M. J. dos Anjos, J.T. de Assis, R. Cesareo, S. Ridolfi, R. T. Lopes, R. S. dos Santos, H. S. Gama Filho, D. F. Oliveira
Gilding Thickness Measurements Using EDXRF-Analysis
When a multi layered object such as a gilded material is analyzed by means of energy-dispersive Xray fluorescence (EDXRF), then one of the most serious problems consists in identifying for each element the correct layer, and in determining the thickness of the various layers, and particularly of the gilding. These questions can be solved, in many cases, by measuring the internal ratio of each element,i.e. the Kα/Kβ or Lα/Lβ–ratios of the various elements below the gilding (Cu, Ag, Pb) and of gold. In facto Kα/Kβ or Lα/Lβ – ratios are tabulated for infinitely thin samples; anomalous values for a given element may depend on the position and thickness of the layer in which the element is located,and on the thickness and composition of the superimposed layer. In this paper the ratios Kα/Kβ and Lα/Lβ are calculated in the case of gilded artifact as a function of material and thickness of the corresponding layer. Various examples are described: Gate to paradise on gilded bronze by Lorenzo Ghiberti in the baptistry of Florence; an inscription on gilded bronze on the top of the Trevi fountain in Rome; the carriage of king of Brazil Dom Pedro II on wood with superimposed a lead pigment and gilded.