Derek Broughton wrote:

Millimeters? Not "mils"? Liners in N. America are generally
measured in mils, and a 75 mil liner is thick. If it's really .75
mm, that's 30 mils, and I'd say too thin for an EPDM or vinyl liner,
but not HDPE and _perhaps_ not Butyl. Either way, butyl is a lot
heavier than any of the alternatives at the same thickness. If it
isn't heavier, it isn't butyl.

My 0.75 millimetre butyl liner......
http://www.bradshawsdirect.co.uk/Bra...oduct/GLBU.htm

QED ?
--
Pete C
London UK