[The first part can be found here.]
Surely one of the truly hidden joys of reading, the discovery of a watermark. Holding the page up to light to better see and following it through the volume, in the process gaining insight into the size of the paper before it was folded and trimmed.
The process is dated to 1282 and Italy (this information from Dard Hunter’s Papermaking: The History and Technique of an Ancient Craft, first published in 1948; reprinted by Dover, NY, 1978), thereby predating printing from moveable type by some two centuries.
How is it done? By making a ‘picture’ or forming text directly on wire moulds.
In the Gutenberg42-line Bible of c1450 there is a watermark of a bunch of grapes. Later, watermarking was (and still is) used to prevent or hinder forgeries, as in banknotes.