Wet and Dry Printing - What's the difference?

In a recent "Refresher Course" column that appears regularly in Linn's Stamp News, Janet Klug writes about wet and dry printing of stamps.

Klug pens, "Wet printing and dry printing are terms used primarily in intaglio printing, which is also known as engraving, line engraving or recess printing. That is the method of production that involves a softened metal plate onto which a human engraver or a machine has carved a design."

According to Klug, in a effort to speed up the traditional printing process "paper was dampened prior to being run through the printing press up until the time of highly mechanized printing. There was good reason to do this. Dampening the paper softened it a bit and made the ink adhere better. But the added moisture made the stamp image not quite as crisp as it could have been. Additionally, a bigger problem was that as the stamps dried they would shrink. Sometimes the shrinking was negligible, other times it was significant."

"When mechanized printing came on to the scene," Klug writes, "the dampened paper caused problems. It was softer, and large rolls of paper used in mechanized printing would tear if wet. Wet paper took longer to dry, made less crisp images and shrank. Printing directly on dry paper solved many problems associated with wet printing. The image detail was improved, there was no shrinking and the machinery used for printing was not compromised."

Shown above, wet and dry printings of the United States ½¢ Benjamin Franklin stamp from the Liberty Issue series.

To learn more, click here.