Gold‐coating thickness determination on Ag, Cu, Fe, and Pb using a handheld X‐ray instrument

Abstract

Here, the X‐ray fluorescence technique is used to determine the thickness of a coating layer as well as to analyze the surface of objects. Four metals (Ag, Cu, Fe, Pb) were covered with increasing thicknesses of gold. The measurements were performed with a commercial handheld instrument, X‐SORT (Spectro). In double layers, the thickness of the covering layer was assessed by (a) the ratio between the most intense fluorescence lines of the covered element, (b) a cross‐ratio between two lines of the elements in the two layers, and (c) the ordinary partial least squares (PLS) regression method. In all cases, the curves obtained could be used for the quantitative determination of the thickness. The experimental data followed the theoretical trend even though the values of the attenuation parameters were not always in agreement with the theoretical ones. Comparisons and discussion of the results of the different approaches and also with models in the literature are made. The methods studied were applied to determine the nature of the coating layers of some gilded objects and proved to be suitable for estimating the thickness of gold by providing results that were in good agreement with each other.

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

“…The Fe isotope in magnetic particles and Au isotope in report probes were simultaneously and sensitively detected by the elemental mass spectrometry. 197 Au/ 57 Fe isotopic ratios and CEA concentrations showed good linearity in the range of 0.6-300 ng mL −1 , with a detection limit of 0.09 ng mL −1…”

“…Two papers have discussed the measurement of the thickness of organic layers on sterling silver 56 and the thickness of an actual gold layer on silver, copper, iron or lead . 57 In the paper by Porcinai and Heginbotham, organic layers of known thickness and of several commonly used protective coatings (Zapon nitrocellulose lacquer and the acrylic resins Paraloid B72 and Paraloid B44) were used as calibrants for the XRF analysis. 56 The method worked through the amount of fluorescence attenuated from the metal substrate below the organic layers.…”

“…Sabbarese et al used a handheld XRF instrument to determine the thickness of gold layers covering four metals. 57 This was achieved by first covering the metals with different thicknesses of gold so that a calibration curve could be established. This was accomplished in three ways: a ratio of the most intense lines of the covered element, a ratio of the intensity between two lines (one from each layer) and a partial least squares method.…”

Angle-Dependent XRF Analyses: Pros and Cons of a Novel Technique in the Field of Cultural Heritage

“…Indeed, though XRF averages out the composition of the whole volume investigated, different attempts have been made to retrieve the elemental distribution inside a multilayered sample. In particular, the ratio between different fluorescence lines (Kα/Kβ or Lα/Lβ intensities ratio) is often applied on metallic artifacts to measure the thickness of gildings [50][51][52][53][54][55][56] or the Monte Carlo simulations are used to create theoretical spectra of multi-layered samples, which are compared with the experimental data obtained on the unknown samples [57][58][59]; and finally, confocal micro XRF (CµXRF), employs capillaries to select a small volume of the sample to be analyzed, performing this task for more than twenty years [60][61][62][63][64][65].…”

Atomic spectrometry update – a review of advances in X-ray fluorescence spectrometry and its special applications

“…The estimation of the coating thickness of gilded objects using a commercial XRF spectrometer was studied by Sabbarese et al 107 using four metals (copper, iron, lead, silver) covered with increasing thicknesses of gold. For double layers, the thickness of the covering layer was assessed by (a) the ratio between the most intense fluorescence lines of the covered element, (b) a cross-ratio between two lines of the elements in the two layers and (c) the PLS regression method.…”