XRF analysis is a non-destructive analytical technique that does not require sample removal. A reading is taken from the surface of the sample/sample site. The sample material is irradiated with electrons resulting in the emission of x-rays characteristic to the elements present. The energy emissions are translated into spectral peaks of varying intensity, resulting in a spectrum profile, which identifies the different inorganic elements present in the sample (i.e. lead, iron, copper, zinc etc.).
As XRF analysis takes a broad reading from the surface, the results present an overall reading from the area sampled, and considers all layers of the sample site (if multiple layers present/in-tact). The analysis is not quantitative. The X-ray intensity (size of spectrum peaks) is directly proportional to the concentration of the elements in the sample. While the results give a good indication of the elements present, in order to characterise individual paint layers or further confirm XRF results, elemental analysis using SEM-EDS would need to be undertaken.
The results are interpreted and presented in a report, with the XRF spectra included (example below):
Image: XRF Spectra, with zinc and barium predominate in the sample, traces of calcium, iron, cobalt, lead and strontium