An x-ray fluorescent analyzer (XRF) is a portable x-ray machine that is capable of reading through layers and layers of paint, and will detect any lead-based paint that could be lurking on your walls.

This form of testing is approved by the EPA, HUD, and the California Department of Public Health, and is used by Choice Property Services when testing for lead-based paint in your home. A surface-by-surface test is performed, with often over a hundred readings for one property.

Other ways to test for the presence of lead-based paint are either too invasive, or not accurate.

It is possible to have a state certified inspector assessor remove a 2 to 4 square inch sample of paint (usually with a chisel, making sure all layers are included) and send it to an NLLAP certified lab.  In order to certify a home to be free of lead-based paint, a sample must be taken of each painted surface in the home. The samples must be removed with lead-safe practices. This method is extremely invasive, and will leave the home with unsightly patches of missing paint, which are very difficult to repair.

Home test kits may not be used to certify a home or building in California, due to the inaccuracy of the tests. Not only do the tests not show when there is lead (a false negative result), but they also show lead-based paint is present when it is not (a false positive result.). For this reason, the EPA also does not recommend home tests.