Tech Talk – Achieving Proper Adhesion for Roof Coating Applications

Adhesion tests are highly recommended to determine whether a roof is a candidate for restoration with a fluid-applied system.

American Weatherstar advises contractors to perform an adhesion test to help determine if a roof is a candidate for a roof coating application.

Eric Long, American Weatherstar Technical Services, demonstrates how to perform an adhesion test, and what materials are needed to perform a successful test. He includes helpful tips such as testing in multiple spots to ensure that time isn’t lost if the first test spot wasn’t fully cured.  Watch the video.

Contractors should start by thoroughly cleaning the test area, ideally with a power washer. If a power washer is not available, a Scotch Brite pad can be used to scrub the surface prior to rinsing. After the test area has completely dried, apply approximately 32 wet mils of coating on the clean, dry substrate.

In three separate areas, embed three cloth strips into the wet coating, leaving a few inches of uncoated fabric protruding. Apply enough coating to the topside to wet-out the fabric. The test areas should be allowed to cure for one to two weeks. The timeframe can be affected by climate conditions such as temperature and humidity.  If an early test fails, wait the full two weeks before checking other test areas.

To pass the test, there should be a minimum pull strength of two pounds. If little to no effort is required when peeling the fabric strip, it is doubtful that the chosen application is adhering properly. If lifting the fabric is difficult, or the fabric is separting from the new coating, odds are that there is acceptable adhesion. Contractors should consult with American WeatherStar’s technical department with test result.

Download a step-by-step instruction guide for adhesion testing.