Print Process Descriptions: Printing Industry Overview: Lithography

Non-heatset Web Offset Lithographic Printing

The non-heatset web offset process is a high speed process used largely in the production of newspapers, journals, directories, and forms. In non-heatset web lithography, the paper or paperboard substrate is delivered to the facility in rolls. The paper is fed directly into the press from the roll and is termed a "Web" since it is a continuous feed of paper as opposed to individual sheets. After printing, the paper is folded and/or cut "in-line" with the printing units.

Non-heatset lithographic inks are paste inks that dry by oxidative polymerization and adsorption into the substrate, rather than evaporation therefore they typically do not require mechanical, and thus, the VOC emissions generated during the use of this printing process are quite small. Dampening and inking systems (including dampening chemistry and ink formulations) differ significantly from heatset web offset. The other major chemicals used in this process, such as fountain solution cleaning solvents, etc. are quite similar to those used in heatset web offset.

Finishing:

After printing, the substrate may run through a number of operations to be "finished and ready for shipment to the customer. Finishing may include operations such as coating, cutting, folding, binding, stitching, embossing, and die cutting.

Non-heatset Web Lithography Process Flow Diagram