acid-free paper

Wood-based paper is sometimes considered low quality. On the other hand, high quality cotton-based materials are also called acid-free or museum quality. When wood-based paper matting is used, it fades and yellows pictures over time because of the acid within the paper itself. So, when preserving mementos such as photographs in scrapbooks or picture frames, acid-free paper should be considered for matting or backing.

The purpose of good framing is not only to display memorabilia, but to preserve and protect. Unfortunately, acid-free paper costs about twice that of wood-based paper. Memories are precious though, and a little more money spent now will save more than having a picture restored in just a few years.

Paper produced before about 1850 was generally made from bleached cotton rags, a process which results in acid-free paper. Paper produced since 1850 is almost always wood-based (i.e. made from wood pulp). Wood-based paper has a high acidity and, consequently, deteriorates fairly quickly.

This truly epochal change in the paper manufacturing process explains why books and other paper documents produced prior to 1850 are often still in better condition than those published shortly after 1850.