Pigments, dyes, fillers and catalysts (PDFC) are a very diverse range of substances with a vast range of applications. Many are solid inorganic substances that have similar properties, often involving powders, and are therefore grouped to handle common issues.
Pigments have always been considered as valuable by the ancient cultures; the royal blue of the lapis lazuli, the royal purple from the secretions of various seas and the numerous types of ochre pigments.
Pigments are used for colouring paint, ink, plastic, fabric, cosmetics, food, and other materials. Most pigments used in manufacturing and the visual arts are dry colorants, usually ground into a fine powder. This powder is added to a binder (or vehicle), a relatively neutral or colourless material that suspends the pigment and gives the paint its adhesion. A distinction is usually made between a pigment, which is insoluble in its vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution).