The most common cause of incomplete curing is the use of inaccurate resin to hardener ratios and inadequate mixing of system components.  It is important to verify correct mix ratios on product containers before measuring and weighing resin, hardener and any fillers or pigments being used.  The scale used for weighing must also be accurate.  During mixing, resin, hardener and fillers should be stirred together for one to three minutes, checking the time on a clock.  Mixing container bottom and sidewalls should be scraped frequently to ensure that all components are fully incorporated.  Shop temperature should also be monitored.  The cure cycle of most materials is determined at temperatures between 75-77ºF.  Colder or warmer shop temperatures will affect the cure schedule of the polymer.