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Woe is UV

March 31, 2013

UV curing is wonderful — but it can be challenging to keep the press ’ back cylinder clean . Some blame the ink/fountain solution balance for allowing ink to accumulate on the blanket outside of the stock area. Even the slightest incompatibility results in small ink deposits outside the paper area that are then transferred to the impression cylinder and cured when the UV light hits it.

If this ink is left there for a few jobs, its physical height can damage the blanket. So how do you remove that baked-on ink? Popular (albeit timeconsuming) methods involve alcohol and Scotch Brite pads, blanket wash and steel wool, methylethylketone, razor blade and solvent, acetone, and methylene chloride.

In most cases, using an abrasive results in scratching and metal loss. If you attempt to resell the press, the damage will stand out like a sore thumb during the inspection.

Management may roll their eyes, but the proper approach is to cut blanket packing to just under the size of the stock being printed. (Some printers use a strippable blanket and cut the blanket, but this is an expensive solution.)

Admittedly, it’s time consuming to cut packing and mount it for each stock size change. Opening up a large-format press and hanging a new packing does take time, and wrinkles can occur if thin packing paper is used. Some savvy printers have packings cut for every size of sheet run and store them by the press. Bonus: Running thick board or plastic eliminates the need for packing because the blanket won’t contact the back cylinder.

Weigh your options if you’ll be doing a lot of short-run work on a sheetfed UV press. Changing packings for every job is impractical. Plan ahead—the alternative is good old-fashioned elbow grease. Not to mention a lot of time! Raymond J. Prince, President, GreensheetBIZ (Retired), a division of OutputLinks Communications Group, is a leading pressroom technical expert. Talk to Ray at B2Me.me/AC2

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