At the archive yesterday, I got a nice lesson on paper durability.
Here is a document from around 1715:
Even accounting for the document being mounted on tissue paper, the paper is in pretty good shape. It's slightly yellow (it's hard to tell from my crappy cell phone camera), there are few rips, except for near the very edge, and none of them affect the structural integrity of the paper, and the paper is pretty thick. In other words, this is in pretty good shape for something that has been bouncing around for about 300 years. It will probably continue to last. While I'm not a paper expert, this was probably produced with cotton rags and straw, and was most likely handmade, which allowed for long, strong cotton fibers.
Here is a document from the 1840s (I think it's 1846, but I could be wrong. I'm not at the archive now):
The paper is thinner than the paper from 1715, and the paper is fragile. There is a tear that affects the structural integrity of the paper (in fact, another page of this document is nearly split in half). I had to put the paper into mylar, so this way it would not split more from handling. This would have been made after the advent of industrial papermaking, but before wood pulp was used (it was used for newsprint at the time, but this appears to be a diary page). In other words, this paper probably also involves cotton rags. However, industrial paper making cuts the fibers shorter, allowing for more acid hydrolysis, which causes paper to break down. This is apparent in this example.
Moral of the story: if you want your paper to last better for 300 years, hand make your paper with cotton rags.
