Autographs, as distinguished from copies and reprints, are writings which came from the pen of the author himself. As far as our present knowledge goes, the Biblical autographs are no longer in existence, although we can determine fairly well how they appeared. Like other books of the time they were probably papyrus rolls or scrolls. Papyrus was made from the pith of the papyrus plant, a long stemmed reed terminating in a large umbrella, which grew in abundance on the banks of the Nile River and in other Oriental countries. A sheet of papyrus was made of thin strips of the pith arranged horizontally and vertically and was usually six to fifteen inches in height and three to nine inches in width. The separate sheets were then glued together, dried in the sun, attached to one or two sticks or wooden cylinders, rolled up around them, thus making a roll or scroll.
Papyrus was cheap but not durable. The winding and unwinding as well as moisture soon proved destructive to the scrolls. A more durable, though more expensive, material was furnished by the skins of lambs, sheep, goats and calves. As in the case of papyrus, sheets of the leather or the parchment were sewed together to form a longer strip, and strips, in turn, were jointed together to form a roll. The copies of the Old Testament books which were used in the Jewish religious services were undoubtedly written on leather. Saint Paul had parchments with him (2 Timothy 4:13) but it is not very likely that his Epistles were written on this costly material.
The skin of a single animal furnished only a few sheets and was naturally very costly. Hence when a leather book or scroll became illegible from long usage, or when a library had too many copies of the same book, the old text was scratched or washed out and replaced by a new writing. Such copies are known as "palimpsests" (erased again). With the aid of reacting chemicals the old writing has in some instances been restored and lost texts have in this way been discovered.
Material taken from http://www.cathtruth.com/catholicbible/bookbook.htm