When epoxies are not post cured, they tend to go soft on the first application of heat. It is during this first heat cycle that the last portions of uncured resin cures and hardens off giving the resin its future heat resistance.  Hence why normally the post cure is done to ensure this happens under controlled conditions. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thank you Warren. 

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