Most glassware has some kind of discernible shape, which makes pad printing a natural choice. The more complex the shape, the more suitable pad printing becomes as a decorating process.
With the right tooling, multicolor prints, special-effects inks, and even 360-degree wrap-of-image around the circumference are possible. Automated parts-handling options can further speed production rates.
Two primary ink families
There are two primary inks used in pad-printing glassware: frit inks and acrylic inks.
Acrylic inks
Acrylic inks are mixed with a catalyst hardener as well as with a solvent thinner, which allows the transfer from cliché to pad to part. A post-print bake is usually recommended (3–5 minutes at about 200°F) to improve durability. The bi-component ink mixture typically has a “pot life” of 6–8 hours, after which it hardens. Acrylic inks provide at least 50 wash cycles in a home dishwasher.
Frit inks
Frit inks contain finely ground glass particles (only a few microns), pigment for color, a binder carrier, and a thinner solvent. After printing, the ware is fired in a kiln at approximately 1,100°F for up to 30 minutes. Frit inks are generally considered the most durable of all glassware prints, capable of lasting a lifetime and providing tremendous abrasion resistance.