Seite - 94 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

94 Purple dyeing of parchment violet to blueish violet. Two pieces of parchment were hung in sunlight during oxidation, which results in a blue colour (Fig. 20). The colour achieved from the vat becomes in- creasingly blue the more it is used and the older it gets, until finally, only grey shades can be achieved. No differences in colour could be observed between the vat made from fresh glands and the one made from frozen glands. Results The experiments showed that it is possible to dye parchment with shellfish purple. The temperature of the vat has to be adjusted to a maximum of 25 °C. As in the case of orchil, the hair side absorbs more of the dye and turns out a little more saturated and darker than the flesh side (Fig. 21). Tissue remnants in the surface of the parchment also appear darker. The dyed parchments have an intense blueish-purple hue. The process of dyeing with shellfish purple is time-consuming and requires considerable experience and knowledge. In comparison, dyeing with orchil seems easier and less expensive. Fig. 21: Comparison of hair (above) and flesh side (below), parchment by Jiří Vnouček. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0