By about 1400 it become a relatively common medium for little volumes of sermons, cheap textbooks, popular tracts, and so on. As late as 1480 a ruling of the University of Cambridge stipulated that only books on parchment could be accepted as security for loans. Paper was evidently thought to be too insignificant. It was the invention of printing in the I450s which transformed the need for paper, and by the later fifteenth century it had become so infinitely cheaper than parchment that it was used for all but the most luxurious books. Medieval paper was made from linen rags.
Rag paper is manufactured as follows.
White rags are sorted and washed thoroughly in a tub pierced with drainage holes and they are then allowed to ferment for four or five days. Then the wet disintegrating pieces are cut into scraps and beaten for some hours in clean running water, left to fester for a week, beaten again, and so on, several times over, until the mixture disintegrates into a runny water-logged pulp. It is then tipped into a huge vat. A wire frame is scooped into the vat, picking up a film of wet fibres, and it is shaken free of drips and emptied onto a sheet of felt. Another layer of felt is laid over it.