Seite - 273 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

Sophie Rabitsch, Christa Hofmann, Junko Sonderegger 273 to tear quite easily when wet. RKO was quite difficult to handle and it was not possible to dye the delicate and thin Berlin Tissue. The vivid colour that resulted was very different from that described by the company. A large series of tests with a range of colours would have been necessary to achieve subtle purple hues. We decided to use watercolours (Schmincke Horadam), as they give good results in col- our and the Japanese tissue keeps its delicate character (Fig. 28). The watercolours are easier to mix and to apply than the cold water dyes. Schmincke Horadam watercolours meet the demands of stability and lightfastness52 and are often used in conservation. When too much colour is applied, the remoistenable tissue can stain a bit when reactivated with a larger amount of water and left on the wet blotting paper too long. Applying the colour only works with smaller pieces of Japanese tissue (max. 10 x 10 cm), otherwise the paper tears apart easily. Before the application of the adhesive, the margins of the pieces of the coloured Berlin Tissue were cut, as the watercolours tend to accumulate in these areas and can stain. The Oddy Test53 performed on coloured Japanese tissues showed that they are suitable for permanent application. table salt (NaCl) in a tray and stirred. The Japanese tissue (RK0, approx. 7 g) was immersed flat on a polyester web support and left in for around 40 minutes. Afterwards, it was immersed into a water bath and rinsed with cold water until it was clear. It was then put to dry, still on the polyester web, on a dry support. 52 https://www.deffner-johann.de/schmincke-horadam-aquarell-kompaktkasten.html (accessed 07 November 2018). 53 Sabine Stanek, Conservation Science Department, Kunsthistorisches Museum Wien. Fig. 28: Berlin tissue toned with watercolours (Schmincke Horadam). Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0