Seite - 80 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

80 Purple dyeing of parchment Three batches were prepared from Lasallia pustulata. Two of them resulted in a vibrant purple colour, while the third did not turn purple but stayed brownish. The batches were prepared on 19 July 2016, 03 November 2016 and 12 May 2017. Lasallia pustulata de- veloped the dye in about three weeks. The pH value of the undiluted dye was between 9.77 and 11.26. The pH value of the diluted dye was at 10.31. Application As there is not much surviving knowledge about the historical methods of dyeing parch- ment, two different methods of application were tried: 1. application with a tool like a brush and a cotton swab 2. immersion of the parchment into a dye bath A further method is the application with a cloth, soaked in dyestuff. Parchment is placed between two of those cloths and pressed82. This procedure seems to leave marks on 82 Denoël et al., 2018, p. 9. Fig. 3: The application of the dye with a brush gave uneven results: a) flesh side, b) hair side, c) flesh side, d) hair side. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0