There are two categories of Quality Tests that can be performed on Teflon™ coatings after they have been applied. The first category we’ll call "Basic Quality Tests," which are four straightforward tests to gauge the quality of the coating application. Every industrial coating shop should have equipment on hand to perform these basic tests.
The second category includes more "Advanced Quality Tests" that require specialty equipment, such as the Cross-Hatch Tape Adhesion Test. We cover these advanced quality tests in more detail in a post published on March 12, 2019.
The four Basic Quality Tests for high-temp coatings like Teflon are Visual Inspection, Finger/Coin Test, Holiday/Spark Test, and Dry Film Thickness Test.
A Visual Inspection is just what it sounds like—a thorough inspection for any defect in the coating with your eyes. For a more thorough inspection, use a high-illumination flashlight, magnifier, or microscope.
The Finger or Coin Test confirms proper intercoat and substrate adhesion. After the curing process of the topcoat is complete, run your fingernail or a nickel over the coating with moderate force to check if the topcoat will peel. Another version of this test is performed after coated panels are immersed in boiling water for 15 minutes.
To test porosity and flammability, use the Holiday/Spark Test. This is a dry film porosity test that utilizes an electronic transmission to identify the presence of a porous film. Any positive result received during the test indicates porosity in the coating.
The Dry Film Thickness Test uses an instrument to precisely measure the dried thickness of the coating system. A high-quality thickness gauge provides accurate readings with great repeatability to ensure coatings are applied within the required specifications.