Designs on sheets of paper created by varying paper thickness.
A real watermark occurs when the dandy roll displaces (light watermark) or concentrates (shaded watermark) the pulp mass in the wire section of the paper machine.
Facsimile, or impressed, watermarks are made in the paper web after it has left the wire section.
Imitation watermarks are added off machine by means of a transparent varnish or embossing process.
Translucent letters or a design in a sheet of paper. Usually can be seen only by holding the sheet to the light.