Ink is transferred from a plate or stencil to paper or some other material during the printing process. The ink forms the image on the printed product.
Most printing inks consist of pigments, vehicles, and modifiers. Pigment is the ingredient that provides the color of the ink. Many pigment colors are produced from rocks and clays. Others can be traced to plants, sea life, or even insects. Several pigments may be blended together to obtain a desired color ink.
The vehicle is the fluid that carries the pigment. Oil, lacquer, alcohol, and water are all used as ink vehicles.
Modifiers may be added to ink for certain desired characteristics. For example, driers are added to speed up the drying process. Waxes are used to minimize setoff. Setoff refers to the transfer of ink from a freshly printed sheet to the back of the sheet above.