How a Can of Paint Gets Its Color
Definition
Paint is any liquid that produces a solid film when applied to a solid surface in a thin layer. Paint is comprised of three substances: a pigment (or other material), a binder (vehicle) and a carrier (solvent). A pigment adds color. A binder allows the pigment to adhere to a surface being painted and forms the film; it also binds the pigments together and influences most aspects of the paint, such as gloss and durability. A carrier is a liquid that allows the pigment and binder to be applied to a surface but does not become part of the paint after it has dried. Often times, extra additives are added to the paint to change some of its properties for specific purposes, such as flow, appearance, thickness and anti-freeze properties.
Example
There are many kinds of paint using different kinds of pigments, binders and carriers. Common latex paint uses a substance, such as titanium dioxide for white, as the pigment, a synthetic polymer as the binder, and de-ionized water as the carrier. The titanium dioxide and synthetic polymer are forced together through grinding until they are thoroughly combined. This mixture is slowly poured into the de-ionized water. A preservative is added to keep the pH level of the paint above seven. The paint is then filtered into cans.
Color
Paints are usually colored by pigments, which are dry powders of various kinds, but dyes or a combination of both may be used as well. Pigments not only add color, they also add toughness or texture to the paint. Pigments are either natural or synthetic. Natural pigments include substances like clay or other ground up natural materials. Synthetic pigments include man-made substances, such as engineered molecules, synthetic silica or natural materials that have been changed by man-made processes. Some substances that are used to create white pigments include titanium dioxide, zinc oxide, white lead and barium sulphate. Examples of substances used to create colored pigments include iron oxide (yellow, red, or brown), chromium oxide (green) and lead oxide (red). The chromates of lead chromate, zinc chromate, strontium chromate and nickel chromate each produce various shades of yellow and orange. Glow-in-the-dark or luminous pigments are often made of phosphorescent sulphides of barium, strontium and calcium. Note that some substances used for pigments are toxic, like lead, and no longer used in residential painting.
