Seite - 263 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

Sophie Rabitsch, Christa Hofmann, Junko Sonderegger 263 Methods and testing of materials for conservation Remoistenable tissue Remoistenable tissues have been used for the stabilisation of objects damaged by iron gall ink or copper pigments. The introduction of humidity can be well-controlled and kept at a minimum. In order to prepare a remoistenable tissue, Japanese paper is coated with an adhesive and allowed to dry, and then reactivated with a suitable solvent. Other materi- als, like reconstituted parchment or goldbeater’s skin, can be coated as well11, but mostly Japanese papers are used. Important criteria are the concentration of the adhesive, the flexibility of the tissue and the adhesive, solvents for reactivation and the swelling capacity of the adhesive layer12. The repair should not be stronger than the original material. In lit- erature, different variations of adhesives are mentioned, including mixtures of wheat starch paste and methylcellulose13, Klucel G, isinglass, gelatine, Kollotex, Aquazol14 and acrylic dispersion15. In practice, remoistenable tissues are prepared by brushing the adhesive on the Japanese paper, or by placing the paper into an adhesive layer16. As a support, polyester or siliconized films are often used. Different methods of reactivation are described in lit- erature: spraying on the solvent17, placing the tissue on a damp ceramic tile18 or a sponge, reactivating with water vapour from hot water19, using a GoreTex sandwich20, applying solvent with a brush21 or a system of sponge cloth and blotting paper22. Depending on the adhesive, different solvents can be used. According to Andrea Pataki, the amount of ethanol should not be more than 50 % v/v when using a mixture of water and ethanol for reactivating isinglass, gelatine, methylcellulose or mixtures of wheat starch paste and methylcellulose23, while Claire Titus et al. suggest a 3:1 v/v mixture of ethanol and water24. 11 Pataki-Hundt, 2012. 12 Pataki, 2009, p. 68. 13 Baker, 1990; Brückle, 1996; Wagner 1996; Quandt et al., 2002, Rose, 2006; Pataki, 2009. 14 Pataki, 2009. 15 Anderson and Puglia, 2003. 16 Pataki, 2009, p. 53. 17 Jacobi et al., 2011. 18 Quandt et al., 2002. 19 Jacobi et al., 2011. 20 Pataki, 2009. 21 Pataki, 2009. 22 Van Velzen and Jacobi, 2011. 23 Pataki, 2009. 24 Titus et al., 2009. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0