What is a NIST Traceable PRD? Follow

Question: What is a NIST Traceable PRD?

Answer:

Many measurement methods specify that the instrument be standardized using a NIST Traceable PRD, or to BaSO4 or to PTFE. Does my HunterLab instrument comply? PRD is an acronym for Perfect Reflecting Diffuser. NIST considers pressed Barium Sulfate (BaSO4) and Polytetrafluoroethylene to be acceptable representations of a PRD and they have assigned values to the reflectance of pressed pucks made from these two materials. All current HunterLab Instrument Standard white tiles have calibrated values assigned to them that are traceable back to the NIST assigned PRD values.