Man made chemical compounds include cadmiums, chrome yellow or zinc white. The difference is in the medium used to make the pigment bind to the painting surface. For oil paints, the pigment is usually ground in linseed or poppy oil. Linseed oil is extracted from the seeds of the same flax plant that produces linen for canvas. Casein paints use a binder processed from the curd of sour milk and tempera uses an egg binder.
Acrylics are a modern addition and use a synthetic polymer as a binder.
All paintings are produced by using an appropriate binder to adhere the pigment to a surface such as canvas, board or paper. If permanence of the painting is a priority, it is important to consider the longevity of the binders as well as the pigments and especially to avoid experimental techniques. Art supply manufacturers include useful information on pigments and other supplies on their web sites. See the links to recommended sites under Suppliers Discuss art and more on the ArtCafe. Net Artists' Message Board .