by: Corinne Cain

Foxing is a condition flaw on a work on paper.

Foxing yields a freckled appearance typically of red brown spots. Currently it is believed these are iron oxides and hydroxides produced by the chemical reaction between the organic acids discharged by mold and the colorless iron salts and impurities embedded in the paper.

Dampness encourages mold. Some types of sizing in the paper also attract fungus growth. Acidic contact materials such as cardboard and animals glues can aggravate the foxing.

Only a professional paper conservator can minimize the appearance of foxing safely.

To read more on this topic, I suggest The Care of Prints and Drawings by Margaret Holben Ellis as well as Prints and The Print Market by Theodore B. Donson.