For the copyright prosecution term, see Foxed

Foxing is a term describing the spots and browning seen on old books, documents, postage stamps, and so forth. The name is believed to derive from the fox-like reddish-brown color of the stains.

While unsightly, and a negative factor in the value of the paper item for collectors, foxing does not affect the integrity of the paper.

Causes of Foxing

The causes of foxing are not well understood. One theory is that foxing is caused by a fungal growth on the paper. Another theory is that foxing is caused by the effect on certain papers of the oxidation of iron, copper, or other substances in the pulp or rag from which the paper was made. It is possible that multiple factors are involved.

It is believed that high humidity contributes to foxing.

Repairing foxed documents

There is a product called FOXIT to remove foxing. The problem with using proprietary bleaches to remove foxing is that they invariably affect the integrity of the paper and the paper has to be subsequently resized.

The question of using laser-based techniques to remove foxing stains from old paper is a potential solution to the problem. The use of lasers however, at longer wavelengths, is usually accompanied by side effects, since the affected areas requires higher laser energies^* to be cleaned.

There is also an aqueous method by Paul Tronson (not for commercial use) for removing foxing without damaging the integrity of the paper or any media and which removes mildew spores and fungi.

References

• Roberts and Etherington, Bookbinding and the Conservation of Books
• Antique Roadshow: 'Antiques Speak'
• The Library of Congress: 'Preserving Works on Paper'

Pulp and paper industry | Philatelic terminology | Postal markings