Seite - 169 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

Sophie Rabitsch, Antonia Malissa, Katharina Uhlir, Martina Griesser, Christa Hofmann 169 Reference ink ST7 The recipe used for the production of reference ink ST7 was based on LP X 8a/3–4 (model 9)33. The recipe has its origins in the Leiden papyrus X and can be dated to the end of the 3rd or the beginning of the 4th century A. D. Since the binding medium cherry gum is the only component of the ink next to powdery silver, ST7 is categorised as a pure silver ink. 80 mg of silver leaves were ground by hand using gum arabic as a grinding aid. The ob- tained fine silver was then washed three times and dried. The powdered silver was heated, mixed with 10 mg of cherry gum as well as with 0.5 ml of water and was further ground in a marble mortar for 10 minutes. The resulting ink was easily applied to the parchment samples using the hand carved bamboo pen and could be burnished without any smear- ing. The dry ST7 has a light grey to whitish hue (Fig. 15). Reference ink ST8 For the production of reference ink ST8, Trost’s recipe CL α 11–20 (variation II, model 49)34 was followed. The recipe originates from the Lucca manuscript and is dated to the end of the 7th or the beginning of the 8th century. Like reference ink ST7, it contains only cherry gum as a binding medium next to powdery silver and thus can be categorised as pure silver ink. Since the powdered silver is obtained by the process of amalgamation, the recipe was chosen to investigate possible effects due to this method. For the preparation of the silver powder, 100 mg of silver chips were filed off a thin silver plate, using a fine iron file. The gained silver chips were then ground in a porcelain mortar together with 300 mg of mercury (Hg) under high temperature, above the flame of a Bunsen burner. After 15 to 20 minutes small silver flakes formed. They were ground for 33 Trost, 1991, p. 70. 34 Trost, 1991, p. 129. Fig. 15: Samples ST7_A; as de- scribed in fig. 9. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0