The image is impressed farther into the sheet during couching. By the mid-nineteenth century, papermakers were no longer limited to the linear watermark designs created with traditional bent wire. Gradations of tone are realized because of small differences in the density or thickness of the paper pulp from one image area to another. As with watermarks made using wire, these images are seen best when backlit. This type of watermark was commonly used for currency, since the effect is hard to reproduce.
Chiaroscuro watermarks start with a sculpted design.
A relief sculpture, generally made of wax, is the model for a die and matrix. These give shape to a fine wire mesh that is attached to the screen of a papermaking mould. This shaped area of the screen collects varying amounts of pulp as the fiber settles when a sheet is pulled. Modern papermakers continue to employ the traditional methods outlined above while experimenting with newer techniques, such as photo-etched magnesium watermarks. Copyright 1997, Hand Papermaking, Inc.