How do I touch up over rust spots?

[amdrunner]

My car spent the spring parked so it got a bunch of buds, leaves and what not on it and when I tried to wash them off, they took the paint with them.

So what should I do to touch those spots up?

I was thinking of sanding it down and then using Ospho to get rid of the rust and then paint over it with a can of matched spray paint from NAPA. But I don't know if I could get it smooth enough on the hood.

Or is it possible to buff and sand the paint to get it relatively even?

[93forestpearl]

You sand/grind until all the rust is gone. Its the only way to remove it.


Then apply a finish as necessary. There is a cheap way to do it, and a proper way to do it.

[magicmike]

when you say it took the paint what does it look like now? It is bare metal where rust has formed or is it primer? A pic would be good.

[kimokalihi]

I too have been wondering this. When I got the car there's a few dings in it that rust is eating away at. I know it'll only get worse and every time I see them I sand to sand/grind all the rust off and primer it and clear coat it just to seal it and keep it from rusting again until I get the car painted, if I ever get it painted.

But I'm not body work guy, know nothing about it so I'm afraid of going about it the wrong way.

Do you primer it and leave it or clear coat over it to keep it nice and not rough? What is the proper way to do this as far as DIY-no-experience goes?

[amdrunner]

Here's a pic of the spots:

[93forestpearl]

You need to sand until you don't see any rust. Apply a self-etching primer (you can get it in a can) and match some color the best you can.


You can prime and paint over clear coat. Just rought it up with some 800 grit

[amdrunner]

Thanks for the help. I'll get on to sanding it, and post results once I'm done.

[kimokalihi]

I'll see what I can do. I think the rest is pretty bad and it's in a pretty good dent. I think I'd need to pull the dent first.

[magicmike]

your going to have to feather that edge out a bit or your going to have a step in the paint and you'll see the sanded area. I'd work the rust spot with a 120 grit and then switch up to a 400 grit and work around the spot so it is twice at big to feather the edge out. Then go to 800 grit and clean up the area your going to spray. When dry, wet sand it with 2000 grit to blend the overspray and smooth the part you sprayed. Use some polish to get the 2000 grit swirl marks out if any.

[evolutionmovement]

I'd use either a zinc galvanizing spray or rust converter before priming/as a primer, too. That spot is easy, but some spots are near impossible to get every spec of rust out of. You want to throw something on as a sealer if you just use primer, but the zinc spray or rust converter could be left alone for a little while, the zinc longer than the converter. Zinc is best for small spots and I would only use it if every bit of rust is gone.

3 cars dead to cancer, but this 4th one I've saved quite well.

[fishbone79]

For that spot I'd also second the etch primer, but add to that a couple coats of high-build primer. You can get all that in rattle cans.

First, use wax and grease remover before sanding (this is very important), then sand it out, feather and smooth, mask it off, hit it with the etch primer (2 light coats), and then use a build primer (2-3 wet coats). Once that dries, block it out with 600-800 grit wet on a good (read, nice and flat) drywall sanding block until it's creamy smooth and flat - use a cross-hatch sanding technique. Then I would color coat and topcoat with clear. You can clear-coat over 600-800 wetsand marks as long as you use a cross-hatch sanding motion (e.g., steps 1-2 here: http://www.autovations.com/images/blockbmp.gif). You will end up spraying a much, much larger area than the size of the original sore.

It takes practice to feather out over 4-coats of paint so it's indistinguishable; the build primer makes it a lot easier at no extra sacrifice. After the initial sanding to remove rust and feather out, all subsequent sanding should be done by hand. If you can feel even the slightest bump or a divit when you run your hand over the work, then it will show up in the paint. Be sure and use wax and grease remover before each coat (if you've touched it). Also, make sure you use a tac cloth between coats so you dont have any boogers in there. In case you're wondering why you should listen to me, see:

I hope all that helps!