Biodeterioration of miniature paintings from the 18th and 19th centuries

European miniature (30 to 40 mm X 40 to 70 mm) paintings were painted on ivory or on papermash using mainly natural colors, fitted in a metal frame and protected by cover glass. The casing allows penetration of air making the miniature amenable to biodeterioration if exposed to humidity. This paper describes the microbial propagation observed by microscopic methods on miniatures of the Sinebrychoff Museum collection, dating to 18th and 19th centuries. The investigation was made when the casings were first time opened after storage under variable conditions. Microscopic structures recognisable as fungal filaments, conidiophores and actinobacterial hyphae were detected in patchy distribution, suggesting that different colors may have been differently sensitive to microbial attack.