Master Bond EP121CL is a two component, high performance epoxy resin system featuring high thermal stability, superior electrical insulation properties and outstanding dimensional stability for casting, sealing, potting, encapsulation and impregnation for service up to 450-500°F. It cures readily at elevated temperatures to a tough strong solid with excellent long term durability and chemical resistance even when exposed to adverse environmental conditions. Adhesion to metals and other substrates is excellent. There is no cracking or separation of properly cured EP121CL resin from metal, etc., over a wide temperature range. Physical strength and electrical insulation properties of the cured EP121CL resin system are significantly superior to those exhibited by typical room temperature and also thermally cured epoxy resin systems. The cured epoxy can meet all service temperatures up to 500°F for limited time periods and 400°-450°F for prolonged exposures. It is also available in one component and thermally conductive versions. EP121CL has excellent optical clarity and can be used in optical and fiberoptic applications. The mixed compound (based on mixing 100 parts "A" to 80 parts "B" by weight) has a working life of 2-3 days at ambient temperatures.