Print Industry Overview - Inks, Varnishes, Coatings, and Toners 

Inks

Consist of 3 parts: a vehicle, a pigment, and a variety of additives (dryers).
Vehicle is what makes the ink fluid. Its job is to “transport” the pigment on to a substrate.
The vehicle type depends on the printing process and the type of ink drying system used.
Some inks dry by absorption into substrate, some by oxidation, some by evaporation,
some by exposure to various forms of radiation.

Offset inks dry by oxidation: as the oxygen from the air is absorbed by and reacts
with the substances in the ink vehicle, the fluid vehicle is hardened (gets polymerized) into a solid ink film. Offset inks also contain pigments that do not easily react with water and chemicals.

Ink pigments are fine insoluble inorganic particles that are suspended in the vehicle and determine the color of the ink, but also provide opacity, transparency, resistance to heat or moisture.

Pigments can be roughly divided into black, white and colored.

Black pigments include carbon or iron dioxides

White pigments can be opaque (cover the surface) or transparent (allow the light through) pigments. The most widely used white pigments are titanium dioxide and zinc oxide

Color pigments – can be inorganic (chromes, cadmiums, irons) or organic (derived form coal), metallics (using various metal flakes).

Dryers allow the ink to “dry” by oxidation. Linseed oil, castor oil, petroleum drying oils and synthetic resins are the most common ones in use.

Varnishes

Exactly the same as ink, except there is no color pigment involved. Applied to printed sheet for aesthetic purposes (gloss / dull / matte look) and to protect the surface from wear and tear.
Varnish usually gets applied the same way as ink – using a plate and a press unit. It can be applied as “flood” (completely covering the sheet surface) or “spot” (only in certain areas of the sheet).

Coatings

Used in some cases to replace varnishes.
Coating is a fast-drying water-based emulsion that gets applied on top of wet ink - usually to the whole press sheet surface (flood coating), using a special coating unit on press.
This is usually a cheaper option to protect printed pieces, providing gloss or matte surface that deters dirt and fingerprints.

Toners

Fine powders used in electrophotography.
A toner powder is mostly made from finely-ground carbon, polypropylene and various minerals.
Typical toner particle sizes are within 8-10 micron range (1 micron is one millionth of a meter), so the toner usually is contained in a toner cartridge. 

Finer toner particles exist, and they get suspended in mineral oil
(an HP Indigo “ElectroInk” for example):

1980 Festival Plaza Drive, Suite 300, Las Vegas, NV 89135-2930

1-702-745-6967