Springer et al. (1980) studied the effects of several environmental conditions, such as humid air at 50 and 100% relative humidity, saturated salt water, No. 2 diesel fuel, lubricating oil, anti-freeze and gasoline, on the tensile strengths of SMC-R25 and SMC-R50 composites. For the SMC-R25, the matrix material was a polyester, but for the SMC-R50, both polyester and vinyl ester resins