Several reinforced plastic laminates that show promise of having good strength properties at elevated temperatures are being tested to determine their strength and elastic properties. This report, the fourth of the series, presents results of mechanical tests on an epoxy resin laminate reinforced with glass fabric Epon 1031 with 181-Volan A. Data were obtained after exposure periods from 2 minutes to 1,000 hours from such tests as weight loss, flexure, tension, compression, interlaminar shear, and bearing. Most of the tests were made parallel to the warp of the glass fabric to determine the effects of time and above-normal temperatures on the strength properties. Tension tests, however, were made at both 0 degrees and 45 degrees to the warp to obtain data from which edgewise shear strength and modulus of rigidity can be calculated. Creep and stress-rupture data were obtained under both tension and compression loads. In general, the strength properties of this epoxy glass fabric laminate decrease with increases in temperatre at constant periods of exposure. Specifically, however, the resin softens and the strength of the laminate decreases with the first application of heat, but then at constant temperature the strength properties often increase. Finally, after some critical time, additional exposure causes the properties to decrease. The specific magnitude of these strengths are presented in tables and curves. Author-PL.