The two types of offset presses you might use to print the books, brochures, posters, etc., that you design are sheetfed presses and web presses. The difference has to do with the format of the paper used in the printing process.

To feed a sheetfed press, you would load the press with a stack of individual sheets. These might be anywhere from 20″ x 26″ (for cover stock) to 25″ x 38″ or 28″ x 40″ for a text sheet. The actual measurements will depend on the dimensions of the press (you might use a 25″ x 38″ sheet in a 40″ press, for instance). The measurements will also depend on the standard format in which the paper mill provides the paper (a text sheet is customarily provided in 25″ x 38″ format, but you can also order a 28″ x 40″ sheet in many cases). Or, your printer may trim down a larger sheet (a parent sheet) to fit his press.

In contrast, a web-fed offset press uses rolls of paper (which are usually cheaper for the paper mill to produce than cut sheets since they have not yet been trimmed to their final size).

In the majority of cases a printer can order a particular paper stock (a particular weight, paper surface, and color) in either rolls or sheets, depending on the press he plans to use. In some cases, however, a printer will trim paper before the press run using a “roll sheeter.” This is a device that chops a continuous roll of paper into multiple sheets (think of a roll of perforated paper towels, which starts as a roll but yields sheet after sheet of paper for your cleaning needs).

When loaded on a large web press, a roll of printing paper provides a continuous stream of paper, which flows through the inking units of the press at a much faster pace than individual sheets travel through a sheetfed press. The ink units deposit offset ink on the plates, as with a sheetfed press, and the plates transfer the ink to the press blankets and from there onto the paper. Finally, cutting and folding equipment folds the web of paper into signatures or cuts the ribbon of paper into flat sheets, which may then be further processed.

Web presses and sheetfed presses focus on different print run lengths. In most cases, sheetfed presses are used for shorter runs, while web offset presses are usually saved for longer runs. Printed products from sheetfed presses are often of a higher printing quality than those produced on web presses; however, web presses have been improving in leaps and bounds and now come very close to sheetfed offset in the quality of their output.