NATURAL AND ECO-FRIENDLY PIGMENTS
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.
WHAT IS A MINERAL DYE ?
Minerals are inorganic compounds abundantly given by Mother Earth and are rich sources of metallic ions, mineral salts and metal oxides and sometimes used for extraction of certain pigments to dye a yarn. Earth pigments are known for their light-fastness (how resistant to fading it is when exposed to light) and fast drying.
Minerals are drawn out by mining and exploration techniques and once 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.
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.
MINERALS 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.
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.
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 stonewares and Chinese carved lacquerware .
Cinnabar 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.
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 decoratives has been majorly discontinued and most of the cinnabar items in the markets are non-toxic imitation materials.
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.
BROWN AND ITS SHADES
1. BROWN OCHRE
The brown color covers a wide range of the visible spectrum and is a combination of yellow, orange, or red. Its shades are named as reddish brown, yellowish brown, dark brown, light brown and so on. As a mineral-based alternative, Brown ochre is a major source of obtaining brown pigment.
It is basically a limonitic rock which is a mixture of several minerals predominantly goethite. The pigment is absolutely stable and works best with Acrylics, Lime / Fresco, Ceramic, Oil, Tempera, Watercolor / Gouache, Cement.
Brown ochre is well documented in the ancient cave paintings which are still in excellent condition showing their color stability. It is compatible with all other pigments and is often used in mixture with other pigments.
For textile use the pigment is powdered to fine paste. Brown ochres can also be prepared artificially by a variety of procedures. The two main production methods:
- Precipitation of iron oxides
- Thermal decomposition of iron compounds.
Sienna is a yellowish- brown Earth pigment with oxides of iron and manganese. It was first mined near Tuscany and named as terra rossa (red earth), terra gialla, or terra di Siena.
Sienna is used in two of its popular forms:
- Raw Sienna– The naturally occurred sienna is yellow in color. This pigment is known as terra gialla.
- Burnt Sienna- The raw sienna when exposed to heat it turned out reddish brown and known as burnt sienna producing brown pigment. The pigment is also known as terra rossa. This pigment shows various color range including Burnt sienna pigment (Maerz and Paul), Dark sienna (ISCC-NBS), Sienna (X11 colour).
Along with ochre and umber, it was one of the first pigments to be used by humans, and is found in many cave paintings. Since the Renaissance, it has been one of the brown pigments most widely used by artists. In the 20th century, pigments began to be produced using synthetic iron oxide rather than the natural earth.
Another mineral-alternative for brown dye is Umber. It is a natural brown or reddish-brown mineral which is darker than sienna and ochre. The name comes from terra d’ombra, or earth of Umbria, a mountainous region where the pigment was first extracted.
Likewise Sienna, raw umber is light in color but when exposed to heat, it turns darker and intense and thus called as burnt umber, suitable for both oil and water color paint.
Umber is not a word specific to one precise color, but it is a range of different colors, from medium to dark, from yellowish to reddish to grayish. The color of the natural earth depends upon the amount of iron oxide and manganese in the clay.
Seeking historical accounts, one can find ancient usage of Umber:
- Umber was one of the first pigments used by humans
- It is found along with carbon black, red and yellow ocher in cave paintings from the Neolithic period.
- The golden age of umber was the baroque period, where it often provided the dark shades in the chiaroscuro (light-dark) style of painting.
- It was an important part of the color palette of Caravaggio (1571–1610) and Rembrandt (1606–1669).
In the 20th century, natural umber pigments were gradually replaced by synthetic pigments made with iron oxide and manganese oxide. Natural umber pigments are still being made, with Cyprus as a prominent source.
THE BLACK COLOR
Manganese Black is the pigment obtained from the silver-grey colored chemical element which is often found in minerals along with iron. The pigment shows stability in acids and alkalies and also at high temperatures. It shows excellent lightfastness, and is compatible with all other pigments.
Several colorful oxides of manganese used as pigments are :
- Manganese dioxide – Abundantly found in nature and have been used as pigments since the Stone Age. The cave paintings in Gargas that are 30,000 to 24,000 years old contain black manganese pigments.
