1 Scope
This document specifies four methods for the determination of the hardness of vulcanized
or thermoplastic rubbers on flat surfaces (standard-hardness methods) and four methods
for the determination of the apparent hardness of curved surfaces (apparent-hardness methods). The hardness is expressed in international rubber hardness degrees ( IRHD ). The methods cover the hardness range from 10 IRHD to 100 IRHD .
These methods differ primarily in the diameter of the indenting ball and the magnitude
of the indenting force, these being chosen to suit the particular application. The
range of applicability of each method is indicated in Figure 1.
This document does not specify a method for the determination of hardness by a pocket
hardness meter, which is described in ISO 48‑5.
This document specifies the following four methods for the determination of standard hardness .
— Method N (normal test) is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD , but can also be used for hardnesses in the range 30 IRHD to 95 IRHD .
— Method H (high-hardness test) is appropriate for rubbers with a hardness in the range
85 IRHD to 100 IRHD .