Printing Inks

Rotogravure is a printing method in which the image to be printed is engraved onto a cylinder, forming depressions. During printing, these depressions, also called cups, are filled with soft, paste-like, low-viscosity inks, which are transferred to the print material by contact pressure. The depressions can be created, for example, by etching, mechanical engraving with a diamond etching needle or laser engraving. 

Due to the high cost of the printing plate, rotogravure is especially cost-effective for bulk printed matter with mass circulation such as sales circulars, magazines, decorative films for the furniture industry and wallpaper.

Sheet-fed

Sheet-fed (also referred to as sheet offset printing) is an offset printing method in which the material being printed is fed sheetwise into the printing machine. Offset printing is an indirect printing method in which paste-like printing ink is transferred to the lipophilic printing area of the printing plate via an additional roller – and not to the parts that have been moistened with water. 

Drying takes place through a combination of the physical drying through penetration, the diffusion of the liquid components from the paper surface into the paper, and the chemical drying through oxidation. In contrast to web offset printing, sheet offset printing is suitable for small to medium print runs of valuable art prints but for advertising material, books, packing materials and labels as well.

Cold-Set

Cold-set inks are paste-like offset printing inks. They are used in web-fed offset printing. Because cold-set inks only dry physically by penetrating into the print substrate (paper), the process does not require an ancillary drying device and avoids emissions. Cold-set inks are used predominantly in newspaper printing.

Heat-set 

Heat-set printing inks are used in web-fed offset printing. They dry through evaporation of their mineral oil content in drying furnaces. This is accomplished with hot air at temperatures from 120 to 150°C. This method is used to print magazines, catalogs, newspaper inserts, etc.

Flexo printing, like letterpress printing, is one of the relief printing processes and is used for printing newspapers, books and packaging, particularly for high-quality food packaging. For flexo printing, the printing plate is flexible (photo polymer or rubber printing plates are used) and the impression cylinder is made of steel. 

Solvent- and water-based inks as well as UV inks are used in the flexographic printing process. In addition to the solvent, they consist of pigments, processing aids such as drying accelerators or retardants, additives and binders, as well as photo initiators in the case of UV inks. The processing aids and additives make it possible to precisely tailor the properties of the ink, such as abrasion resistance, flexibility, glide performance, optical density and color strength.

In screen printing, the printing plate consists of a woven mesh with a print template. The screen printing ink is transferred through the printing plate onto the print substrate. The ink application is five to ten times thicker in screen printing than in other printing processes, which makes it especially suitable for high-quality print advertising, signs, posters and packaging. 

In addition, screen printing inks are characterized by their excellent bonding properties and durability on many different materials, such as papers, plastics, textiles, metals or glass.