Page - 230 - in The Vienna Genesis - Material analysis and conservation of a Late Antique illuminated manuscript on purple parchment

230 The miniatures of the Vienna Genesis: colour identification and painters’ palettes paint layers contain yellow ochres. Artist D used red and brown ochres to paint various shades of dark brown sometimes with the addition of red lead. Grey is a mixture of indigo, ultramarine blue, Egyptian blue and lead white. The feet of the sleeping Joseph were painted with this mixture on folio 15, page 29. In other grey areas, it seems that madder is added. A distinctive feature of painter D is the use of iron gall ink as black pigment. Cracks and cups disrupt the sometimes brownish paint layers. The iron ions of the ink have de- graded the parchment to the point of losses, a phenomenon known as iron gall ink cor- rosion19. In accordance, the XRF spectrum of measuring point MP16_12 on folio 16, page 32, reveals high iron (Fe) intensities (Fig. 34). Additionally, traces of manganese (Mn) as well as intensive signals of copper (Cu), arsenic (As), and lead (Pb) are present. While copper can be assigned to the analysed black area (iron gall ink), the peaks of arsenic and lead probably result from a green hue of the miniature painting on the other side of folio 16, page 31. A further comparison of the XRF spectra of the iron gall inks used by painter D (MP16_12) and painter A (MP2_3) (Fig. 34) shows significant differences regarding the elemental composition of the analysed materials. While the spectrum of the ink used by painter D shows a more intensive copper peak, no signals of the elements zinc or mercury are present. Therefore, the iron gall inks used by the two painters do not appear to be the same. The iron gall ink of painter D, which contains copper, has caused visible degrada- 19 Hofmann et al., 2007. Fig. 34: Comparison of the XRF spectra of the inks used on folio 2, page 3 (MP2_3, grey) and folio 16, page 32 (MP16_12, black). A spectrum of the parchment of folio 16 (MP16_3, purple) shows the background signal detected. Open-Access-Publikation im Sinne der CC-Lizenz BY 4.0