ASTM D4541 Pull-Off Adhesion Test Panels

Test panels or substrates used in testing by ASTM D4541 (Pull-Off Strength of Coatings Using Portable Adhesion Testers). This test method involves gluing a loading fixture (also called a dolly or stud) to a coated test panel or substrate. After the glue cures, the test apparatus is attached to the loading fixture and applies force at a steady and gradually increasing rate. The test continues until the loading fixture separates from the coated substrate or the specified load value is reached.
 
ASTM D4541 doesn’t specify the size of the substrate panel. However, it does need to be large enough to run the adhesion test, it is preferred to avoid edges, and it should be large enough to run multiple tests (probably 3, although that isn’t a strict requirement). The diameter of the contact surface of the loading fixture varies by brand and type of test instrument. This can range from 10 to 50 mm. Furthermore, the substrate should be thick enough to resist deformation during testing. The ASTM ILS precision study was run using ¼-inch thick carbon steel.
 
Given these considerations, Metaspec recommends using ¼-inch or thicker test panels, in sizes such as 2" x 4", 3" x 6", or 6" x 6". These unpainted and uncoated test panels are available with as-rolled, polished, sanded, or other surface finishes.