A discoloration, it is characterized by brown spots on works of art in books, prints, paintings, etc., due to dampness, and mold. Bleaching processes can remove these stains. Source: Ralph Mayer, "A Dictionary of Art Terms and Techniques"<br><br>The development of patterns of brown or yellow splotches (stains) on old paper. Caused by a type of mold, foxing is often removed by treating with diluted bleach.<br><br>A brownish yellow, patchy discoloration of paper caused by the action of mold on iron salts, which are present in most paper. Foxing usually results from high relative humidity ? typically when a work is hung on a damp wall. To prevent foxing, mount, mat, and frame using only acid-free materials, keep glass away from the surface of the artwork, and place in a low-humidity environment. Foxing can be treated by a paper conservator, although it is unlikely to be removed entirely by standard cleaning treatments. Also called foxed.(pr. FAHK-səng)Also see stain and stain removal.