Page - 264 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

264 Conservation of the Vienna Genesis and the new storage system Materials for mending Different materials were considered for the stabilisation of fragile areas in the parchment and the corroded ink of the Vienna Genesis. The material should be flexible and as visually neutral as possible. Furthermore, it should meet the required conservation standards and be suitable for coating including activation with no or little moisture. The following ma- terials were considered: Protein repair materials: - Thin sanded parchment: it is visually very noticeable on the purple-dyed parchment and the optics of the surface do not match. The new parchment has a tendency to cockle and is stronger than the aged original parchment. - Reconstituted parchment: the material is more flexible than sanded parchment and can be produced in the required thickness. Nevertheless, it is visually noticeable on the purple parchment due to its opaque and milky appearance. - Goldbeater’s skin: It is translucent and thin, but has a very shiny surface. The material is difficult to apply in small strips, as the skin tends to curl. Japanese tissue papers: Japanese tissue papers are thin, flexible and unobtrusive. They are easier to colour than the proteinaceous repair materials and even very small pieces of Japanese paper can be handled without problems. For mending of tears on purple parchment and the stabilisation of cor- roded silver ink, the visual effect is very important, as the appearance of the folios should not be altered. The viewer should not be distracted by whitish mends that stand out. Given these considerations, we decided to use Japanese tissue for the stabilisation of the Vienna Genesis. The following papers were evaluated: - RK0 (5 g/m2, machine made, Kozo fibres; Paper Nao) - RK00 (3.7 g/m2, machine made, Kozo fibres; Paper Nao) - KR4C (4 g/m2, machine made, Kozo fibres; Römerturm) - Berlin Tissue (2 g/m2, handmade, Mitsumata and Kozo fibres; Gangolf Ulbricht) Samples of these papers were laid on purple parchment and ink in order to evaluate their optical suitability. The papers were coated with adhesive and applied to samples of parchment. RK0 is too thick and too visible on purple parchment and silver ink. Despite its thin- ness, the fibres of RK00 are also too visible. The paper KR4C is appropriate, as it is thin, but sufficiently strong. Due to its brown hue, it is visually neutral and easy to colour. Berlin Tissue meets the requirements as well. With 2 g/m2 it is the thinnest paper but strong enough for mending. Berlin Tissue is handmade from Japanese Mitsumata and Kozo fibres, cooked with potash (potassium carbonate). With its even structure the tissue Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0