Your XRF Is Only as Good as the Surface You Measure

An XRF analyzer only analyzes the surface it “sees.” If that surface is plated, oxidized, painted, contaminated, or affected by casting segregation, the results may be misleading.
A small cordless rotary tool has become one of the most valuable accessories in my field kit. A few seconds of polishing often expose fresh metal and provide much more representative XRF results.
Of course, the preferred method is always to drill or machine the sample and analyze chips or freshly exposed bulk material. However, during field inspections, high-volume sorting, or when the customer does not want significant damage to the part, surface polishing is an excellent practical compromise.
Another advantage is when dealing with thick coatings. Measure the surface, polish, measure again, and repeat if necessary. Watching the XRF composition change after each polishing step often reveals whether you are analyzing a coating or the base metal underneath.
Remember: Never assume the surface represents the material beneath it. A few-second polish can prevent costly mistakes.