Why Coatings Can Change XRF Results
XRF is a surface-sensitive technique. The analyser measures fluorescent X-rays from the material exposed to the beam, so a painted, plated, oxidised, galvanised, or coated surface may not represent the underlying material.
If the coating contains elements of interest, the analyser may detect those elements as part of the sample. If the coating sits above the target material, it can also absorb or reduce the signal from the substrate. This is especially important when testing light elements, thin layers, corrosion products, or materials where coating thickness is variable.
Some XRF applications are specifically designed to measure coatings or plated layers, but this requires the correct method, calibration, and knowledge of the layer structure. For general material identification or grade verification, the surface may need to be cleaned, prepared, or measured in a representative location to avoid misleading results.
Reviewing XRF for Coated Materials
For more detail on the measurement method, review PAS’s overview of X-Ray Fluorescence technology. To compare field-ready instruments, explore PAS’s handheld XRF analysers through Portable Analytical Solutions, or contact our team to discuss coated samples and testing requirements.