摘要：

For centuries, traditional organic fixatives, especially those based on proteins, such as case in and animal glue, oil, or even plant gums, were used in the preparation as well as restoration of wall paintings. Synthetic consolidants have come into use within the last 30 years. By experience, every restorer knows that most of the natural polymers used for consolidation can easily be degraded by microorganisms under conditions of high humidity. One of the reasons for introducing synthetic consolidants in the restoration of mural paintings was that those materials were expected to be more resistant to microbial attack. Degradation of mural paintings that had been restored by synthetic consolidants could, however, be detected by the naked eye in many cases and was more closely investigated by means of scanning electron microscopy (SEM). Microbial attack frequently occurred from beneath the material applied on the surface of the paintings. The increasing number of objects treated with, e.g., derivatives of cellulose, polyvinyl alcohol, polyvinyl acetate, and even acrylate methylacrylate copolymers, led to the investigation of the possibility of biodeterioration of synthetic consolidants. In the case of most medieval, as well as modern wall paintings from different climatic regions (north Germany to Brazil), it could be shown that the microflora, enriched from the restored objects and involved in the biodeterioration of the original paintings, were able to live on and to destroy those synthetic materials that had been applied to the specific objects during former restorations. -- AATA

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