A page foxing story
A page foxing story is a short explanation as to the term “foxing” which is used to describe the shades of brown staining found on old printed products. It doesn’t affect its integrity but does lower the value of the document for collectors. It is thought to be caused by either fungus or the oxidising of iron and other trace metals.
For a more information about caring for books have a look at this interesting article from the Victoria & Albert Museum in London, UK.