Page - 186 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

186 Alteration study of silver inks on parchment nitrate as an additional component. Therefore, the comparison of the visual appearance of the reference samples after ageing shows that the strongly pronounced ink corrosion resulted from the presence of potassium nitrate61 in ST4 and ST14, rather than from the refinement of silver using wine vinegar. Comparing the visual appearances of all reference inks of sub study 2 (ST10–ST14) regarding the used binding agent, it seems as if reference inks which particularly contained gum arabic developed more tension in the ink layer than those only mixed with water. For a direct comparison of the impact of the binding medium, ST11 and ST12 were prepared following the same recipe. ST11 contains water and ST12 contains gum arabic. It could be observed that ST11 was more powdery, while the ink layer of ST12 seems to be under tension (Fig. 34). 61 It is therefore assumed that the severe corrosion of reference ink ST3 results from the addition of sodium hydrogen carbonate. Fig. 33: Sample ST14_B after accelerated ageing. Fig. 34: Microscopic images, 12x magnification (scale bar 1 mm) of a) sample ST12_B, b) sample ST11_B. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0