Basic Adhesion Test for Roof Coating Applications

A key attribute for roof coatings is the bond achieved between the substrate and coating. National Coatings Corporation highly recommends test procedures outlined below be performed on roofs prior to the application of an AcryShield roof coating system. Running these tests will help ensure that the coating will adhere properly once installed.

CLEANING PROCEDURE

Need Help? Contact a Roofing  Professional  Zero Obligation Ideally, substrates need to be free of moisture, debris and contamination before the adhesion tests.  To test for cleanliness,  press a 3 to 4 inch long piece of 2 inch clear packing tape to the cleaned and dried roof using hand pressure. Then, peel the tape off the roof. If it comes off easily, and or is laden with dirt, degraded roofing material and other particulates, the roof is not cleaned satisfactorily. Re-clean and dry the roof and repeat this test. This test should be conducted in several areas around the roof, especially in ponded or other dirty areas.


Items Needed:

Roofing coating

Strip of fabric 12 inches long by 1 inch wide

Fish Scale (available at most sporting good stores)

12 inch diameter by 2 inch sheet metal cylinder (for wet adhesion)


 DRY ADHESION TEST

Apply the roof coating to the well prepared roof surface and while still wet, imbed a 1 inch wide cloth strip. The strip should be 12 inches long, but imbed only about 6 inches of it. Test areas should be allowed to cure to provide sufficient cohesion strength in coating (minimum 3 days to 7 days should be allowed to fully cure).  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 inch 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, in a smooth, peeling motion at an angle of about 45° to 90° with consistent force.  Read the weight (force) required as the cloth strip is pulled away. This method is similar to the ASTM C-794 adhesion test.

WET ADHESION TEST

Apply the roof coating to the well prepared roof surface and while still wet, imbed a 1 inch wide cloth strip. The strip should be 12 inches long, but imbed only about 6 inches of it. Allow this to dry.  Adhere a 12 inch diameter by 2 inch 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 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 inch 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, in a smooth, peeling motion at an angle of about 45° to 90° with consistent force.

For further information, please contact a National Coatings Technical Consultant.