Foxing

Foxing is an age-related process of deterioration that causes spots and browning on old paper documents such as books, postage stamps and certificates. The name may derive from the fox-like reddish-brown color of the stains, or the rust chemical ferric oxide which may be involved. Paper so affected is said to be 'foxed'. Foxing is an age-related process of deterioration that causes spots and browning on old paper documents such as books, postage stamps and certificates. The name may derive from the fox-like reddish-brown color of the stains, or the rust chemical ferric oxide which may be involved. Paper so affected is said to be 'foxed'.