The tin mercury inlay of a cabinet manufactured by Hendrik van Soest: A case study

The tin inlay of a piece of furniture designed by Hendrik Van Soest has been investigated for its composition, microstructure and corrosion. Small samples were removed and investigated with optical microscopy, micro X-ray fluorescence spectroscopy, scanning electron microscopy with energy dispersive X-ray detection and synchrotron radiation X-ray diffraction. The results show that the inlay is composed of a binary alloy consisting of tin and mercury. The composition suggests the use of an amalgam to produce the metal inlay. However, the microstructure of the inlayed fillets proves that tin sheet was used instead of a tin mercury amalgam. Corrosion of the tin inlay is the most important sign of deterioration. Analyses show the presence of a thin layer of tin oxide chloride hydroxide in direct contact with the metal. This layer is covered by a layer of the more common tin corrosion compounds romarchite and cassiterite. The harmful effect of chloride containing compound is shown by the advanced corrosion. For future preservation of the tin inlay this compound must be either removed or be immobilized.