What Is a Watermark?
A watermark is an identifying image or pattern in paper which is very useful in the examination of paper as it can be used for dating, identifying sizes, mill trademarks and locations, and determining the quality of a sheet of paper.
If you hold a piece of writing paper up to the light you may see lettering or a design of some kind. Such markings are called “watermarks.” Watermarks are trademarks which paper makers put in quality writing paper.
There are two main ways of producing watermarks in paper; the dandy roll process, and the more complex cylinder mould process. Using the dandy roll process, when the paper is being made, it passes under a roller on which is fastened the watermark design.
The design presses into the soggy paper, leaving it a tiny bit thinner where it comes in contact with the design. When the paper dries, the watermark becomes translucent.
Watermarks are sometimes put in postage stamps and paper money to prevent counterfeit printing.