On metal substrates a more formal version of the knife test is the tape test.
Powder coating tape test.
Essential that tape from the same batch be used when tests are to be run in different laboratories.
It s performed by cutting a crosshatched grid pattern into the coating all the way down to the substrate.
Note 4 permacel p99 tape previously identiļ¬ed as suitable for this purpose was withdrawn from manufacture in july 2009.
Apply any sticky tape then remove slowly.
The crosshatch test is designed to test the adhesion of the powder coating to the metal substrate.
8 3 for test panels report the substrate employed the type of coating the method of cure and the environmental conditions at the time of testing.
I usually test 2 3 surface areas on the specimen to determine an overall average.
If this is not possible the test method should be used only for ranking a series of test coatings.
5 chemical resistance test astm d1308 place approximately 10 drops of test solvent consisting of 95 by weight toluene and 5 by weight methal ethyl keytone on the surface of the coating.
No coating removal is a good pass.
An acceptable result will show only a little of the powder coming off from the grid cuts.
This test is easy and a must for checking powder coating adhesion.
Pressed down real good and then the tape is removed.
Pull the tape off aggressively and look at the tape and the part.
Results should be no lifting of the cured powder between scribe lines.
If a square or two of coating is removed adhesion can be.
That area is then judged to see if any paint was removed from the cross sections that were cut.
The test is performed by making a series of cuts through the coating.
The most common areas to test for basic powder coating functionality are.
The more paint that is removed the worse the overall grade would be.
There are two variants of this test.
Tapes and adhesion testing for powder coating.
The x cut tape test is primarily intended for use at job sites.
In its simplest version a piece of adhesive tape is pressed against the paint film and the resistance to and degree of film removal observed when the tape is pulled off.
Generally the pass fail is graded on a progressive scale.
8 4 if the adhesion strength of the tape has been determined in accordance with test methods d 1000 or d 3330 report the results with the adhesion rating s.
Allow to stand for 30 seconds.
A special pressure sensitive tape is then applied to the crosshatched area and then removed quickly at close to a 180 degree angle.
Last angle the tape at approximately 45 degrees then firmly holding the end of the tape give it a fast pull off the surface.
By far the most prevalent test for evaluating coating adhesion is the tape and peel test which has been used since the 1930 s.
