Corrosion and adhesion. Shotblast vs no shotblast

Has anyone seen a technical analysis comparing paint adhesion/corrosion resistance on aluminum castings that have been "shotblasted and pretreated" vs "pretreated only?" The pretreat in question is borated cleaner, sulfuric acid de-ox, and yellow chromate". I have a customer questioning our ability to remove general oxides thru pretreatment only.

John,

I have not seen any reports on the subject; however, I can tell you that shot blasting will increase the amount of surface area of any material. That means that you are increasing the porosity of the material which translates into greater or normally better adhesion characteristics than chemical pretreatment only, especially on heavy viscous coating materials.