HIV & AIDS

Vitamin D status related to immune response to HIV-1

Vitamin D plays an important part in the human immune response and deficiency can leave individuals less able to fight infections like HIV-1. Now an international team of researchers has found that high-dose vitamin D supplementation ...

Other

Laser treatment can make your brown eyes blue

Just like the old Crystal Gayle song, a new laser technology could soon allow you to turn those boring brown eyes of your to a rich and beautiful blue. But you better make sure that blue eyes are what you really want because ...

Neuroscience

Why animals don't have infrared vision

On rare occasion, the light-sensing photoreceptor cells in the eye misfire and signal to the brain as if they have captured photons, when in reality they haven't. For years this phenomenon remained a mystery. Reporting in ...

Ophthalmology

Giant hogweed can cause burns and blindness

(PhysOrg.com) -- The U.S Department of Agriculture is warning residents in a variety of states to be on the lookout for the Heracleum Mantegazzianum, or giant hogweed. This plant in native to Central Asia but has turned up ...

Cardiology

Bilirubin protects against heart disease

(Medical Xpress) -- There's new hope for the fight against cancer and cardiovascular disease, following breakthrough research identifying a pigment in our bile.

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Pigment

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.

Many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures.

For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken.

Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food and other materials. Most pigments used in manufacturing and the visual arts are dry colourants, usually ground into a fine powder. This powder is added to a vehicle (or binder), a relatively neutral or colorless material that suspends the pigment and gives the paint its adhesion.

The worldwide market for inorganic, organic and special pigments had a total volume of around 7.4 million tons in 2006. Asia has the highest rate on a quantity basis followed by Europe and North America. In 2006, a turnover of 17.6 billion US$ (13 billion euro) was reached mostly in Europe, followed by North America and Asia. The global demand on pigments was roughly US$ 20.5 billion in 2009, around 1.5-2% up from the previous year. It is predicted to increase in a stable growth rate in the coming years. The worldwide sales will increase to US$ 24.5 billion in 2015, and reach US$ 27.5 billion in 2018.

A distinction is usually made between a pigment, which is insoluble in the vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). The term biological pigment is used for all colored substances independent of their solubility. A colorant can be both a pigment and a dye depending on the vehicle it is used in. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment.

This text uses material from Wikipedia, licensed under CC BY-SA