Foxing

Foxing

Definition

Foxing refers to the appearance of brown, reddish, or yellowish spots on paper, photographs, books, or other cellulose-based materials. These spots are typically caused by a combination of age, moisture, metal impurities, mold spores, and chemical reactions in the paper, often exacerbated by environmental conditions such as humidity and temperature fluctuations.

Causes

• High humidity and damp storage conditions encouraging mold or fungal growth.
• Oxidation of iron or other metal impurities present in the paper fibers.
• Acidic paper or mounting materials accelerating chemical reactions over time.
• Environmental pollutants or off-gassing from surrounding materials.

Prevention

• Store paper-based materials in cool, dry, and stable environments.
• Use acid-free, archival-quality mats, backing boards, and storage boxes.
• Avoid direct contact with wood, cardboard, or other materials that off-gas acids.
• Maintain controlled humidity (ideally 40-50%) and temperature (65-70°F) for sensitive items.

Related Terms

• Spores
• Deterioration
• Off Gassing
• Water Damage