Rationale

Current Wording — ASTM E74-18, §6.1 “External surfaces of weights shall have a finish (Roughness Average or Ra) of 3.2 µm (125 µin.) or less as specified in ASME B46.1.” Proposed Wording — ASTM E74, §6.1 (third sentence, revised) “External surfaces of weights should have a maximum surface finish (Roughness Average or Ra) of 3.2 µm (125 µin.).” The 3.2 µm maximum in §6.1 functions as a design recommendation, not as a calibration acceptance criterion. ASME B46.1 specifies the measurement method, and the 3.2 µm value is itself a maximum, so the requirement is technically verifiable. The substantive issue is that the standard assigns no contribution from surface finish to the measurement uncertainty budget and provides no acceptance procedure linking surface finish to calibration validity. Auditors have cited laboratories for non-compliance against a requirement that the standard itself does not define how to verify. ISO 376 contains no equivalent requirement. In informal polling of peer laboratories, none have produced documented compliance records; several believed they were compliant but could not produce evidence on request. Changing the verb from shall to should aligns the requirement with its actual function as a recommended design criterion. The parenthetical “(125 µin.)” is retained as informational only, consistent with the SI-only convention of E74. Adding “maximum” before “surface finish” and removing the trailing “or less as specified in ASME B46.1” clause clarifies that 3.2 µm is the upper bound and avoids the construction in which the existing clause reads as imposing a measurement methodology that the standard does not otherwise define.