Byne's disease

Byne's “disease” is an efflorescence of calcium acetate and calcium formate crystals on calcareous shells, corals, eggs and some fossils. It appears as a fine white powder or glassy crystals, often with a vinegar smell. The cause is acetic and formic acid vapour given off by oak, other hardwoods, plywood, MDF, cardboard, and some adhesives and paints, trapped in a closed drawer with a little humidity. The acid reacts with the shell's calcium carbonate and slowly dissolves it.

Prevention is the storage material. Use powder-coated steel cabinets or drawers lined with archival (buffered, lignin-free) board and polyethylene foam; avoid oak entirely; let new wooden furniture off-gas for months before it holds specimens; keep humidity moderate and give closed cases occasional ventilation.

Treatment is washing. Rinse affected shells in clean water (distilled for delicate pieces), brush gently, dry thoroughly, and re-house in inert materials. Etched surfaces do not recover, and the specimen's appearance is now part of its history: note the episode on the record.

Fossils with original shell material (many ammonites, brachiopods and gastropods) are vulnerable in the same way; permineralised material generally is not.