What is: Watermark ?

A term which is used to refer to the impression of a pattern, design, or symbol in a sheet of paper while the paper is being produced in the paper machine wire. It appears as either a darker or lighter area than the rest of the paper in the finished sheet. There are two types of watermarks which are available: the wire mark and the shaded watermark. The wire mark is gotten by impressing a dandy roll into a moving paper web similar to a shaded watermark. This creates a lighter area as a result of less fiber being used. A shaded watermark, on the other hand, is produced by a dandy roll which is found at/near the suction box on a Fourdrinier. The design is then pressed into the wire which covers the surface of the dandy roll. As wet pulp begins to move along the web, there is an accumulation of fiber such that the watermark becomes darker than the rest of the paper sheet.
There are different placement styles of watermarks. A random watermark which is the cheapest to create randomly appears repetitively throughout the sheet. A localized watermark, however, is one that appears in a position that's has been determined. A staggered watermark has several watermarks on each sheet of paper in the desired fashion. Lastly, a paraded watermark appears either vertically or horizontally in a line on each sheet of paper. There are different placement styles of watermarks. A random watermark which is the cheapest to create randomly appears repetitively throughout the sheet. A localized watermark, however, is one that appears in a position that's has been determined. A staggered watermark has several watermarks on each sheet of paper in the desired fashion. Lastly, a paraded watermark appears either vertically or horizontally in a line on each sheet of paper.