Watermarks served as trademarks, identifying the mill or the maker, and sometimes indicated the size or quality of the sheet. Because watermark designs changed over time and differed from mill to mill, they later became valuable evidence for dating old documents.
From Italy, papermaking spread to France, to the German lands, and onward. A paper mill was established near Nuremberg in 1390, and its founder kept a record of its operation that survives. Mills appeared in the Low Countries and in Switzerland. In England, the first known mill was established in the late fifteenth century, though English production remained modest for a long time, and much of the paper used in England was imported. By the time printing with individual metal letters was developed in Germany in the middle of the fifteenth century, paper was available in sufficient quantity and at a sufficiently low price to make the large-scale printing of books practical.
V. The European Mill
A paper mill of the sixteenth or seventeenth century was a busy establishment that combined heavy machinery driven by water with work requiring great manual skill. Its raw material was rags: worn-out linen and, later, cotton cloth, collected from households and sold to the mill by rag merchants. The supply of rags was so important that some governments regulated their trade and forbade their export.
At the mill, the rags were first sorted by fiber, color, and condition. Buttons, hooks, and seams were removed, and the cloth was cut into small scraps. The scraps were then often left damp in heaps for several weeks to ferment, a process called retting, which loosened the fibers and made them easier to beat. Retting produced heat and a strong odor, and it required careful judgment, since too much fermentation weakened the fibers and too little left them hard to break down.
The retted rags went to the stamping mill. A large water wheel drove a shaft fitted with projecting cams. As the shaft rotated, the cams lifted a series of heavy wooden hammers and let them fall into troughs where the rags lay in water. Fresh water ran continuously through the troughs, washing away dirt. The hammering went on for many hours, first with hammers fitted with iron to break the rags apart, and then with plain wooden hammers to separate the fibers more finely. The sound of the hammers, working day and night, was a familiar feature of mill districts.
The finished pulp was carried to the vat, a large tub of warm water in which the pulp was kept in suspension. The vatman, the most skilled worker in the mill, formed each sheet using a mould and a deckle. The mould was a rectangular wooden frame covered with a screen of fine wire. In the most common type, the screen was made of many closely spaced thin wires running in one direction, supported by thicker wires spaced farther apart in the other direction. These wires left a pattern of fine lines in the sheet, visible when it is held up to the light, and paper made on such a mould is called laid paper. The deckle was a removable wooden rim that fit around the edge of the mould and held the pulp in place, setting the size of the sheet.
The vatman dipped the mould and deckle into the vat, lifted them out level with a layer of pulp, and gave them a quick, controlled shake from side to side and from front to back. This motion caused the fibers to interlock in many directions as the water drained through the wire. The thickness and evenness of the sheet depended on the vatman’s skill in taking up exactly the right amount of pulp and spreading it evenly.