Print Process Descriptions: Printing Industry Overview: Lithography

Sheetfed Offset Lithographic Printing

The sheetfed offset process is used mainly for relatively short runs in the production of commercial and packaging products. In sheetfed lithography, the paper or paperboard substrate is normally delivered to the facility in sheets. If rolls are supplied, the paper or paperboard must be sheeted (cut into sheets and trimmed before printing.

Major categories of chemicals used in the sheetfed offset process include film developers and fixers, inks, blanket and roller washes, and fountain solution concentrate. Isopropyl alcohol and glycol based, lower VOC, products are widely used in fountain solutions.
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Sheetfed lithographic inks are paste inks primarily composed of petroleum products, a portion of vegetable oils and pigments, that dry by oxidative polymerization and adsorption into the substrate, rather than evaporation, and therefore do not generate large amounts of VOC emissions. The majority of VOC emissions come from isopropyl alcohol used in the fountain solution and cleanup solvents used to clean ink fountains (trays that hold ink), rollers, blankets and other press components.
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Non-heatset Sheetfed Lithography Process Flow Diagram