1 Scope
This document specifies a method for the determination of the apparent hardness, expressed in International Rubber Hardness Degrees (IRHD), of vulcanized- or thermoplastic-rubber roller covers. The method is similar in principle to the methods used for the determination of the hardness of rubber in ISO 48 in that it consists essentially of measuring the depth of penetration of a spherical indentor operating under a specified force. The apparatus used is similar to that described in ISO 48, having a base specifically designed for application to roller covers and similar curved surfaces.
NOTE With some rollers, there can be significant variation in the thickness of the rubber over the surface of the roller, which could affect the measured apparent hardness.