ISO 7267-3:2017 specifies a method for the determination of the apparent hardness of vulcanized- or thermoplastic-rubber roller covers, expressed as the Pusey and Jones indentation value.
The Pusey and Jones plastometer apparatus is used to measure the depth of indentation of an indentor under a specified force into the surface of the rubber. The indentation value should not be confused with hardness as measured by the international rubber hardness test method ISO 48, since in this method the rubber immediately adjacent to the indentor is precompressed. The Pusey and Jones indentation value is an inverse measurement of hardness, i.e. the harder the rubber the lower the Pusey and Jones indentation value.