Per the (RMA) Rubber Manufacturer’s Association’s findings, heat and moisture seem to be the most common hazards which affect sheet rubber in the warehousing environment.  In addition, there are other special situations which can also cause deterioration, such as storage of rubber close to ozone producing electrical equipment (i.e. generators). 

Because of the many variables involved, it is impossible to guarantee rubber products for any specific period of time.  Our best time estimate is that there should be no appreciable change in physical properties for a six month period, and if stored in a favorable environment (cool & dry areas) at 70 Deg. F, preferably covered so that light, radiation, and humidity or vapors can not get to the material, should have a shelf life as listed below.