What is the allowed quantity of lead in dry surface paint when testing with XRF?

What is the allowed quantity of lead in dry surface paint when testing with XRF?

• A. 1.0 mg/cm2
• B. 10,000 ppm
• C. 0.5% = 5000 ppm
• D. 5000 ppm

Answer: (A)

XRF measurements are most reliable when the lead loading on the dry paint is kept within a specific surface amount. The limit for lead per area in this context is 1.0 mg of lead per square centimeter. Keeping within this loading ensures the XRF signal isn’t overly attenuated by a thick or highly pigmented layer, which keeps the reading accurate. If the coating exceeds this amount, the XRF result can become unreliable, and a destructive test or alternative method is typically used to determine lead content. The other options express lead as weight-based concentrations (ppm or percent), which depend on the paint’s thickness and density and don’t specify a fixed, area-based testing threshold for XRF.

XRF measurements are most reliable when the lead loading on the dry paint is kept within a specific surface amount. The limit for lead per area in this context is 1.0 mg of lead per square centimeter. Keeping within this loading ensures the XRF signal isn’t overly attenuated by a thick or highly pigmented layer, which keeps the reading accurate. If the coating exceeds this amount, the XRF result can become unreliable, and a destructive test or alternative method is typically used to determine lead content. The other options express lead as weight-based concentrations (ppm or percent), which depend on the paint’s thickness and density and don’t specify a fixed, area-based testing threshold for XRF.