Seite - 192 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

192 Alteration study of silver inks on parchment results discussed so far, the preparation step of polishing does not seem to contribute to a further degradation of the collagen structure. When comparing the shrinkage temperatures of the two fibre samples of the Vienna Genesis (Table 5) a distinctive difference between the measured values is evident. The first sample (Vienna Genesis_S1), which was taken from folio 2, has a shrinkage temperature of 30.5 °C. A shrinkage temperature of 48.0 °C was measured for the second sample (Vienna Genesis_S2), which originated from folio 9. In accordance with the low shrinkage temper- ature of Vienna Genesis_S1 very little shrinkage activity could be observed, whereas in the case of Vienna Genesis_S2 three of the five shrinkage intervals – A1, C and A2 – could be documented. Further comparison of the shrinkage temperatures TS of the fibre samples of the Vienna Genesis and the reference samples after the artificial ageing, given in table 5, shows that the values are approximately at the same level and well comparable. Table 5: Mean values for the temperatures of the first observed shrinkage activity (Tfirst), the shrinkage temperatures (TS), the temperature at the end of the main shrinkage interval (TS, end), the length of the main shrinkage interval (ΔT), the temperature of the last observed shrinkage activity (Tlast) and the length of the entire shrinkage interval (ΔTcomplete) of the reference samples after 13 days of artificial ageing and the fibre samples of the Vienna Genesis. Sample Tfirst [°C] TS [°C] TS, end [°C] ΔT [°C] Tlast [°C] ΔTcomplete [°C] Vienna Genesis_S1 26,4 30,5 31,1 0,6 31,1 4,7 Vienna Genesis_S2 30,3 48,0 48,8 0,8 51,1 20,8 NP_p_13d 30,2 ± 0,6 33,3 ± 0,6 36,3 ± 0,7 3,0 41,3 ± 1,6 11,1 LP_p_13d 31,4 ± 0,9 34,9 ± 0,7 39,8 ± 0,9 4,9 44,2 ± 0,9 12,8 MP_p_13d 37,6 ± 1,0 40,7 ± 1,1 43,6 ± 0,8 2,9 52,0 ± 1,1 14,4 Fibre Morphology In addition to determining the shrinkage temperatures, the fibre morphologies were ana- lysed. The information gained should contribute to a more detailed characterisation of the condition of the different samples. The description of the fibre morphologies was carried out according to the IDAP guidelines64. The analysis was done directly before the analysis of the shrinkage temperatures at room temperature. Therefore, approximately ten well-sep- 64 Larsen, 2007. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0