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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]

  1. 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