The Chinese have traditionally been credited with the invention of paper, but the Arabs were the ones who, after learning the fundamentals of papermaking and improving on these techniques, began to introduce this new product to the West. This was a long and complicated process that was not completed until the second half of the thirteenth century in Fabriano, a town in the inlands of the region of the Marches, in Italy.
In all likelihood, the reason that Fabriano became the most important papermaking center in Europe can be found in the fact that it is located near Ancona, a port particularly open to commercial exchanges with the Arab world. It must also be noted that the ever greater skill shown by the growing numbers of qualified craftsmen in Fabriano led to a significant increase in the quality of the paper made here. Two important process innovations led to the rise of Fabriano as the cradle of papermaking in the modern conception of this term. One was the use of animal gelatin for surface sizing of the paper. This innovation permitted better writing on the sheet and solved the problem of aging caused by starch sizing, the main reason that chancelleries and notaries were forbidden to use paper for public deeds.
The second innovation was the invention of the hydraulic hammer pile with multiple screens (13th century) used to beat the rags, thus eliminating the stone mortar and wooden pestle, which had to be operated by hand, in use among the Arabs.
Another major product innovation in Fabriano was the use of watermarks on sheets so that when they are held up to light, these famous symbols can be seen. They were used initially to reproduce the trademark of the different papermakers. From: www.cartierefabriano.it