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Table 2 Composition of the W&N AOC tube paints used

From: The influence of light and relative humidity on the formation of epsomite in cadmium yellow and French ultramarine modern oil paints

Tube paint SEM EDX ATR-FTIR (see Figs. 2a, 7a)
Absorption bands (cm−1) Assignment
Cadmium yellow C, O, Cd, S, Al, Mg, Zn 3400 [–OH stretch]; 2924, 2854 [CH stretch], 1740 [ester carbonyl], 1379 [CH3 umbrella mode] 1244 [C–O ester]; 1160 [C–O ester], 1100 [C–O ester], 722 [CH2 rock] Oil
3649 [Mg(OH)2; O–H vibration]; 1484, 1421; [CO32−/HCO3; v3 asymmetric stretching vibration] 884 [v2 carbonate], 853 [v2 carbonate] 800 [CO32− bending vibrations] Hydromagnesite
Broad band at 3400, 1624, 980 Possible alumina hydrate (hydrated oxide of aluminium)?
French ultramarine C, O, K, Na, Mg, Al, Si, S 3340 [–OH stretch]; 2927, 2853 [CH stretch]; 1740 [ester carbonyl]; 1162 [C–O ester]; 1095 [C–O ester] Oil
3649, [Mg(OH)2; O–H vibration]; 3515, 3448, 1483, 1420 [CO3 2−/HCO3 v3 asymmetric stretching vibration]; 884 [v2 carbonate]; 854 [v2 carbonate] 800 [CO32− bending vibrations] Hydromagnesite
~ 1006 (Si–O–Si asymmetric stretch); 692, 657 (Si–O vibrations) Ultramarine
3692 [Al≡O–H stretch], 3619 [OH stretch]; 1027 [Si–O–Si]; 1006 [Si–O–Si], 913 [Al–O–H], 692 Probable kaolinite (an aluminosilicate)
Broad band at ~ 3400 (–OH stretch), 1624 broad band Possible alumina hydrate (hydrated oxide of aluminium)?