heatset

Heatset refers to a drying method used in web offset printing in which the ink is dried by heat as the printed web passes through dedicated drying sections. It contrasts with coldset printing, where inks dry primarily by absorption into the substrate and evaporation with little or no heat, and with semi-heatset configurations used on some substrates.

In heatset printing, inks are typically oil- or resin-based and contain volatile components that are rapidly evaporated by hot air or radiant energy. After application, the inked web passes through heated dryers—often hot-air chambers and infrared sections—and may traverse chill rollers to control temperature before winding or moving to the next processing stage. The result is faster production speeds and higher color density, with reduced ink offset between sheets and improved adhesion to coated papers and some uncoated stocks.

Applications include magazines, catalogs, advertising inserts, and other high-volume commercial print jobs where high image quality and fast turnaround are required. The approach supports high-density solids, fine screening, and sharp text at production speeds that coldset cannot typically achieve on similar substrates.

Limitations include higher equipment and operating costs due to the drying system and energy use, as well as the need for solvent management and ventilation when solvent-based inks are used. Regulatory considerations related to VOC emissions may apply. Advances continue in ink formulation and drying technology to improve efficiency, reduce environmental impact, and broaden substrate compatibility.