X-ray fluorescence (XRF)
What is X-ray fluorescence?
X-ray fluorescence, usually abbreviated XRF, is a method for examining which elements are present in a material. X-rays are directed at a defined area, and the instrument measures characteristic radiation emitted by the material. Portable XRF instruments are used, among other applications, to analyze metals and heritage objects.
What can an XRF reading tell you?
A reading can provide information about the elements in the area examined. When no sample is taken, the examination can be non-destructive. XRF is not a hallmark, a maker identification or a complete authenticity test. A specialist must interpret the result alongside other evidence, such as fineness marks and the object's construction.
Limits of surface analysis
XRF examines the surface or a near-surface layer; it does not automatically analyze an entire object. Corrosion, silver plating or gilding may cause the measured surface to differ from the metal beneath it. The shape and condition of the test area also matter. On an irregular or composite object, one reading may not represent every component. A result alone should not be used to establish an alloy or fineness when the surface is not representative.
For plated wares such as EPNS, a surface reading must not be mistaken for an analysis of the core. The method, instrument settings and specialist interpretation affect what can safely be concluded.
References
- Canadian Conservation Institute: XRF spectrometry, including analysis of metals and heritage materials.
- Canadian Conservation Institute: Identifying Archaeological Metal, on surface analysis and why it may not show the composition of the underlying material.
