EPDM.. (etheylene propolene dien monomer) in its black state is typically stable and has great esasicisty,, but to make it white, titanium dioxide and other fillers have to be added to the black material to make it white,,, the down side is it also weakens the EPDM, All white EPDM tears fairly easy and is no where as strong as black materials, since the 45 and 60 mil sheet is manufactured in a two layer process and vulcanized together,, it was a natural progression to laminate weaker white reflective epdm to a bottom layer of stronger black epdm, It was a fair idea and was popular for a short time until the PVC, TPO, EIP, CPVC materials gained popularity and were more cost effective,,
So EPDM is a choice but there are as good and better materials on the market at a more reasonable price plus they are white or off white and reinforced with a 10x10 polyster scrim
just thought I would throw a few leg wetting facts out there for ya ponderance and edification,,,
damn ,,, I got to start drinking better
chipper