Seite - 172 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

172 Alteration study of silver inks on parchment slowly flowed into the water line which had been drawn with the bamboo pen. The ink could be burnished without being damaged by the agate polishing stone. When ST10 was dry, it had a dark greenish-grey colour (Fig. 18). Reference ink ST11 The recipe of reference ink ST11 is based on Trost’s recipe MC L a (paragraph 1) (variation 1, model 82)40 which has its origins in the Mappae Clavicula and can be dated to the 12th century. Since ST11 contains copper(II)acetate (CuAc2) next to silver powder like ST10, the reference ink is categorised as silver ink with an additional metallic component. In contrast to reference ink ST10, the silver powder was obtained by grinding 80 mg of silver leaves by hand using gum arabic as grinding aid. After the refinement of the silver, it was washed three times and then dried. The gained silver powder was transferred into a mortar and ground together with 79.5 mg of CuAc2 and 1 ml of water for five minutes. As was the case for ST10, silver and CuAc2 repeatedly separated into two phases and had to be stirred frequently to obtain a homogeneous ink. The ink could be applied to the parch- ment by the bamboo pen easier than ST10. It was more opaque, but it tended to smear when it was burnished. The colour of the dry ink was light silver to grey (Fig. 19). 40 Trost, 1991, p. 182. Fig. 18: Sample ST10_A, the sample is made using the medieval style parchment by David Frank. Fig. 19: Sample ST11_A, as described in fig. 18. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0