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Course: Cleaning of polychrome surfaces by using methods alternative to toxic solvents
The course on cleaning of polychrome surfaces by using methods alternative to toxic solvents (Easel paintings and paintings on wooden support, wooden polychrome sculptures) was held in the Conservation Department of the Croatian Conservation Institute in Dubrovnik from 20 to 24 October 2008. The lecturer was Mr. Carlo Lalli from the Chemical Laboratory of Opificia delle Pietre Dure.
The course is designed to provide the study of general, organic and inorganic chemistry completed with the characteristics of natural and synthetic adhesives, glues and varnishes, taking in consideration chemical and physical characteristics of old and modern adhesives and varnishes. Various types of solvents were studied focusing on the capacity of dissolution, the evaporability, the retention, the toxicity, as well as the possible alternatives to toxic solvents. The solubility of materials and the capacity of dissolution of solvents were also studied using the relative triangle of solubility as well as the principles and characteristics of the Feller and Wolbers tests. Regarding the alternative methods of cleaning the course covered the following topics: water methods and chemical-physical characteristics of tensides, chelates, saliva and enzymes. Other topics were: studying the characteristics of thickeners, condensed solutions and buffer solutions in cleaning with water methods. The importance of controlling pH and electronic conductivity of solutions during the cleaning was emphasized.
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