Lead-tin mirror formation from mixtures of red lead and tin sulphide.

Department of Chemical and Forensic Sciences, University of Bradford, Bradford, West Yorkshire BD7 1DP, UK.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy (Impact Factor: 1.98). 09/2003; 59(10):2291-9. DOI: 10.1016/S1386-1425(03)00072-6
Source: PubMed

ABSTRACT Mosaic gold, tin (IV) sulphide, is a yellow pigment which was known in antiquity but whose use was superseded by other more easily obtainable yellow pigments by the Renaissance.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.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Raman spectra have been obtained from a Madonna and Child tondo painting, known as the de Brécy Tondo. Despite the provision of only a small number of microscopic samples, definitive spectra were obtained from mineral pigments. From one specimen, spectra of an organic binder enabled the consideration of several possibilities to be accomplished and a suggestion proposed for the medium. In another specimen the identification of the spectral signatures of Prussian blue, which was only synthesised some 200 years after the predicated date of execution of the painting, indicated that some unrecorded restoration had been undertaken later in the painting's history. Research carried out on this tondo from 1987 to 1991 indicated the probability that it is the work of Raphael, a conclusion supported by further research recently undertaken on the provenance. The stylistic similarity of the tondo to Raphael's Sistine Madonna is very clear; the pigments identified in this analysis are consistent with a Renaissance attribution for the de Brécy Tondo.
    Analytical and Bioanalytical Chemistry 03/2007; 387(3):837-46. · 3.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Raman spectroscopic analysis of several stone samples with applied red pigments obtained from an archaeological excavation of an Augustinian friary discovered during the construction of an extension to Hull Magistrates Court in 1994 has revealed a surprising diversity of composition. Cinnabar, red lead and haematite have all been identified alone or in admixture; the cinnabar is exceptional in that it has only been found heavily adulterated with red ochre and red lead, as the other two pigments are found alone. There are signatures of limewash putty, which has been applied to the stone substrate prior to the painting, which is characteristic of the Roman method of wall painting, and there are no traces of gypsum found in the specimens studied. This evidence indicates an early mediaeval method of stone decoration.
    Analytical and Bioanalytical Chemistry 03/2010; 397(7):2685-91. · 3.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Even though kept in cultural institutions, artefacts can besubjected to accelerated deterioration due to high concentrationof pollutants in closed spaces. Potentially harmfulconditions have been evaluated by electrochemical reductionof corrosion products formed on metallic couponswhich have been exposed in selected places. In the case ofsilver coupons, this technique allowed chemical identificationof the tarnish layer (sulphides and chlorides), as wellas determination of the amount in which they are presenton individual coupons. Extension of this approach to leadraises some difficulty as identification of the reductionpeaks is more complex. In this work we combined electrochemicalreduction of corrosion products with in-situRaman spectroscopy to unambiguously correlate the reductionpeaks with the compounds present on the surface ofcoupons previously exposed in different French institutions.Raman analysis carried out prior to the electrochemicalreduction in a sodium sesquicarbonate solutionrevealed that the corrosion layer contains lead oxides,hydroxycarbonates and carbonates and in some cases formatesand acetates.
    E-Preservation Science. 01/2009;