I wet sanded a fuel tank and broke through the paint in a couple of areas and got down the bare steel. Those areas started to rust almost immediately.

Since I won't be able to prime the tank until I get back from a business trip in a couple of weeks, how do I prevent this from happening? Can I apply WD-40 now and clean it off later with mineral spirits and pre-paint cleaner?

 

i wouldn't reccommend that by any means. putting WD-40 on something that is to be painted later opens up the possibility of the paint fisheye-ing, no matter how clean you try to get it.

the only thing i ever do to preserve bare metal until i'm ready to spray is dust on some etch primer. it needs to go down before primer surfacer anyway, so you might as well just spray it. it would take no more time than spraying it with WD-40, and etch primer dries incredibly quick. i would seriously reccommend etch priming ASAP.

if you can't even do that before your trip, try drying it off completely and storing it inside where it can't get wet. then you'll just have to take your chances on having it build up some surface rust.

 

I was going to spray the bare metal areas with some rattle can primer but the actual primer I'll be using is House of Kolor epoxy primer which says not to spray over any non-catalyzed primers. I guess it's better to sand off that primer than dealing with solvent pop.

 

true, anything's better than dealing with solvent pop haha. but... you won't have to worry about anything. first off, if anything would happen it would be fisheyes.. not pop. second, the only reason they tell you not to use non-catalyzed primer underneath 2K catalyzed primer is that 2K hardens, but rattle can paint dries. it has no hardening properties at all. over time, it will "sink" underneath the 2K primer and show up under the clear. etch primer is not the same as regular high build rattle can primer. where as high build goes on thick (the reason it "sinks"), the etch primer is very thin. it also has the self-etching properties that high build doesn't.

etch primer goes down under anything, catalyzed or not. it bonds itself to the metal, and dries almost instantly. you can spray any 2K catalyzed primer right over top of it. actually, when cutting in rad supports that have just been put on, i etch prime over the bare spot welds, and then spray basecoat directly on top of the dry etch. it's not something that's going to give you problems down the road like it would if you use high build rattle can primer.

either way, just make sure to cover it up. any coating is going to be better than no coating. it's up to you whether you want to sand it off later or not, but with the self-etch you shouldn't have to.

 

That's excellent information. Thanks for posting that up. I'll pickup some etch primer to keep around the garage for situations like this. Thanks again!