My '51 1/2 ton stays outside and covered with a tarp to keep the rain off. I am in the process of sanding down my my cab. A few days ago I sprayed the top with Rustoleum Rust Converter to keep it from rusting over. It turned black and I assume that is doing its job of preventing rust from coming back. Is there anything special I have to do to the surface other than maybe using a prep to clean before I apply a 2 k primer? Wasn't sure if the two would be compatible.

Thanks,

JB