Lead-tin mirror formation from mixtures of red lead and tin sulphide.
Mosaic gold, tin (IV) sulphide, is a yellow pigment which was known in antiquity but whose use was superseded by other more easily obtainable yellow pigments by the Renaissance. The identification of mosaic gold residues in a burnished golden mirror decoration on a XIIIth Century Spanish polychrome statue is important in that the first reference to the use of mosaic gold in the European literature dates from the XIVth Century, although the use of this material in China had been recorded some time before. In this paper, Raman spectroscopy, XRD and SEM are used in the analysis of the conditions required for the formation of golden mirrors using tin (IV) sulphide in admixture with dilead (II) lead (IV) tetroxide and mercury (II) sulphide. From these results, it is proposed that the major reactions are the reduction of Sn(IV) to Sn(0) with the accompanying oxidation of lead (II) oxide to lead (IV) oxide and the formation of lead (0) and lead (II) sulphide. From these results it was possible to explain the process of creation of the golden mirror from mosaic gold in the XIIIth Century.
Edwards
Howell G M
HG
Department of Chemical and Forensic Sciences, University of Bradford, Bradford, West Yorkshire BD7 1DP, UK. h.g.m.edwards@bradford.ac.uk
Dixon
Emma L
EL
Scowen
Ian J
IJ
Perez
Fernando Rull
FR
D007854:Lead / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D013054:Spectrophotometry, Atomic; D013059:Spectrum Analysis, Raman; D013440:Sulfides / Q000737:chemistry*; D014001:Tin / Q000737:chemistry*; D017971:Tin Compounds / Q000737:chemistry*; D014961:X-Ray Diffraction
D013440:Sulfides; D017971:Tin Compounds; C078041:tin sulfide; D007854:Lead; D014001:Tin; C028356:lead tetroxide