Observations on aesthetic and structural changes induced in Polish historic objects by microorganisms

During a long career at the Institute for the Study, Restoration and Conservation of Cultural Property, Nicholas Copernicus University, the author has observed that most of the objects reaching the conservation laboratories have suffered deterioration caused by microorganisms. This deterioration is due to the exposure of these historical objects at some stage of their long existence to conditions moist enough to be conductive to microbial growth. The combination of sufficient moisture and the nutrients in the materials from which historic art objects are formed provides the conditions that allow deteriorative microorganisms to survive, develop and cause damage to the objects over extended periods of time. Examples of deterioration in various museum and library items in Poland are discussed.