| esion testers are used to determine how well a | | | | His is a very simple test and requires a utility knife. To |
| coating bond to a substance or how well an adhesive | | | | determine if the adhesion of a coating to another |
| bonds two different substances. For engineering | | | | substance is adequate or not the knife is picked at the |
| requirements and demands coatings are becoming | | | | coating. The result or the performance of this test |
| very popular. For coating to function properly it is | | | | depends on eth degree of difficulty to remove the |
| important that the adhesive sticks to the substance | | | | coating and the size of the removed coating. Both |
| properly. Coating is generally used for high engineering | | | | these degrees are taken into consideration to |
| use and there are a number of methods through | | | | determine the test results. |
| which we can determine as to how well has coating | | | | With the help of a knife and a cutting guide two cuts |
| bonded to a substance. | | | | are made on the coating surface. At an angle called |
| Some of the well recognized methods for adhesion | | | | the vertex the point of knife is used to lift up the |
| testers are knife test, tape test and pull off tests. After | | | | coating from the material. This is a very subjective test |
| a test is performed it is important to record if the test | | | | and the value or result depends on the person |
| failed with the adhesive or the coating. Pull off test is | | | | performing it. A coating with a high degree of cohesive |
| the most commonly used test. It is a quantitative test | | | | strength may appear to have worse adhesion. |
| where a loading fixture known as a stub is fixed by an | | | | The third kind of test is the tape test. This is performed |
| adhesive to a coating. By using a pull off adhesion | | | | when pressure sensitive tapes are applied and |
| tester pressure is applied t the surface until the stub is | | | | removed over cuts of the coating. There are two |
| pulled off. The force applied to pull of the stub or the | | | | variants in this test: X cut tape test and cross hatch |
| force with which the stub withstood the pressure | | | | tape test. The former one is used at job sites and the |
| determines the test. | | | | latter one is used in laboratories on coating less than 5 |
| The strength is counted in pounds per square inch. The | | | | mils. |
| test fails only at the weakest point. This is the most | | | | These different adhesion testers are performed so |
| widely used test for determining the bond. In this | | | | that we can determine the bond between two |
| method the pressure applied is the maximum than | | | | substances or between a coating and a substance. All |
| compared to other tests. Therefore most prefer to | | | | these tests are very important for an |
| use this test. Adhesion testers function on mechanical, | | | | engineer’s point of view and only after the test |
| hydraulic or pneumatic pressure. | | | | succeeds can they be used for any activity or |
| The knife test is another method for adhesion testers. | | | | purpose. |