There are 2 kinds of volatile organic solvents and then there are the non-volatile ones. The volatile kinds are used for flexography, photogravure, and serigraphy. The volatile kinds evaporate right after the print has been made and the ink dries immediately. The non-volatile kinds are used for offset printing as evaporation takes a long time.

This is necessary to prevent them from drying up on the rolls or in case of machine stoppage. It takes a long time for these to permeate the paper and dry.

Additives are added to bring different properties to the colour, e.g. drying quality or viscosity etc.