Have you ever placed a strip of tape, or for that matter, a few different kinds of tape strips in your arm to see if the adhesive was strong enough to pull the hair off. The tape tests for coatings which measure the adhesive strength of a coating to a substrate operates in the same manner. If a coating is to fulfill its function of protecting or decorating the substrate, it must adhere to it for the expected service life. This test method assesses the adhesion of coatings on metallic substrates (metal panel) by applying and removing pressure-sensitive tape over cuts made in the film. The test methods in question establish whether the adhesion of a coating to a substrate is at a generally adequate level. More sophisticated methods of measurement are required for higher levels of adhesion analysis.
A depiction of a crosshatch tape test on an applied coating to a metal panel is shown below. Notice, in this case, the many cuts in each direction on the film substrate. Some tape tests only desire cuts in a linear direction or in a figure X. The cuts are made to simulate the adhesion after scratches and other deformations have been made to coating. The tapes tested on the coating will be specific to the adhesion needed in a specific application. Please note at the bottom of the picture, in the area where the lines intersect, the tape is able to remove the coating from the panel thus causing adhesion to fail.
The procedure is repeated and in the report is noted the following:
1. Number of tests
2. Mean and Range
3. Failure point
4. Substrate employed
5. Adhesion tape rating
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