Rust/POR 15/ Bondo Questions

[g-money]

I have some sheet metal that has some minor rust pitting and I want to fix it permanently. I will remove all the rust by grinding it out but why question is do I put POR 15 on then bondo over that or do I put Bondo on first then POR15 over the bondo. Just looking for the order to do things.
Thanks.
Galen

 

[American Pride]

por 15 would be first, then the bondo. prep the metal acordingly for the por, and sand the final product to take the bondo.