CRITERIA FOR TREATMENT: REVERSIBILITY
1. AIC Code of Ethics, section II. E.: “PRINCIPLE OF REVERSIBILITY. The conservator is guided by and endeavors to apply the ‘principle of reversibility’ in his treatments. He should avoid the use of materials which may become so intractable that their future removal could endanger the physical safety of the object. He also should avoid the use of techniques the results of which cannot be undone if that should become desirable.
2. R. L. Feller, “Standards in the Evaluation of Thermoplastic Resins,” Paper presented April 16, 1978, Fourth Triennial Meeting, ICOM Committee for Conservation, Zagreb. The following is adapted from this article:
3. It has been noted (C. V. Horie, “Reversibility of Polymer Treatments,” p. 3–2 in Resins in Conservations, Proceedings of the Symposium, Edinburgh, 1982) that it is likely that no treatment is reversible on the molecular level. When traces of modern materials might interfere with sophisticated analytical methods, this is significant. In terms of future treatments, however, this caveat can be disregarded.
4. Gerry Hedley, unpublished article, “On Humanism, Aesthetics and the Cleaning of Paintings,” January, 1985.
5. C. V. Horie, “Reversibility of Polymer Treatments,” pp. 3–1 to 3–6, in Resins in Conservation, Proceedings of the Symposium, Edinburgh, 1982, The Scottish Society for Conservation and Restoration. As a test of the reversibility of consolidation treatments, modern earthenware was impregnated with polymethyl methacrylate. It was then washed in acetone in a Soxhlet extractor for eight hours. About 50% of the resin remained.
6. R.L. Feller, M. Curran, “Changes in Solubility and Removability of Varnish Resins with Age,” AIC Bulletin 15#2 (Summer, 1975): pp. 17–26.
7. One kind of object which illustrates a difference in reactivity of a material with and without abrasion is plaster sculpture. Cleaning the surface of plaster with damp cotton can produce easily observable loss of surface detail. However, long-term soaking of plaster sculpture in water is a common approach to the treatment of these pieces.
8. Personal communication with Robert Feller.
9. Jane L. Down, “Adhesive testing at the Canadian Conservation Institute, past and future,” IIC Paris Conference, 1984, p. 20: “the polyvinyl acetate emulsions…are insoluble.” Rachel Howells et al., “Polymer dispersions artificially aged,” IIC Paris Conference, 1984, p. 39: Changes in solubility are discussed, although the authors note, “Strictly speaking, the method [of testing] assesses removability rather than solubility.” Many other authors (e.g., E. De Witte et al, “Influence of the modification of dispersions on film properties,” IIC Paris Conference, 1984, pp. 32–35) do not make the distinction. Removability as these material scientists have defined it in a laboratory setting is, of course, very different from removability in a practical treatment context.
10. Rachel Howells, ibid.
11. R. L. Feller, “Polymer Emulsions,” Bulletin, IIC-AG 6 #2, (May, 1966), p. 27.
12. See Paul Himmelstein, “A Re-examination of Sewing Used in the Treatment of Textiles,” pp. 33–34, and Pat Reeves, “Re-examining Textile Conservation Techniques,” pp. 35–38 in Textile Treatments Revisited, The Harpers Ferry Regional Textile Group, Symposium, November 6 & 7, 1986.