Effect of Profile Uniformity on Coating Performance

It is necessary to control the profile of abrasive-blasted metal surfaces to a degree. But it is not necessary to maintain an exact profile on all surfaces as long as the profile falls within an acceptable range. The acceptable range is usually determined by the type of coating and total dry film thickness (dft) being applied. Generally, the profile should be 20 percent to 25 percent of the total dft. For a typical thin-film coating applied at 5 to 7 mils (100 to 175 microns) dft, the acceptable surface profile range would be from 1 mil (25 microns) to 1.75 mils (44 microns). The deeper the profile, the more coating required to fill it and achieve the required dft. Inadequate surface profile jeopardizes the desired coating adhesion.