Seite - 182 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

182 Alteration study of silver inks on parchment Evaluation before ageing Prior to the accelerated ageing the colours of the reference inks ranged between yellowish, greenish or brownish grey and a very light grey on purple parchment (Fig. 24 and 26). Comparing particularly the copper(II)acetate containing reference inks ST10–ST12, only ST10 had a greenish colour, while the reference inks ST11 and ST12 were silvery. Addi- tionally, the majority of the inks was at least a bit glittery under the microscope (6.3x–32x magnification). Most of the inks showed different degrees of losses of the ink layer after drying, which might be due to the binding agent not being strong enough. Furthermore, fine cracks in the ink layers could be observed on some inks. Inks which were produced using fine silver powder from grinding silver leaves with gum arabic by hand appeared finer under the microscope (6.3x–32x magnification) than those which were produced using silver refined by grinding in a mortar or amalgamation57 (Fig. 28). In particular, refer- 57 This goes along with observations made during the production of the reference inks which showed that inks which were prepared using silver powder obtained by manual grinding with gum arabic could be applied easier to the parchment samples with bamboo pens than those inks which were produced using silver powder obtained by grinding in a mortar or amalgamation. The finer silver powder mixed better with the binding agent resulting in better flowing inks. Fig. 27: The mounted samples of sub study 2 after accelerated ageing. In sub study 2 the sample set C was so deformed that the parchment pieces became detached from the mounting board. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0