Adhesion is determined by pushing the coated panels beneath a rounded stylus or loop that is loaded in increasing amounts until the coating is removed from the substrate surface. Testing of paints generally falls into three categories.
Summary of test methods 3 1 test method a an x cut is made through the ﬁlm to the substrate pressure sensitive tape is applied over the cut and then removed and adhesion is assessed qualitatively on the 0 to 5 scale.
Paint adhesion test report. 1265 6 research project 0 1265 structural integrity of epoxy coated bars conducted for the texas department of transportation by the. In the paint and coating industries paint adhesion testing is often used to determine if the paint or coating will adhere properly to the substrates to which they are applied. This test is typically performed in a laboratory and is limited to testing on smooth flat panel surfaces.
There are several different tests to measure the resistance of paints and coatings from substrates. This test is completed by a tear test carried out using adhesive tape on the cross hatched part of the film the. Adhesion testing of epoxy coating by enrique vaca cortés miguel a.
3 2 test method b a lattice pattern with either six or. Carrasquillo research report no. Each aspect is examined in turn the results tabulated and the potential effect on a valid adhesion test result is discussed.
The cross cut test adhesion testing there are two variations of the cross cut test one is to simply cut an x into the paint film with a knife or razor and the other is more through and it calls for the cutting of a tic tac toe type of cross hatch grid into the paint film. The result of pull of adhesion testing is often critical to the acceptance or rejection of a coating process as the adhesion value quoted by the paint manufacturer can be adversely affected by aspects of the coating process. Normally after 30 days a second test should be performed.
As coatings continue to cure the adhesive properties will change. Cross cut test scrape adhesion pull off test and others. Paint testing can be done in a number of different ways.
Low adhesion values are indicative of premature failure of the coating in service and are often the result of inadequate. The test consists of making an incision in the paint film as far as the substrate using a cutting instrument to form a cross hatch then assessing the adhesion of the squares on the network formed. Introduction the tensile pull off method for adhesion testing as outlined in astm d 4541 and similarly in bs en iso 4624 involves gluing a test dolly to the coated surface and then pulling the dolly by.
Paint should be tested in a wet form for particular properties but also in the dry form. A device called a balanced beam scrape adhesion tester is used. Iso 2409 paint and varnishes cross cut test4 3.
The fact of the matter is that many industries use several different paint testing methods in order to ensure accurate results. Some coatings will improve in adhesion as the coating continues to cross link other coating systems decrease in adhesion due to different rates of shrinkage between substrate or coating layers within the system.