Many manufacturers of sheet flashings, air/vapor barrier and waterproofing products report test results using test method ASTM D412. This is a misleading test, to say the least, for sheet membrane products.
ASTM D412 gives test results in PSI (pounds per square inch). While it is a useful test for characterizing solid rubber or elastomeric materials, sheet materials should use tests that measure PLI (pounds per inch). Here's why