High quality printing inks, including rotary offset and flexographic inks, require careful quality control already at the production stage. Rheological properties must be checked, as well as optical properties and the behavior of the inks during drying. Rheological properties are best checked with a rotary viscometer, although a capillary viscometer is adequate for more simple control purposes.
The fineness of the particles in a printing ink is important for its rheological as well as coloristic characterization. It is normally monitored by means of a grindometer. Triple filter instruments will usually be sufficient for controlling colour. These can, for example, be used to monitor the development of colour intensity and hiding power.