Neural network-based classification of X-ray fluorescence spectra of artists’ pigments: an approach leveraging a synthetic dataset created using the fundamental parameters method

Jones, Cerys; Daly, Nathan S.; Higgitt, Catherine; Rodrigues, Miguel R. D.

doi:10.1186/s40494-022-00716-3

Heritage Science

Table 1 Summary of pigment classes and data used to generate synthetic spectra

From: Neural network-based classification of X-ray fluorescence spectra of artists’ pigments: an approach leveraging a synthetic dataset created using the fundamental parameters method

Pigment class	Description of data	References
Arsenic sulphides	Average of theoretical orpiment (As₂S₃) and realgar (As₄S₄)	[27]
Bone black	Average of values reported for bone black (1:18 Mg:Ca) and ivory black (1:8 Mg:Ca) from SEM–EDX measurements	[28]
Chalk	Theoretical calcite (CaCO₃)	[27]
Copper pigments	Average of theoretical azurite (2CuCO₃·Cu(OH)₂), malachite (CuCO₃·Cu(OH)₂) and verdigris (Cu(CH₃COO)₂Cu(OH)₂·5H₂O)	[27]
Gold	Average of values for gilding on 14–15th century German and Swiss polychrome wooden sculptures from SEM–EDX measurements	[29]
Green earth	Average of values for Bohemian, Cypriot and Italian green earth pigment powders from SEM–EDX measurements	[30]
Gypsum	Theoretical gypsum (CaSO₄•2H₂O)	[27]
Iron earth pigments	Average of values for iron earth pigment powders sourced across Europe from SEM–EDX and quantitative XRD measurements	[31, 32]
Lead–tin yellow	Average of values reported for lead–tin yellow types I and II in 14–15th century Italian paintings from SEM–EDX measurements	[33]
Lead pigments	Average of theoretical red lead (Pb₃O₄) and average hydrocerussite (Pb₃(CO₃)₂(OH)₂)/cerussite (PbCO₃) content of lead white in 14–16th century European paintings from synchrotron XRD measurements	[34]
Naples yellow	Theoretical Naples yellow (Pb₂Sb₂O₇)	[27]
Smalt	Average of values for smalt in sixteenth century Netherlandish and French paintings from SEM–EDX measurements	[35]
Ultramarine	Average of values for lapis lazuli in 14–18th century European paintings from SEM–EDX measurements	[36]
Umber	Average of values for umber pigment powders sourced across Europe from SEM–EDX measurements	[32]
Vermilion	Theoretical vermilion (HgS)	[27]

Pigment classes in italics use the theoretical formulas listed to generate synthetic spectra. See Table 2 for quantitative values for all pigment classes, sourced from the references listed

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