I just recently picked up my car shell from the media blaster today and on the way home I got caught in some light raindrops. It by no way was soaked but between the rain and humidity I can see surface rust already. The plan was to have it striped, brought home and cleaned of media, wiped down with degreaser and then primed with some DP40LF epoxy. I needed to do some sheet metal replacement even though the car is pretty solid and I wanted to get all the grease, grime, and undercoating off before doing so. Because this is going to be an ongoing process, I was led to believe that the epoxy was my best option in protecting the fresh metal till I could finish all the work. Now I need to remove the surface rust (flash rust) that has begun showing it’s ugly head. I have used a red scotch brite pad and it does take it off with a lot of effort. I have also used a 3M-scotch brite roloc disk and a conditioner disk, all of which works and probably would be doable albeit a slow process seeing as I have the whole shell inside and out to do. The problem is the areas that you are not going to be able to get those into. . I feel I will have to use some type of metal prep / wash to get all the areas converted. Maybe I can explain a little better, I had the shell thermally baked and then glass beaded. This removes everything and I do mean everything, no seam sealer bondo or even the lead at the quarter and roof joint. When I picked it up, the metal was as you would expect to see if it was lightly blasted, clean and slightly gray. Now for the most part the entire shell has taken on a light brown color, all in a day and a half. When you run your fingers over it, they turn brown. I am being told that any thing that is a type of acid prep will keep me from being able to use the epoxy primer I had planed on using (DP40LF). Picklex 20 or something similar has been suggested but was warned not to do so under the epoxy I was planning on using. I am also aware that you must wipe dry most of these converters so as not to leave an excessive amount of residue on the surface or you could have future adhesion problems. Someone recommended this stuff (www.zerorustusa.com/prepstep.php). It claims to be acid free so I am assuming it can be used under the epoxy that I have listed. Since I was also concerned about the other types of converters gathering in areas that I might not be able to wipe down or get at with out more than just an air hose, such as seems and inner panels, Zero Rust Prep Step looked to be a better fit, as it didn't list excess removal as a requirement. The shell is stored in an attached garage so it is reasonably protected but I didn’t want to run the risk of moisture getting under a typical primer and becoming a problem later on down the road. Am I right in thinking this? If I use an acid type of prep, is there another primer that might work for my purpose?