Can you paint directly over self etching primer?
Herein, should I sand self etching primer before painting?
You need to use self-etching primer to paint aluminum, but prep work is especially important. You have to sand the aluminum first, with 120-grit sandpaper. Follow up by wiping it down with mineral spirits. If you don't prep the aluminum well, the primer scratches off rather easily.
Considering this, how long should self etching primer dry before painting?
For best adhesion, apply 2 or 3 thin coats and allow each coat to dry for 2 minutes before applying the next coat. Allow the final coat of Self Etching Primer to dry for a minimum of 3-4 hours before dry sanding, or 15 minutes before wet sanding with #400 grit sandpaper. Do not use near open flame.
As a matter of FACT body filler works better when applied over a protective primer (epoxy or self etching) simply because the primer helps protect the bare steel from moisture. Body filler is extremely porous and will absorb moisture just from the air.