What is a watermark?
A watermark is a moulded object. A sheet of paper is a moulded object too, made by a liquid paste in a vat and modelled on a wire rack (paper mould).
A sheet of paper showing a watermark in transparency is a doubly moulded object or, more precisely, an object moulded in two times: a wire has been modelled on a pattern to shape the watermark, and the watermark has been fastened on the mould which makes the sheet of paper at the vat.
Typical of the Western paper, watermarks start to appear by the end of 1280s, in Italy. They are used to mark a sheet of paper, signifying its size, its quality or the papermill of origin. Complexity arises as time goes by: watermarks change their position on the sheet of paper, countermarks begin to appear to complete the marking of the sheet, patterns are reused and modified to preserve the distinctive quality of the mark.
Being part of the final mould which makes the sheet of paper, a watermark cannot be analysed without taking into account the sheet of paper marked by it. It is a bidirectional relationship: the watermark identifies the ream of paper and the ream of paper identifies the watermark. In front of one sheet of paper whose datation and localisation are unknown, the watermark becomes an useful element, provided that the whole sheet of paper is taken into account, because the same pattern could mark different reams, produced at different times.
Vocabulary of the watermark
- Deckle = wooden frame which delimits the paper mould while dipping in the vat.
- Vat = the container for the liquid paste of plant fibres, where the paper sheets are made by the two-man team.
- Vatman = the worker who dips the paper mould in the vat.
- Coucher = the worker who reverses the sheet of paper coming out from the vat on the post.
- Post = the pile of sheets made at the vat, put one over the other, alternately with the felts.
- Felt = piece of tissue interposed between two sheets of paper freshly made at the vat.
- Mould = metallic structure, letting its imprint on the sheet of paper, made by:
- rib = wooden triangular support, parallel to the short sides of the mould.
- chainline = wire knotted or bound perpendicularly to the wirelines, in order to fix them, usually in correspondence with a rib.
- supplementary chainline = wire knotted or bound perpendicularly to the wirelines, not in correspondence with a rib, usually used to fix better the watermark.
- wireline = wire made by an alloy of copper or bronze, aligned in a series of wires parallel to the long sides of the paper mould.
- tranchefile = tiny wire put between the last chainline and the short edges of the mould, without any supporting rib.
Here is the vocabulary in pictures, to show the steps of making watermarks and sheets of paper: