Seite - 179 - 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 179 Table 2: Mean values for the temperatures of the first observed shrinkage activity (Tfirst), the shrink- age 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 (Tcomplete) of the following sam- ples: one fibre sample of the Vienna Genesis from folio 2r (Vienna Genesis_S1), an unaged sample of reference parchment of NP (NP_ref), a sample of reference parchment NP after 1 week with 30 °C, and alternating 30 %RH and 70 %RH (NP_30/30/70/1w), after 1 week with 80 °C, and alternating 30 %RH and 70 %RH (NP_80/30/70/1w), after 2 weeks with 80 °C, and alternating 30 %RH and 70 %RH (NP_80/30/70/2w), after 3 weeks with 80 °C, and alternating 30 %RH and 70 %RH (NP_80/30/70/3w), after 1 week with 95 °C, and alternating 30 %RH and 70 %RH, (NP_95/30/70/1w) and after 13 days with 95 °C, and alternating 30 %RH and 70 %RH (NP_95/30/70/13d) sample Tfirst [°C] TS [°C] TS, end [°C] ΔT [°C] Tlast [°C] ΔTcomplete [°C] Vienna Genesis_S1 26,6 28,4 29,4 1,0 30,5 3,9 NP_ref 53,0 ± 1,5 54,6 ± 1,3 56,9 ± 0,6 2,3 58,1 ± 1,0 5,1 NP_30/30/70/1w 52,2 ± 0,7 53,9 ± 0,7 55,6 ± 0,4 1,7 56,9 ± 1,0 4,6 NP_80/30/70/1w 41,0 ± 1,5 43,6 ± 0,8 45,5 ± 1,4 1,9 47,1 ± 1,3 6,1 NP_80/30/70/2w 38,8 ± 0,5 40,3 ± 0,3 42,6 ± 0,3 2,3 43,8 ± 0,5 5,0 NP_80/30/70/3w 34,1 ± 0,3 37,5 ± 0,5 40,2 ± 0,2 2,7 42,0 ± 0,6 8,0 NP_95/30/70/1w 30,4 ± 1,0 34,1 ± 1,5 36,6 ± 2,4 2,5 39,4 ± 3,6 9,0 NP_95/30/70/13d 25,8 ± 1,5 32,6 ± 1,3 37,1 ± 1,1 4,5 37,5 ± 2,8 11,7 Based on these first values the best-suited ageing conditions were developed step by step. Therefore, samples of the reference parchment NP were artificially aged for three weeks at a temperature of 30 °C and relative humidity of 30 % and 70 %, which were each held constant for 12 h. The artificial ageing was undertaken in a climate chamber56 VCC3 4034 (Vötsch Industrietechnik), which was controlled by the software SIMPAT 4.0. Since no changes of the shrinkage temperatures could be observed by the application of these conditions (Table 2), a second run was carried out using slightly different ageing conditions: while the parameters of relative humidity and duration were kept the same, the temperature in the climate chamber was increased to 80 °C. In the course of this run, sam- ples were taken weekly in order to determine the shrinkage temperature. As can be seen in Table 2, the most significant change of the shrinkage temperatures takes place after one week of artificial ageing. Hereby, a decrease of the shrinkage temperature starting at 54.6 ± 1.3 °C down to 43.6 ± 0.8 °C could be observed. Following this first drop of the shrinkage 56 The climate chamber was provided by the Institute of Art and Technology, University of Applied Arts Vienna. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0