Fig. 4

FTIR spectra acquired from sample S3, i.e. a scraping of purple paint from the sky of plate 48 (improved positive). Materials identified in the spectra include calcite (1418, 875, 714 cm⁻¹), protein (3084, 2956, 2936, 2876, 1646, 1541, 1451, 1411, 1336, 1240, 1205, 1163, 1083, 1035 cm⁻¹), and polysaccharide (3377, 2927, 2851, 1603, 1418, 1152, 1082, 1027 cm⁻¹)