Issue link: https://ppgrefinish-na.uberflip.com/i/1031702
The Keys to Durability Two key elements contribute to a clearcoat's durability: UV absorbers and film build. UV additives absorb damaging ultraviolet rays, much like sun blocker for your skin. However, UV protectants cannot do the job alone in ensuring durability. FILM BUILD IS CRITICAL Film build is equally important to ensure long-term durability of the finish. Too low of a film build can lead to premature film failure, dieback and overall poor appearance. Too high of a film build can lead to solvent pop, dieback, and even potential adhesion failure. A final film build in the range of 2-2.5 mils is most commonly recommended. Whether using a value or premium clearcoat, a film build below 2 mils will decrease durability. So before spraying any clearcoat on a job for the first time, it is recommended to measure film build on a test panel. This will help gauge how your application techniques affect final film thickness. Two coats should suffice in creating adequate film build if using a high-solids, premium clearcoat. Some value- priced clears may require three coats to achieve the same degree of protection. Knowing the film build is especially critical if the job will later be buffed. In other words, one cannot apply a film build of 2 mils, then buff off a half mil. The result will leave not enough UV absorbers or resin solids to block out the ultraviolet rays, thereby compromising durability. Causes of Common Defects SOLVENT POP This regretful defect occurs when the solvent gets trapped in the clearcoat and "pop" through the surface, creating tiny pinholes or pop marks. The cause can be due to many factors, such as using a solvent that's too fast for the operating conditions, incorrect flash time between coats, too much film build, or incorrect spray pressure. DIEBACK The loss of gloss or matting after application can be also due to many factors: too fast a solvent, improper film build, or lack of proper flash time. SAGS Usually occurring down a vertical surface, sags can be caused by application errors (too much at one time), or an incorrect mix ratio, whereby the solvent may not evaporate fast enough. Another cause is not allowing enough flash time between coats. ORANGE PEEL A clearcoat having the textured look of an orange peel can result when applying the clearcoat at too great a distance; when incorrect air pressure causes the fluid to not atomize correctly, or if the solvent is too fast that it evaporates before the clearcoat is allowed to flow properly.