Accelerated Life Testing
Salt Spray Testing
Heat Treatment Studies
Paint & Coatings
ASTM D4147 is a standard method for application of film coatings of uniform thickness on a flat panel using the wire-wound drawdown bar.
A flat panel is secured on a firm horizontal surface. An ample amount of coating is poured across one end of the panel and the drawdown bar placed behind the coating. The bar is then drawn uniformly along the length of the panel toward the operator to apply a uniform film. The dry film thickness obtained is dependent on the combination of the bar used, the volume solids of the coating, and the speed of the drawdown motion.
This practice is useful in the laboratory to simulate roll-coated films.
Other methods are available at Touchstone which produce free films coatings that can be removed from the substrate and easily removed for testing.