cookie720 wrote:
Thanks for the reply!
Yeah roughing up good solid metal with 40 grit and bogging it is. But what about the rust that looks like its cancer (brown) and/or pitting. How bad does rust have to be before you have to cut it out and weld a plate in? I generally go when it starts to look like gold leaf and/or has holes in it, but if it still has a reasonable thickness to it after grinding, I will leave it...some spots however are different,
for example I took my rear left seam cover off to weld up a small hole in the corner right near the filler hole, and the seam all along there seems like its "melted" together. I got rid of the tar from the inside and wedged open the seam abit, and sprayed fish oil into it and it came through to the other side, which is good. Obviously I wont ever to bog the seam like some people do, but how do you go about bogging onto a pitted surface like that?
something like this is a perfect indication of what i mean, maybe even a tiny bit worse than this.

Im wondering if bogging on rust proofing chemical is a good idea...how about putting on the 3m stuff, and after that 40grit, that way if there are any pits or deeper bits where the sand paper cant get into, it will be *safe*.... I have never used any other primer than the regular grey one. Ive heard theres etch primer but it cant be used on paint only on bare metal bla bla bla...I hate over analysing everything before tackling a car. I do it every time even though the results are pretty good, no rust coming out of my first one
Nah, not at all mate, I'd rather ask 50 questions than stuff something up>
Ok, order of ops..
1. Strip paint back to bare metal
2. Treat with rust convertor (that 3m one is good, I have used it with sucess, just apply it with some steel wool or scotchbrite, let it sit for 20 min, then wash off with metho)
3. Key area with 40 grit paper
4. Apply bog
If you use the rust convertor properly, it will take care of the rust.
As far as how thin can you let the metal get before replacing it.. well it depends where it is, you get away with a bit less in some places more than others... but I'd say if its become weak the sensible thing to do is patch it
Does that help?
