Minor Rust Repair - Part 3
Posted by Jay Schneider. Filed under Automotive.
July 1, 2010
Once all of the rust is removed and the surrounding surface scuffed, it is a good idea to acid etch the area using Phosphoric Acid, see figure 4. Phosphoric Acid should be available at your local auto paint supplier. The phosphoric acid is a deep cleaning action that microscopically “eats” away at the steel surface leaving a rough, clean and blossomed finish to where the primer has not only more surface to “bite” into but also maximizes the adhesion of the primer. Following the acid wash, the next most favorable step is the convert the clean steel surface using Chromic Acid, see figure 5. Chromic Acid is a powerful oxidizing agent that microscopically leaves a conversion coating that converts the exposed steel surface to a surface that is more resistant to corrosion.
At this point in the process, we have removed all of the rust and converted the surface to a more corrosion resistant one. We are safe to leave the area for a while knowing our surface is more resistant to corrosion.
It is time to determine what primer system you wish to use to prime the surface. The primer system used in this instructive blog is DuPont Vari-Prime and DuPont 4 to 1 mix Primer Surfacer. An excellent self etching urethane primer in its own right, Vari-Prime is a superb base primer with an excellent “surface bite” which maximizes surface adhesion and lays a foundation down for your Primer Surfacer. DuPont’s 4 to 1 Primer Surfacer, that is 4 parts paint to 1 part catalyst, when applied properly will provide a uniform surface which fills in and hides any rough, unfeathered paint layers or blemishes left on the surface – and when applied in multiple layers it is kind of like a spray on Bondo!
Next up – applying the primers…….
Scott S. Mc Lain
Lake Country Mfg