The adhesion tester conforms to the latest industry standards and is designed to measure the strength of coating to a substrate. Adhesion testing is often associated with adhesives where bond strength measurement is critical for research and how well an adhesive bonds two materials. There are three different types of tests to measure the resistance, they are Knife test method, Tape test method and the pull off test method, all of which are destructive, so the test area needs to be repaired.See more.
In order for coatings to perform to a satisfactory standard, it’s important they adhere correctly to the substrates on which they are applied. There is a handful of well-known methods which can be used to establish how well a coating is secured to a substrate.
Most commonly a knife or a pull-off adhesion tester are measuring techniques used. The most important information to record when performing these test is if the bond failure was cohesive (A Failure within the coating film or at the substrate). Or Adhesive (Failure at the substrate / coating interface).
Knife Test Method
One of the simpler tests to perform requires a utility knife to pick at the coating. This method would give you a reasonable idea on whether the adhesion of a coating to a substrate is adequate. To measure the adhesion level you would look at two areas, the degree of effort involved to remove the coating for the substrate and also the size of coating removed.
Tape Test Method
When testing metal substrates, a more formal way to test is by using the tape test. The tape is pressure sensitive and once applied to a coating with pre-made cuts is removed. From this you can get a reading of the adhesion.
Pull-Off Test Method
The pull off test is a more quantitative adhesion test, a dolly or sub would be affixed using adhesion to the coating which is attached to a portable pull-off adhesion tester device. The load is applied increasingly to the surface of the coating until the dolly is finally pulled off. From this test you have a recording of the force which was required to pull the dolly of or force the dolly withstood, which will give you the tensile strength in psi or MPa.