Page - 281 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

Sophie Rabitsch, Christa Hofmann, Junko Sonderegger 281 We wanted to use only emission free archival materials of long-term stability for the housing of the Vienna Genesis. The Japanese tissues and small packages of matboard, cor- rugated board and double-sided adhesive tape were Oddy tested at the Conservation Sci- ence Department of Kunsthistorisches Museum Vienna. All materials were classified as suitable for permanent use60. The sink mats are stored in archival boxes made of corrugated board (Klug). Each box contains three folios. Small coupons of silver, copper and lead were added to each box. They function as a small long-term Oddy test, to monitor for the potential evaporation of volatile organic compounds within the boxes. A powder-coated metal archival cabinet (Schäfer) houses the boxes in the climate-controlled high security storage room of the Department of Manuscripts and Rare books. The climate of the storage unit is 20 °C and 45 % RH. The parameters are adjusted to the range of different objects and material com- binations stored in this place. Conclusions During the initial testing of conservation materials, Berlin Tissue proved to be the most suitable paper for mending cracks, tears and losses on the folios of the Vienna Genesis. Small pieces of Berlin Tissue were toned with Schmincke Horadam watercolours using a brush to make the mends less visible on the purple parchment and the dark silver ink. Berlin tissue was coated with the hydroxypropylcellulose-ether Klucel G (5 % in water) on a matte silicone support. The Klucel coating was reactivated with a 3:1 v/v mixture of etha- nol and water, which allowed enough time for accurate placement of the mends. Experi- ence showed that the adhesive coating was strong enough for the reinforcement of tears, cracks and losses, given future restrictions in handling. These described methods were suc- cessfully applied to all folios of the Vienna Genesis. The remoistenable tissue proved to be flexible and visually unobtrusive on different areas of the manuscript. The mends can be mechanically removed with a scalpel if needed. Localized areas of fragility in the paint layers were consolidated with isinglass (1.5–2 % in water, w/v). The conservation treatment tried to balance stability of the folios with minimal changes of aesthetics and authenticity. All folios were stored in double folders of custom-made Japanese paper and in sink mats, which consist of an inner and outer mat. No adhesive, tension or pressure had to be applied and the folios can be seen from both sides. The imperatives are that the manuscript will not be exhibited and access is strictly limited. The folios will only be handled by con- 60 Sabine Stanek, Kunsthistorisches Museum Vienna, 2018, internal report. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0