Seite - 265 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

Sophie Rabitsch, Christa Hofmann, Junko Sonderegger 265 integrates well with purple parchment and dark ink. However, because of its thinness, Berlin tissue is difficult to colour and tears easily when wetted. After further investigating the production process and the ingredients, we decided to choose a modified form of Ber- lin Tissue. KR4C is produced by different companies, is already dyed and can potentially contain residues of a wide range of chemicals. Berlin Tissue is produced with Acryperse25 as a lubricant. As we wanted to eliminate the risks of residues of Acryperse in the tissue, we asked Gangolf Ulbricht to produce a Berlin Tissue using Aloe Vera instead of Acryperse especially for this project. RK0 and KR4C were used for the tests because of their lower cost and availability in larger quantities at the Institute of Conservation. Adhesives Different adhesives, which are suitable for the use as a remoistenable tissue and can be reactivated with non-aqueous solvents, or a mixture of water and a non-aqueous solvent, were considered and selected for advance testing. The adhesives should have good ageing and bonding properties. They should be flexible and have a matte surface. Furthermore, it should be possible to remove the mends and to retreat the folios, if necessary. The following adhesives were selected for testing: - Gelatine (Photogelatine Gelita, Restoration 1 GMW, Type B 264g/Bloom)26 - Isinglass (Störleimmanufaktur)27 - Parchment glue (Kremer)28 - Hydroxypropylcellulose-ether Klucel G (Kremer)29 - Methylcellulose Methocel A4M (Kremer)30 - Wheat starch paste (Nebel)31 25 Acryperse is a polyacrylamide, used to improve dispersion of the fibres in the papermaking process. 26 The gelatine powder was mixed with deionized water (2.5 and 5 %), warmed in a double boiler and stirred from time to time, until it was fully dissolved. 27 Pieces of adhesive film (2.5 and 5 % w/v) were mixed with deionized water, warmed in a double boiler and stirred from time to time, until the film dissolved. 28 Pieces of adhesive film (2.5 % w/v) were mixed with deionized water, warmed in a double boiler and stirred from time to time, until the film dissolved. 29 The powder was mixed with deionized water or ethanol (2.5 and 5 % w/v), stirred and left to stand in the refrigerator for approx. 12 hours, after which the powder was fully dissolved. 30 The powder was mixed with deionized water (2.5 % w/v), stirred and left to stand in the refrigerator for approx. 12 hours. The next day the powder was fully dissolved. 31 The mixture of 24 % wheat starch paste in water w/v was heated while being stirred, until it had a glassy appearance. It was left to cool and pressed through a sieve. Afterwards, it was mixed 1:2 v/v with water. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0