for everyones fyi
I found this brief history of epdm on
http://www.watergardencreations.com/pondpage.html
page. Forgive them for their numerous spilling oops spelling errors. Someone doesn't know about spell check.
EPDM Rubber Pond Liners****Why they are the BEST value for your money
EPDM, Ethylene Polymer Diene Monomer, is the very best liner membrane in the pond industry today, and has been since it's development in the 1950's. In a short history of this product, the US government engaged the services of Dow Chemical and Dupont in the mid 1950's to develop a waterproof liner material for holding water in the hot and sandy areas of the Mideast. This request was to obtain a waterproof liner that would hold potable water, and that could withstand high tempretures, be resilient to UV degradation and have ease of installation with little or no service requirments. After much research and testing, they came up with a sheet membrane of EPDM that met or exceeded every criteria of the US government. After this initial release of the product, independant companies secured rights to further develop and improve upon this product. By the end of the decade, with additional improvements and advancements of the EPDM membrane, it was found to be usable in many types of installations requiring waterproofing and containment situations.
EPDM is extremely flexible, much like a tire intertube, and extremely strong. EPDM has over 350% elongation, and it's performance characteristics are stable in tempreture ranges from -50 to 240 degrees before failure. The EPDM membrane also exhibits over 1,300 lbs psi tensile strenght, and 150 psi tear strenght. Though there are other types of membrane material in the marketplace today being sold as pond liner, none of them meet all the positive characteristics, ease of handling, and price of EPDM.
Both PVC, poly vinyl chloride, HDPE, high density polyethylene, are used as pond liner materials, but neither can withstand long term exposure to ultra violet radiation. Both products will deterioate and fail if exposed to direct sunlight for extended periods. There are other composite membranes that have been introduced into the pond liner marketplace in the past few years, like UltraGuard 20 Mil Polyomer, and Xavan. These products have neither the flexibility or ease of repair as EPDM rubber liner. None of these liners meet or exceed the EPDM membrane performance specifications, a liner which has been around for almost 50 years. We have incuded a copy of the spec sheet from one of the EPDM liner manufactures for your information.