BS ISO 3387:2020 pdf free.Rubber- Determination of crystallization effects by hardness measurements. BS ISO 3387 1 Scope This document specifies a test based on hardness measurements for determining the progressive stiffening of rubber with time, caused by crystallization. It is limited to materials having an initial hardness at a test temperature of from 10 IRHD to 85 IRHD. The method...