National Association of Hoisery Manufacturers (NAHM)

The Renfro Durometer was designed to measure the tension in a fabric while streched on NAHM sizing forms to accurately measure the maximum size of a sock. The durometer determines two functions. The first procedure answers the question of whether or not a sock will fit a given size form. The second procedure is used to determine the largest form the sock will fit, without refernce to it's specified size.

Sock Durometer Instructions

PTC Metrology is a NIST Traceable/ A2LA Accredited Laboratory for durometer calibration and meets the requirements of ISO/IEC 17025, ANSI/NCSL Z540-1, and ISO 9001 or 9002. Certification is available for any durometer type covered by current ASTM D2440, ASTM F1957, ISO 868, ISO 7619, or DIN 53505 standards.. The Calibration Report will include both "as received" and "as left" data on the force curve measurement (normally every 10 points over the durometer's scale from 10 to 100). Durometer calibration includes: indenter geometry and extension, indicator linearity from 0 to 100, and force curve. Other durometer types, custom models, and durometers of any manufacture can also be certified by PTC Metrology.