There is much terminology to learn in the printing industry as there are so many facets to printing and because technology keeps changing in this digital age. Here are easy-to-understand definitions for common printing terms.
Sheetfed Press: a press that feeds and prints individual sheets of paper rather than continuous rolls used by web presses. Sheetfed presses come in a variety of sizes from very small units that one might find in a quick print shop to very large presses used for longer run and larger format needs. They can print on a variety of substrates including paper, plastics, metal and other materials. Sheetfed presses also come in a wide range of colour configurations and some are equipped with perfecting units, which enable the printing of both sides of the sheet in a single pass.
Web Press: a press in which a continuous roll (web) of paper or other substrate is fed through the printing press. Particularly in the case of web offset printing, a wide range of equipment can be attached to enable roll-to-roll finishing, sheeting, signature folding or a variety of in-line finishing techniques including perforating, gluing, die-cutting, folding and other options. Web presses are better suited to high-volume publications such as mass-market books, magazines, newspapers, catalogues and brochures, as well as direct mail.
Heatset Process: heatset web offset printing is a printing process in which ink is dried rapidly by forced-air heating. In reality, the ink is not fully dried after the web of paper passes through the ovens. Rather, oil-based solvents reach evaporation point leaving waxes, resins and pigment. The paper next passes through chilling rollers where the waxes and resins cool down and set. Finally, a layer of silicone is applied to prevent the ink from offsetting onto other parts of the press during any finishing processes. Moisture may also be added to the paper to replace what was lost in the ovens.
Coldset Process: coldset web offset printing dries the ink purely through evaporation combined with absorption into the paper. It is suitable only for uncoated, supercalendered and matte finished papers, which allow sufficient ink absorption. The majority of newspapers globally are printed on coldset presses, along with many forms, manuals, books and other products suited to uncoated papers.
Signature: a group of pages that are printed on both sides of a sheet of paper and then folded and trimmed to the finished page size. The number of pages within a signature depends upon your page size and the dimensions of the press sheet used. Publications may have multiple signatures that are gathered and trimmed on saddle stitching or perfect binding machines.
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