Paper was made by hand from old rags, usually linen. The rags were allowed to rot slightly, then were chopped and pounded to a pulp in a water-driven mill. The pulp was cooked slowly until it became a paste; sheets of paper could then be made by dipping a mould into it, shaking the mould until the paste formed an even layer, and left to begin the process of drying.

As soon as it could be lifted out of the mould, several sheets of paper were put in a press, and excess water squeezed out. Since the mould was rather like a sieve, with wires running in each direction to hold the pulp, it would leave a watermark when it dried.

"Quartos", "folios" --and "duodecimos"

Paper came in various sizes: Imperial was the largest, 70 by 50 cm (29 by 20 inches), and Foolscap the smallest 45 by 31.5 cm (17.5 by 12.5 inches). The size of the resulting book depended not only on the size of the paper, but on the number of times the page was folded before binding:

name folds leaves/sides
Broadside (1o) (not folded) one leaf, two sides
Folio (2o) one two leaves, four sides
Quarto (4o) two four leaves, eight sides
Octavo (8o) three eight leaves, sixteen sides

. . . and so on, including sheets folded up to 6 times, to produce 64 (very small) leaves, and 128 pages. ("Duodecimo," incidentally, is a size that produces twelve leaves).

Quartos were often sold stitched, but not fully bound, and thus were the Elizabethan equivalent of today's paperbacks. About half of Shakespeare's plays were originally published in quarto.