- Pyrolusite – Often called as Mineral Brown Black is the most common manganese mineral. The pigment is dark brown or brownish black used as a coloring material in calico printing and dyeing. It imparts violet, amber, and black colors to glass, pottery, and bricks and used in the manufacture of green and violet paints.
- Manganese compounds have been used as pigments and for the coloring of ceramics and glass. The brown color of ceramic is sometimes the result of manganese compounds.
- It was used by Egyptian and Roman glassmakers, either to add to, or remove color from glass.
One of the common rock mineral and an important ore of iron. Magnetite yields excellent black color called as Roman Black Pigment. Black earths of Rome and Venice are mentioned by writers, such as De Mayerne. Roman black earth (Terra nera di Roma) is described by Salter as producing ‘the same effect as charcoal black’.
This natural black oxide is dense, opaque, non greasy, non toxic and imparts heavy permanent color. The pigment has cool neutral tone and can be used with any medium.
India Black pigment is a Natural black Oxide from India which is suitable for all media including Artists Paints, Home Decor Paints, limewash, plaster, mortar and grout and more.
THE ULTIMATE – KHAKI
1. MINERAL KHAKI
Khaki is a color, a light shade of brown with a yellowish tinge. Mineral Khaki Color is produced by chemical reaction of metal salt – Iron and chrome more specifically (Iron buff and Chrome green color). The color ranges from chrome yellow, chrome orange, chrome green to manganese brown, iron buff, khaki and Prussian blue.
Mineral Khaki Dye is :
- Generally used to dye cotton fabrics. It can not be used on silk or wool as it decreases the luster and flexibility of silk and wool.
- It is light fast.
- This color dyed is resistant to alkalis.
- It is used for army or military clothes.
Mineral khaki was abandoned prior to Ist World War due to large production of synthetic sulfur colors producing khaki.
Many mineral yielding whites are used as a pigments for white colors, tinting colors and covering tones in paint as inorganic pigments are comparatively easy to disperse in most paint vehicles than organic pigments. They undergo treatment to improve their dispersibility, lightfastness and weather resistance.
ARAGONITE is a white to pale yellow mineral formed by biological and physical processes like precipitation from marine and freshwater environments, limestone caverns, near hot springs and geysers. Aragonite is often found with gypsum, barite, malachite, calcite, quartz, clays, dolomite and limonite among many other minerals.
Historically, Aragonite was used along with dolomite and chalk for creating backgrounds and motives with other pigments by Romans. The long-lasting fluorescent properties of this pigment adds durability as well as luster and brilliance to color mixtures.
It is non-toxic and has good covering power as a white pigment in aqueous mediums, such as egg tempera, distemper and casein. However, aragonite is not effective in oil mediums, because of its low refractive index. It exhibits excellent fluorescent properties.
2. ZINC SULFIDE
Zinc sulfide is an inorganic compound which mainly occurs as zinc in the mineral ore sphalerite. In its raw form, the mineral is usually black due to the presence of various impurities but the pure pigment is white.
It is non toxic to humans and has good lightfastness but it is highly prone to weathering and therefore inadequate for outdoor paints. Ultraviolet radiation combined with humidity oxidizes zinc sulfide to the colorless zinc sulfate (ZnSO4) in paint.
Its uses as a pigment diminished during the past century due to its optical properties which are inferior to those of titanium dioxide. Zinc sulfide is used in paint that requires pigments with low abrasion qualities. This is perhaps its only advantage in comparison to titanium dioxide.
Iron buff is a fabric dye produced with the metal- IRON. In its simplest form, the clothes are dipped in iron springs, containing iron salts in solution. Dipping clothes in these springs and then exposing them to the air dyed them in iron rust color commonly called as ”iron buff”.
In fact, ancient greys and blacks were almost all dyed with iron together with plant tannins. Examples of this technique can be seen in the textiles of the Swiss Lake Dwellers (approximately 3000 BC). Egyptians also dyed with iron liquor and the sails of many Mediterranean fishing boats were dyed buff until quite recently.
Dyeing with iron produces buffs, dull yellows and oranges that are very fast to light and washing. To avoid shortening the life of the fibers too much, mostly cotton or linen are dyed using light shades. Fiber dyed with iron, has already been mordanted and could be over dyed to unusual shades with weld, madder and other natural dyes.
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