copper alloys –brass, bronze…, iron alloys –steel, ferroalloys…, lead…
Authentication and evaluation of the antiquity using microanalysis, thermoluminescence, lead 210 measurement, X-Ray imaging
The scientific expertise of bronze or brass objects mainly consists on the study of a metal sample using scanning electron microscopy. The aim is to determine the composition of the alloy and the compatibility of the corrosion phenomena with the presumed antiquity of the cast.
Sometimes, the metal analysis can reveal a modern metallurgy (detection of aluminum e.g.).
In parallel, for alloys mainly containing lead, we can evaluate the antiquity of the metal fabrication by measuring the residual activity of a lead isotope so-called Pb 210. This measurement is used to confirm without any ambiguity if the metal used for the realization of the object is modern or not.
Whatever, there is no direct dating method for metal.
In addition to the metal analysis, for closed pieces, a thermoluminescence test can be performed in order to evaluate the age of the last heating of the casting core.
Finally, as for terracotta items, we propose to complement these approaches by an X-ray imaging in order to check the homogeneity of the piece from which a single micro-sample was previously analyzed.
Metal characterization and state of conservation using X-Ray imaging
For archaeological purpose or as a part of a preliminary diagnosis for restoration, the metal analysis is useful to provide information about the manufacturing processes and the corrosion state of the objects with the complementary X-Ray observation.
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