ochre as a coloring agent to achieve a reddish skin tone. The ochre mixture is also applied to their hair after braiding.
Ancient Paintings of animals, engravings on rocks, religious symbols using ochre pigments have been found in various civilizations as old as 75,000 years. Ancient Egyptian women used Red ochre as a cosmetic product typically, lip gloss.
Cinnabar is an ore of mercury with bright scarlet to brick red color. It is a heavy reddish mineral, with a metallic adamantine luster. Cinnabar has been used by ancient people for its red pigment called as vermilion since the times of Mesoamerican civilization.
It also shares history with China where it was used for coloring stoneware’s and Chinese carved lacquerware .
However, it has been scientifically proven that due to its high mercury content, Cinnabar is toxic for human use. Today, Cinnabar usage as a pigment, jewelry and decorative has been majorly discontinued and most of the cinnabar items in the markets are non-toxic imitation materials.
3. LEAD OXIDE OR RED LEAD
Lead oxide or red lead is the inorganic compound with bright red or orange color. The pigment was used in Europe and Rome since medieval periods for the production of manuscripts, and gave its name to the minium or miniature, a style of picture painted with the color.
Due to its toxicity, it has limited application for human use. It is used as a pigment for primer paints for iron objects. Lead is now mostly used in electro-chemical industries.
BLUE AND ITS SHADES
AZURITE, is an ore of copper known for its characteristic deep blue to violet color. Abundantly found in Sinai and the Eastern Desert of Egypt, the blue color of Azurite is known as azure, a word derived via Arabic from the Persian lazhward (لاژورد),referring to a area known for its deposits of , lapis lazuli (“stone of azure”) another deep-blue stone.
Azurite is used as a pigment when ground, as a gemstone and for mineral prospecting. It yields wide hues and tones of blues with different mediums:
- With oil– Slightly Green
- With egg yolk– Greenish grey
During medieval era, Azurite was expensive yet the major source of blue dye for European paintings. It was used since 4th dynasty of Egypt for icon painting (egg tempera), oil painting and watercolor painting without additional grinding.
Azurite pigments were later replaced by man-made pigments such as “Prussian blue” and “blue verditer” during the start of 18th century.
2. LAPIS LAZULI
It is a metamorphic deep-blue colored rock considered as semi-precious stone. The intense blue color is due to the presence of the trisulfur radical anion in the crystal.
Lapis lazuli was mined and exported by Afghanistan since the Neolithic age. Afghanistan traded lapis with ancient Egyptian and Mesopotamian civilizations, as well as the later Greeks and Romans. In Medieval times, lapis lazuli was used in powdered form by Europeans and turned into ultramarine, the finest and most expensive of all blue pigments.
GREEN AND ITS SHADES
Malachite is a “mallow-green” copper rich mineral extracted as a ornamental stone as well as for its pigment. It is an oldest natural green pigment known later replaced by its synthetic form, verditer, among other synthetic greens. Till 1800 Malachite was used as a mineral pigment in green paints with properties like light-fastness, sensitivity to acids, moderately permanent dye and vivid color shades.
This historical pigment is found in Egyptian tomb paintings as early as sixth century B.C. It was more commonly found in egg tempera paintings and often associated with the mineral azurite.
Malachite green :
Malachite green is an organic dye which derive its name from mineral malachite due to similarity of color. This traditional dyestuff is used for silk, leather and paper. Malachite green was first prepared by Hermann Fischer in 1877 by condensing benzaldehyde and dimethylaniline in the molecular ratio 1:2 in the presence of sulfuric acid.
2. GREEN EARTH
GLAUCONITE and CELADONITE are two minerals of mica group which together constitute a natural Earth pigment- Green Earth.
The name Glauconite is derived from the Greek glaucos meaning ‘blue’, referring to the common blue-green color of the mineral. Its color varies from olive green, black green to bluish green, and yellowish on exposed surfaces due to oxidation.
Celadonite, on the other hand, is another mineral of mica family which derive its name from the French celadon, for sea-green. It is soluble in acids and alkalis and turns brown on heating (burnt green earth). The pigment is not changed by light and is compatible with all other pigments.
Both Glauconite and Celadonite , together make the natural pigment, green earth.
YELLOW AND ITS SHADES
1. YELLOW OCHRE
Yellow ochre is a beautiful golden, translucent Earth pigment with other names like yellow Earth or gold ochre. The purest ochers on Earth are excavated from France and Cyprus. The yellow color of this ochre is due to the presence of limonite which is a mixture of several iron-containing minerals.
Darker to lighter Shades of yellow can be obtained by heating the pigment. Under moderate heat, yellowish-red colors are produced; however, the stronger the heat, the more rich and saturated the color. It is a non-toxic, stable, light-fast pigment and can be safely mixed with other pigments.
In historical records, yellow ochre is:
- Used in tempera and oil paintings throughout history.
- Often used in wall paintings in Ancient Roman villas and towns. Yellow ochre represented gold and skin tones in Roman paintings. It is found frequently in the murals of Pompeii.
- The Egyptians used yellow ochre extensively in tomb painting, where men were always shown with brown faces, women with yellow ochre or gold faces.
- The Beothuk may have also used yellow ochre to color their hair.
- The ancient cave paintings with yellow ochre are still in excellent condition after many thousands of years.
Orpiment is a natural orange-yellow arsenic sulfide mineral found in volcanic fumaroles, hydrothermal veins and hot springs. It derive its name from the Latin auripigmentum meaning golden pigment because of its deep-yellow color.
It is toxic, but still used in ancient past since 3100 BCE due to its attractive golden color. It also has been found in the wall decorations of Tutankhamun’s tomb and ancient Egyptian scrolls, and on the walls of the Taj Mahal. It was one of the few clear, bright-yellow pigments available to artists until the 19th century.
However, its extreme toxicity and incompatibility with other common pigments, such as verdigris and azurite, made Orpiment a less popular pigment and its use ended with the emergence of organic dye-based colors during the 19th century.
There are other minerals which are processed to impart grey, black and white tones of colors. We will discuss them in other post.
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