Master Bond Polymer System EP21 is a two component, room temperature curing epoxy adhesive featuring outstanding physical properties and a very forgiving 1 to 1 mix ratio by weight or volume. In fact, EP21 has the unusual characteristic of being able to adjust the properties of the cured system by altering the mix ratio. Adding more A part (e.g. 2:1 mix ratio) gives a more rigid cure while adding more B part (e.g. 1:2 mix ratio) gives a more forgiving cure. The EP21 produces high strength, durable bonds which hold up well to thermal cycling and resists many chemicals including water, oils, fuels, acids, bases and salts. It is serviceable over the wide temperature range of -60°F to +250°F. It bonds well to a variety of substrates including metals, glass, ceramics, wood, rubber, and many plastics. Once cured, EP21 is an excellent electrical insulator. This exceptionally versatile system is widely used in the electronic, electrical, computer, metalworking, appliance, automotive, chemical and OEM industries. The cured adhesive fully meets the requirements of MIL-A-81236 (OS) and MMM-A-187B among others. While the standard color of the cured material is gray, a wide variety of additional color choices are also available.