There are two categories of quality tests that can be performed on Teflon™ coatings after they have been applied. The first category we call “Basic Quality Tests,” which we covered in the January 18th blog post. The basic quality test category includes Visual Inspection, Finger/Coin Test, Holiday/Spark Test, and Dry Film Thickness Test.
The second category of quality tests for industrial coatings includes more advanced tests that require specialty equipment. These quality assurance tests can measure the quality of the bond of the coating to the substrate, the quality of the gloss finish, and the accuracy of your final color. And, you can increase the quality consistency by testing the viscosity of your coatings and confirming that your oven is calibrated and operating correctly.
This test provides an instant assessment of the quality of the bond to the substrate either in your shop, your lab, or in the field. Cross-hatch gauges are ideal for thin, thick, or tough coatings on all surfaces. The critical measurement is the amount of pressure (in PSI) required to detach the coating from the substrate. This test is often used to comply with the ASTM D3359-02 standard.
Digital gloss meters use an infrared source that emits a beam of light at an angle to the surface, and a sensor measures the reflected light. The standard test is usually a 60-degree light beam angle, and high-gloss surfaces are measured with a 20-degree angle. Advanced color testers can differentiate between over 16,000,000 colors. They are portable devices that can also include gloss testing in a single tester.
The correct viscosity of Teflon coatings is a critical element to make sure that the coating is fresh and properly mixed. Viscosity testers are either glass tubes or stainless steel cups. The glass tube models measure the time a stainless steel ball takes to drop through the liquid. The cup viscosity testers have a hole in the bottom that the coating passes through. The viscosity measurement is calculated from the time it takes before the first break in the liquid stream.
To make sure that you are baking your Teflon to the correct temperature, you should make sure your oven is calibrated correctly. And to prove your oven is operating correctly, you can also use an oven data logger.
Teflon coating systems only perform properly when all the specified processes are followed to a “T.” To make sure your industrial coatings will perform in the field, keep quality assurance testing equipment close at hand.