Stress risers are nicks,scratches.burrs,etc that a crack may develop from due to flexing [fatigue] of the aluminum structure. After precleaning with Alumiprep 33 or Metal Prep 79, rinse with water. Apply Alodine without dilution by brushing or immersion or swabbing with sponge. Rinse with water and surface is ready for paint. This is a visible coating which leaves the surface with a golden coloration.The alodized surface provides protection against weather and firmly bonds paint.ALODINE 1201 is a nonflammable, chromic acid based, coating chemical that will
produce a chrome conversion coating on aluminum and its alloys.
The coating formed by ALODINE 1201 is gold to tan in color and it becomes a
part of the aluminum surface. This chrome conversion coating offers the best
affordable substrate for both paint adhesion and corrosion resistance.If you use an etch primer it will remove the conversion coating. Just use an epoxy primer like Valspar VP50.If you do not want to do the pre-etching then use a etch primer directly on cleaned [metho] aluminum surface,but remember this will not have as good a long term resistance to corrosion .Cheer T87