RAG PAPER • FREE TRANSLATOR.ORG • Definition of Rag paper

... to have been invented by the Chinese at an unknown but very early date. It was introduced to Europe by the Arabs about the 10th century A.D. It was made of linen or rags and did not vary greatly from the rag paper of to-day. As the process of manufacture is fully described in the book on paper (No. 13) of this series, description is not necessary here. Paper was not much used in Europe until the invention of printing. Being much less substantial than vellum it did not commend itself for the making ...

— Books Before Typography - Typographic Technical Series for Apprentices #49 • Frederick W. Hamilton