Is there a more quantitative method for determining the adhesion of a coating to a roofing substrate?
Yes. One easy method is to apply the roof coating to the prepared roof surface and while still wet, imbed a 1″ wide cloth strip. The strip should be ~12″ long, but imbed only about 6″ of the strip. Allow this to dry. If wet adhesion properties are needed, adhere a 12″ diameter by 2″ sheet metal cylinder to the roof substrate using a caulk. When the caulk is dry, fill the area with water and wait for one week. After the dry/immersion period, attach a small fish scale (the kind used by sport fisherman, available at sporting goods stores) to the free end of the cloth strip. CAREFULLY, cut the 1″ wide sides of the strip that is imbedded in the coating, being careful not to cut into the roof substrate. Pull slowly on the fish scale, pulling the 1″ wide cloth strip away from the roof substrate. Read the weight (force) required as the cloth strip is pulled away. This method is similar to the ASTM C-794 adhesion test.
