Foxing
Small reddish-brown spots that appear on aged paper, caused by humidity, oxidation, and trace iron impurities. Common on older prints; preventable on modern archival paper.
Foxing is the name for the small reddish-brown or yellowish spots that develop on older paper over time. The spots cluster across the surface, sometimes in patches, sometimes fairly evenly. Each one is a few millimetres across; collectively they give an old print a freckled, blotchy appearance.
The exact cause is debated. The most likely combination of factors is humidity, oxidation, and traces of iron or other metals in the paper itself. Mould may also play a part — some foxing spots show fungal traces under a microscope, others don’t. What’s not in doubt is that foxing develops over years or decades of exposure to fluctuating humidity, particularly when prints are stored in damp environments or unframed in cellulose-rich folders.
Modern archival paper is much less prone to foxing because it’s manufactured with deliberately low metal content, controlled pH, and acid-free buffering. A print on 100% cotton rag or α-cellulose paper, framed with UV-filtering glass and kept in a stable environment, should remain foxing-free indefinitely.
Three things make foxing more likely. High humidity — anywhere above about 65% relative humidity for prolonged periods, which is why bathrooms, kitchens and unheated rooms are the usual culprits. Direct contact with cardboard, wood, or non-archival mounts, which transfer acidity to the paper over time. And long-term storage rolled in tubes without humidity control; better to store flat in archival sleeves.
If you spot foxing on an older print, a professional paper conservator can sometimes bleach or chemically reduce the marks, though there’s always a risk to the surrounding paper and inks. Better to prevent than to treat. Our prints ship on Hahnemühle 310gsm and frame with UV-filtering acrylic, and with sensible placement they’re as foxing-resistant as the materials allow.