Use of analytical pyrolysis to characterize Egyptian painting layers

Summary

An Egyptian wooden sarcophagus and a cartonnage (664–525 B.C.) were subjected to pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS) and Fourier-transform infrared spectroscopy (FT-IR) in order to characterize pigments and organic binding media. The aim of these investigations is to acquire a better knowledge of the painting technique used in ancient Egypt. Results showed that PY-GC-MS offered a rapid tool to discriminate between wax-based- and animal protein-based binders and to recognize the use of mixtures of the two products. FT-IR corroborated the pyrolysis findings, but sometimes provided less unequivocal results than PY-GC-MS. As an additional benefit, PY-GC-MS allowed the identification of a yellow pigment as the arsenic sulphide orpiment by means of the volatile As₄ among the pyrolysis fragments.