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Science Of Pigment

Chemistry for Kids

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INTRO

SCIENCE OF PIGMENT

All paint is made from an essential ingredient known as pigment. These tiny particles are ground coloured material were first extracted from earth or clay. Even though we continue to use age old processes to prepare pigments and convert them into paint, modern pigments are synthesized in laboratories.

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INTRO

SCIENCE OF PIGMENT

The following properties are taken into consideration when talking about the quality of both synthetic and natural pigments:

Lightfastness: the rate at which a pigment fades when exposed to light. Heat stability: how pigments react when exposed to heat. Toxicity: the degree to which it can damage a living or non-living thing. Tinting strenght: how much pigment is required to produce a particular shade. Opacity or transparency: whether one can easily see the under layers of paint once the top layer is dry.

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BLUE

SCIENCE OF PIGMENT

The source of blue pigment used to make

ultramarine

is the semi-precious stone- lapis lazuli. Natural ultramarine is the most difficult to produce because the hard lapis lazuli must be ground into a fine powder in order to make paint. The earliest noted source of the colour were in Afghanistan.

Blue

was used very sparingly in art because of how difficult this colour was to produce. Artists would go as far as to only paint the top layer of blue with ultramarine to cut down costs of painting.

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BLUE

SCIENCE OF PIGMENT

Azurite is a soft, blue mineral of copper

that has many uses including the production of blue pigment. The process to produce the colour azure is similar to making its more expensive cousin. However, since it is a mineral of copper, the pigments turn slightly green when added to oil and green-gray when added to egg yolk (also used as a base in natural paints).

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BLUE

SCIENCE OF PIGMENT

Another shade of blue that has an extensive history is Indigo. The colour Indigo is named after India, the earliest known production center of this pigment. The relatively cheaper means of production than ultramarine made the colour an important trade commodity. It was exported west as far as Greece and Rome in the 7th century BC as a luxury item. Indigo is produced by fermenting the leaves of the Indigofera tinctoria plant and mixing it with dye to form a blue-coloured powder.

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BLUE

SCIENCE OF PIGMENT

Cerulian blue

was discovered in 1805 by a man named Andreas HĂśpfner. It is made from cobalt and is prized because of its pure colour. It is particularly prized in the art world because it is opaque, it does not fade easily, and it does not emit any hues of green (unlike other blue pigments).

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RED

SCIENCE OF PIGMENT

Vermilion is an opaque orange-red pig-

ment that occurs in the mineral cinnabar. It is one of the oldest used colours in the world as cinnabar is a common mineral found around the world. The mineral is ground into a fine powder and heated with mercury and sulfur before it is ready to be mixed with a paint-base. However it is also used without these chemicals like in India where married women use Sindoor, a red streak of vermilion in the parting of their hair.

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RED

SCIENCE OF PIGMENT

Carmine,

also known as crimson lake or cochineal red is a bright red colour derived from the aluminium salt of carminic acid. This might sound complicated but this acid is found naturally in the cochineal insect. The insects are dried and boiled in water to release the pigment. The water is them treated with a chemical to make this liquid into a powdered pigment.

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RED

SCIENCE OF PIGMENT

Madder lake sounds like the name of

a body of water in a fairytale but in fact is the name of a pigment that has been used for centuries. This natural pigment is extracted from the roots of plants of the 'madder' family. The outer brown layer of the root gives a common variety of the dye while the inner yellow layer turns bright red when fermented.

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GREEN

SCIENCE OF PIGMENT

Malachite is used in the production of

green pigment much in the same way as Ultramarine. This copper carbonate mineral occurs naturally in the Ural mountains of Russia, many parts of Africa, France, Italy and the United states.

Paris green is an inorganic compound

of copper. This poisonous substance is named Paris green because it was used to kill the rats in Parisian sewers. The compound can be ground into a fine powder to produce a lighter, vivid green or left a little coarser for a darker shade. It is used even today in paint production despite its high toxicity. Copyright Š 2012 Mocomi & Anibrain Digital Technologies Pvt. Ltd. All Rights Reserved.


GREEN

A

SCIENCE OF PIGMENT

highly

expensive green pigment is Cobalt green, made from the element from which it gets its name. The green extracted from cobalt fades very easily when exposed to light. The combination of high cost and because it fades easily is the cause for its disuse. However scientists found that cobalt has certain magnetic properties that has increased the efficiency of computer storage devices.

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YELLOW

SCIENCE OF PIGMENT

The colour India Yellow used to be produced by collecting cow urine of cattle that had only been fed mango leaves. The urine was collected in pots and heated over a fire. The concentrate was filtered and the remaining sediment was made into balls, then dried and then made into yellow paint in Europe. It was a preferred shade of yellow because of its florescent hue.

Naples yellow,

also known as antimony yellow, is one of the oldest synthetic pigments around. The old masters of Europe used this pigment extensively but is not used anymore because it is very toxic.

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YELLOW

SCIENCE OF PIGMENT

The colour gets its name from the natural deposits of lead antimoniate which was extracted from Mt. Vesuvius just outside of Naples.

Hansa yellow is a synthetic pigment

used in inks, and oil and acrylic paint. It was first made in Germany just before WWI and has replaced its predecessors such as Cadmium yellow, Chrome yellow, orpiment, and gamboge because it is not toxic. For more such fun chemistry articles and videos, visit: mocomi.com/learn/science/chemistry/

Image references:

Indian pigmants source: www.wikipedia.org. This file is licensed under the creative commons attribution 2.0 generic.

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Science of Pigment – Mocomi Kids