Seite - 180 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

180 Alteration study of silver inks on parchment temperature, a further decrease to 40.3 ± 0.3 °C after two weeks and to 37.5 ± 0.5 °C after three weeks of artificial ageing could be observed. In order to reduce the experimental time, the temperature was increased to 95 °C, while relative humidity was kept the same in a third run. A sample which was taken after one week showed a shrinkage temperature of 34.1 ± 1.5 °C. Since another determination of the shrinkage temperature after 13 days of artificial ageing showed only a smaller decrease to 32.6 ± 1.3 °C, which was comparable with the shrinkage temperature of the Vienna Gen- esis, the experimental run was stopped. Therefore, a temperature of 95 °C, a duration of 13 days and relative humidity of 30 % and 70 %, which were each held constant for 12 hours, were used for the ageing study. The visual appearance of the reference samples before and after accelerated ageing The visual appearance of all reference samples – inks and parchments respectively – was examined visually with the naked eye (Fig. 24-27) and under magnification before and af- ter accelerated ageing. A Wild stereo microscope M 400 (type 126269) at 6.3x–32x magni- fication was used to observe colour changes of the dyed parchment samples and their deformation behaviours as well as colour changes of the reference inks and the damage patterns of the inks. The following presents a compact overview of the information gained. Fig. 24: The mounted samples of sub study 1. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0