Glycerol Ester of Rosin GER-80

GER-80 is the primary binder resin component in conventional mineral oil-based offset litho inks. Esterification of rosin with glycerol improves its compatibility with linseed/soy oil varnishes and reduces acid value from ~170 (raw rosin) to <10 mg KOH/g, preventing water pick-up during ink-water printing interactions on offset presses. GER-80 provides the rheology (tack 12–18 Tackmeter units), high gloss, and fast set by absorption into paper that offset printing requires. Typical formulation includes GER-80 at 35–50% in alkali-refined linseed oil varnish, with calcium stearate, PTFE wax, and cobalt/manganese driers. Emerging challenge: UV-curable offset systems increasingly substitute GER-80 with acrylated resins; however, GER-80 remains dominant in heat-set and sheetfed offset printing, particularly in developing markets.