Watermark is a translucent design impressed on paper during manufacture and visible when the paper is held to the light. This is mostly used in currency notes, passports, and postage stamps. It is used as a security feature. Watermark is created in papers to prevent counterfeiting. Watermarks vary greatly in their visibility. Some are obvious on casual inspection, and others require some study to pick out.
The mill seems to have been a prominent and impressive riverside feature:
This is so fine with workmanship set foorth
So surely built, and planted in the ground
That it doth seeme a house of some estate
To which brave mill do thousands still repayre
So see what things are wrought, by cunning skill,'
Churchyard's poem gives some indication of the paper making process employed at Dartford : A Paper-mill
That now neere Dartford standeth well
Where Spilman may himself and household dwell
The Mill itself is sure right rare to see
The framing is so quaint and finely done
Built of wood and hollowed trunks of trees
The Hammers thump and make so loud a noise
As fuller doth that beats his woollen cloth
In open show, then Sundry secret toyes
Make rotten rags to yield a thickened froth
There it is stamped and washed as white as snow
Then flung on frame and hanged to dry, I trow
Thus paper straight it is to write upon
As it were rubbed and smoothed with slicking stoneThe Dartford-based mill was granted extensive monopoly powers that were often the subject of dispute.
By the time that printing from moveable types is developed in 1450, the tradition of watermarking paper is already two centuries old (Hunter 1943, 261)
The term water mark is fairly modern.
Several theories have been proposed.
Identification Marks- like Trademarks of today.
This seems unlikely since there were so many more watermarks than papermakers.