HEATSET, NON-HEATSET, AND UV/EB PRINTING

• HEATSET: In web offset presswork, using a gas- fired, hot-air oven to "set" the ink as the paper moves from the printing units to the delivery end of the press.

--overcomes the problem presented by the high speed of the web press, which does not give enough time for drying by absorption

--imparts high gloss to printing on coated stocks

--the addition of the oven makes the press longer; adds to energy requirements

--suspected by the EPA ofincreasing the emission of VOCs (volatile organic compounds)

• NON-HEATSET (a.k.a. "coldset"): Printing on paper that does not need heat in order to dry properly. Web presses set up to run publications on uncoated paper do not need the oven, because uncoated paper is absorbent and dries readily.

• UV/EB: Setting web-printed ink by "curing" it with ultraviolet or electron-beam radiation.

--gives very high gloss, scuff resistance , and richness of color

--needs specially formulated inks; electric power requirements are high

--crews must be protected from UV/EB hazards

• What about sheetfed? Sheetfed lithography is by nature a non-heatset process, although a pressroom aid known as anti-offset spray powder is sometimes used to speed the drying of printed sheets.

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