I believe a better solution is to use ceramic shot (Zirshot) in this application. Zirshot does not create any iron contamination on the surface so there is no need for chemical treatment. It has the capabilities of peening at relatively high intensities, (10-15A)is very possible. In addition, Zirshot provides a very consistent surface finish especially on aluminum. I encourage you to explore this product.

Regards,

Jeff Girman
Saint-Gobain Zirpro
[email protected]
Phone: (919) 593-4813