Pigments generally are insoluble and are applied not as solutions but as finely ground solid particles mixed with a liquid. In general, the same pigments are employed in oil- and water-based paints, printing inks, and plastics. Pigments may be organic (i.e., contain carbon) or inorganic.
The majority of inorganic pigments are brighter and last longer than organic ones. Inorganic pigments include white opaque pigments used to provide opacity and to lighten other colours. The most important member of the class is titanium dioxide.