Rust removal question

Hey guys,

I am going to be taking care of a developing rust spot before it takes hold - paint is starting to bubble in a 2 small patches of about 2"-3" in diameter just above the rain gutter over the passenger door.

I am expecting that when I sand it down I will find that I may need to cut away some of the lip that the plastic gutter is glued to.

I am not exactly an expert in body work, just wondering how aggressive I should be - isn't this a welded seam attaching the roof? Is there anything special I should be prepared for? Or just grind, sand, fill, sand, prime and paint as best I can.

Is there a really good rust prevention primer aside from just using the regular red or gray spray bomb?

Don't know if this question belongs here, but it didn't really sound like a "Fabrication" question and I didn't see a body work forum

OK, I'm an idiot - I see the body and paint subforum under modified tech.

I will go check it out.

Be forewarned... unless you can figure out how the water got through the paint, it is likely that the rust came through from the other side of the metal. There may not be much left. Figure out how the water is getting in, solve that problem, then be prepared to grind out the rust and either weld in new metal or make use of some window screening (behind the cut sheetmetal for some backing) and bondo.

Thanks Kastein,

I am thinking it may be coming up from the gutter lip. I am not bad with the bondo/fiberglass and hole patching for small areas, I am just wondering about that seam. I am thinking if I leave any corrosion at all in there it will just start to move along the joint - unless one of those rust converter products would help to slow it to an insignificant crawl.

Also, wondering if it would significantly affect the body strength in that area. if so, I would think about welding, but it is such a small area (I think, before getting a look below the surface.)