Desiccant for electrical and electronic devices

A method of desiccating a closure containing an electrical device comprising the steps of providing within an electrical device enclosure a desiccant consisting essentially of a dehydrating agent selected from particulate alkaline earth oxides having a particle size not greater than about 80 mesh in an amount of from about 5 to 80 percent by weight dispersed in an elastomeric matrix material having the property of retarding the rate of fluid absorption of alkaline earth oxides, the elastomeric material being selected from the group consisting of silicone potting and encapsulating materials containing recuring siloxane units, silicone RTV rubbers, vinyl plastisols, and polyurethane rubbers, the elastomeric matrix material having at the time of introduction of the alkaline earth oxides a viscosity of not greater than about 50,000 centipoises, and the alkaline earth oxides absorbing fluid within the device enclosure.