are printing inks, ink
particle cohesion that resists separation on the rollers of a press. Inks
generally exhibit tack rise (i.e., increased stickiness) during
printing, which can result in splitting or picking (surface removal) of the
paper. Tack rise can be controlled to desired levels by adding
solvents with different boiling characteristics
and of different molecular types. Isoparaffins
and normal paraffins impart very low tack
rise; naphthenics, intermediate tack rise; and
aromatics, high tack rise. Tack can be measured
with an inkometer in terms of the torque developed by a system of
rotating ink-wet rollers.
Also see printing
processes, printing ink solvent.