Pigment Definition and Chemistry

A pigment is a substance that appears a certain color because it selectively absorbs wavelength of light. While many materials possess this property, pigments with practical applications are stable at normal temperatures and have a high tinting strength so only a small amount is needed to see the color when it’s used on objects or mixed with a carrier. Pigments that either fade or else blacken over time or with extended exposure to light are called fugitive pigments.https://848c6ec7886e1043a806080c2432c722.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

Historic and Prehistoric Pigments

The earliest pigments came from natural sources, such as charcoal and ground minerals. Paleolithic and Neolithic cave paintings indicate carbon black, red ochre (iron oxide, Fe₂O₃), and yellow ochre (hydrated iron oxide, Fe₂O₃·H₂O) were known to prehistoric man. Synthetic pigments came into use as early as B.C.E. 2000. White lead was made by mixing lead and vinegar in the presence of carbon dioxide. Egyptian blue (calcium copper silicate) came from glass colored using malachite or another copper ore. As more and more pigments were developed, it became impossible to keep track of their composition.FEATURED VIDEOhttps://imasdk.googleapis.com/js/core/bridge3.493.0_en.html#goog_17079925230 seconds of 1 minute, 22 secondsVolume 0% How Sunscreen Works

In the 20th century, the International Organization for Standardization (ISO) developed standards for characteristics and testing of pigments. The Colour Index International (CII) is a published standard index that identifies each pigment according to its chemical composition. Over 27,000 pigments are indexed in the CII schema.

Dye and Luminescence

A pigment is a substance that is either dry or else insoluble in its liquid carrier. A pigment in liquid forms a suspension. In contrast, a dye is either a liquid colorant or else dissolves in a liquid to form a solution. Sometimes a soluble dye may be precipitated into a metal salt pigment. A pigment made from a dye in this manner is called a lake pigment (e.g., aluminum lake, indigo lake).https://848c6ec7886e1043a806080c2432c722.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

Both pigments and dyes absorb light to appear a certain color. In contrast, luminescence is a process by which a material emits light. examples of luminescence include phosphorescence, fluorescence, chemiluminescence, and bioluminescence.

Pigment Definition in the Life Sciences

In biology, the term “pigment” is defined somewhat differently, where a pigment refers to any colored molecule found in a cell, regardless of whether or not it is soluble. So, although hemoglobin, chlorophyll, melanin, and bilirubin (as examples) don’t fit the narrow definition of pigment in science, they are biological pigments.

In animal and plant cells, structural color also occurs. An example may be seen in butterfly wings or peacock feathers. Pigments are the same color no matter how they are viewed, while structural color depends on the viewing angle. While pigments are colored by selective absorption, structural color results from selective reflection.