What does a XRF inconclusive classification mean?

• A. Lead is definitely above the standard.
• B. Lead is not present below the standard.
• C. The XRF cannot determine with reasonable certainty whether lead is present at or above the standard.
• D. The surface has been tested adequately.

Answer: (C)

XRF inconclusive means the instrument cannot determine with reasonable certainty whether lead is present at or above the standard. This happens when readings are near the device’s detection limit or when surface conditions—like multiple paint layers, varnish, moisture, or rough/irregular surfaces—create uncertainty in the measurement. Because of that uncertainty, you can’t classify the surface as above or below the lead standard based on the XRF alone. The correct move is to treat it as inconclusive and obtain a confirmatory laboratory analysis (such as a paint chip or bulk sample analyzed by a certified lab) to determine whether lead content actually meets or exceeds the standard.