Did quite a bit of research on the Sherwin Williams line of primers and after many conversations with government airframe mechanics and Sherwin Williams dealers I have come to the conclusion that even though the Product Data Sheets say you must apply primer over Wash primer, that is not always the case. As Van's states on their website for the quickbuild assembly, they use wash primer only for internal corrosion protection of their quickbuild components. While levels of protection vary, a chromated wash primer (the yellow ones) is excellent at corrosion protection and is flankly the only primer used on the inside of U.S. Army helicopters.
I have decided to go with the Sherwin Williams CM048646 Chromated Wash Primer on the internal components with no additional primer. Now on painted surfaces I will first apply the Wash Primer and then apply the CM0486707 Urethane primer before paint. Beware though on the chromated wash primer, the gallon can only comes with about 2.5 quarts of liquid because you then need to add either CM0110546 or CM0110646 as the hardener which comes as a complete gallon. It is a 2 to 3 mix ratio so it works out, but only produces a little over 1.5 gallons when buying a can of each.
Obviously opinions may vary, but I thought this to be an easy way of getting good corrosion protection without the Alodine process and buying fewer types of liquids for both the primer only areas and primer w/paint areas. Hope it helps somebody who is doing similar research and I look forward to reading the greatly varied opinions that are generally present in this section.
I have decided to go with the Sherwin Williams CM048646 Chromated Wash Primer on the internal components with no additional primer. Now on painted surfaces I will first apply the Wash Primer and then apply the CM0486707 Urethane primer before paint. Beware though on the chromated wash primer, the gallon can only comes with about 2.5 quarts of liquid because you then need to add either CM0110546 or CM0110646 as the hardener which comes as a complete gallon. It is a 2 to 3 mix ratio so it works out, but only produces a little over 1.5 gallons when buying a can of each.
Obviously opinions may vary, but I thought this to be an easy way of getting good corrosion protection without the Alodine process and buying fewer types of liquids for both the primer only areas and primer w/paint areas. Hope it helps somebody who is doing similar research and I look forward to reading the greatly varied opinions that are generally present in this section.
