Building a Clearcoat Foundation
Posted by Jay Schneider. Filed under Clearcoat.
July 31, 2009
The use of clear coats dates back as early as the fifties and sixties when automobile customizing was rampant with wild designs, colors and horsepower. The painter would simply lay down multiple coats, usually lacquer, of clear over the basecoat. This was done for depth of gloss, protection of graphics, murals or striping. With a thick layer of clear, one could buff the finish time after time to achieve that show room luxurious finish. The downside of heavy lacquer finishes was its cracking. After the solvent evaporated, the clear would shrink, crack, fracture and spider web.
Despite the failures of these early pioneering attempts, Chemical Engineers forged ahead - developing the clears we are familiar with on today’s automotive finishes. The benefits of today’s clearcoat technology may include but are not limited or related to ease of repair, appearance, environmental concerns, depth of gloss and cost savings.
Let’s discuss for a moment, building a foundation for a successful “Clearcoat Finish”. For our in-house testing, we choose 12 gauge thick steel panels, (once commonly used on vehicles). Common practices would include but not be limited to; 1) thoroughly cleaning the panel with phosphoric acid. This process 1) microscopically blossoms the steel surface exposing more surface and 2) cleans the finish by leaving an etched finish that will promote paint adhesion and be more likely to prevent peeling paint. Next step would include but not be limited to a conversion process where chromate or chromic acid is applied to the surface. This oxidizing application converts the steel finish to a more “NON-FERROUS” finish reducing the risks of rust. Once the finish is prepped, a self etching urethane primer is applied. This self etching primer, as its name applies, “Bites” into the chromated surface creating an excellent foundation for the urethane high build primer or basecoat/colorcoat to adhere to. High build urethane primers are designed for areas when small repairs must be made. These primers are excellent for hiding small imperfections where body fillers cannot be used. Their leveling capabilities, ease of application and sanding make them very popular in today’s body shop environments. Urethane primers are available in different base tones for hiding different paint colors and making a foundation that brings out the true color of the basecoat. Next up? Clearcoat types.
Scott S. Mc Lain
Sales & New Product Development