Seite - 258 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

258 Conservation of the Vienna Genesis and the new storage system recto and verso. The most striking damages of the Vienna Genesis are the cracking and losses in the text area resulting from ink corrosion and degradation on every folio in varying de- grees (Fig. 21). This degradation ranges from 1 mm long cracks but no losses within a single letter up to large losses in entire sections of the text. The parchment appears to be very fragile on the edges of missing areas. Degradation of the parchment due to the silver ink corrosion is especially pronounced on folios 1, 13, 17, 18, 20, and 21. On folios with large losses, small flaps of parchment around an area of loss are folded over, like on the folios 18, 20, and 21 (Fig. 22). The folded flaps of parchment adhere firmly to the surface, which indicates that the thin parchment has been dried under pressure after humidification and flattening. A number of factors seem to have contributed to the severe degradation of the ink, see chapters on silver inks and on the alteration study. One of them is the significant copper content of the silver ink. The possible addition of compounds containing chlorine during the manufacture of the ink contributed to the formation of the main corrosion product sil- Fig. 18: The dark migration of the silver ink strongly interferes with the read- ability, folio 12, page 23. Fig. 19: Microscopic image, 12x magnifica- tion (scale bar 1 mm) of narrow dark halo around a letter, folio 12, page 23. Fig. 20: Shiny silvery halo, folio 9, page 17. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0