How to remove rust and protect from rust on just a small area?
 

I recently bought an old road bike (1979), and the paint is in really good condition, except for an area on the fork where there's some rust, maybe 1 square cm. All the sites I've seen on the subject are about restoring all the paint on the whole frame, stripping, etc. I want to keep all the original paint that's on the frame, and just prevent this area from getting worse. I don't care about making it match the yellow paint that the rest of my frame is. Would I just sand the rust (or use oil and steel wool), then a primer, and... I don't really know.

Thanks

Steel wool and oil is only for chromed areas or for blued firearms. Don't use the steel wool on painted areas. The same goes for anything abrasive like sandpaper or the green fiber scouring pads. If you're not planning on a full paint job then avoid anything at all abrasive.

If they are just small spots and you don't want to do a whole paint job then one option is to get some oxalic acid at a good hardware store or something called "Bar Keeper's Friend" from a specialty kitchen store. The BKF has oxalic acid in it. Wash the rusty spots with a paste made of the oxalic acid or BKF using a non abrasive sponge. This will remove the rust stains and cut back the rust a lot. Following that rinse and dry well and treat with a rubbed on and wiped off coat of boiled linseed oil. Wipe it off vigoursly without worry. Enough of the oil will stay in the rusty spots to dry and seal them from further rusting. And for extra protection after the oil dries for a week to 10 days put on another coat and wipe off. The oil stays really sticky for a long time so you don't want to just oil the paint and leave it. That's why you put it on and wipe most of it off so it'll dry sooner. Actually it goes through a chemical change where the oxygen oxidizes the oil so it polymerizes to a solid film. But enough is left in the low and rough rust spots even after wiping it away vigoursly to protect.

Thanks! I have BKF, and may even have boiled linseed oil. This will be cheaper than I was afraid it might be. :-D

On small spots, clear fingernail polish also works well at protecting from future rust.

If your intent is to repaint the spot, I would not use any oil on the area as no paint will stick after application. I have, very carefully, and this is where a dremel tool is handy, sanded the area and applied a rust converter(available in any auto parts store) as primer and painted over this with correct color oil base paint.

Hmmm. I do have a Dremel.

If it's just light surface rust,use a pencil eraser.Clean and coat with fingernail polish.

When I rebuild bikes and encounter rust on painted surfaces a small chisel knife blade come in handy to scrape away the rust. Wear reading glasses so you can get in close. You should be able to scrape off the rust right down to the bare metal. From there some damp baking soda can be used to polish the rework area. Then you can touch up using model paint or fingernail polish.

I have some boiled linseed oil, rust reformer, Barkeeper's Friend, a Dremel, primer, and yellow paint. I think I have everything I'd ever need to take on this "project."

Tell me if this makes sense to do: BKF, sand, then rust reformer for any rust leftover, sand, primer, sand, paint? I've never done anything like this before. :-\

It depends on how you wish to leave it. If you're going to clean up the spot and go for touching up the paint then by all means sandpaper around the area to feather the paint and at the same time sand away the rust is a fine idea. Then from there you go onto the paint touchup. If the spots are just little things with some staining on the paint surrounding the little chip and all you want to do is "kill" the rust and seal them so that they don't keep staining the paint and bloom out to a crusty brown spot then the BKF treatment will cut back the current crustiness and clean out the chipped spots. From there you can seal it with the boiled linseed oil or with some clear nailpolish as mentioned. Or even some Flecto Varathane varnish if you wish.

If you'd like to touch up the chips with paint and they are just little spots then here's something you can try. I've done this same thing on a couple of bicycles of my own as well as the wife's brand new motorcycle back when I managed to "oopsie" it while installing her saddle bags on the bike. If it can pass the "pissed off wife's new motorcycle" inspection and produce a smile then you KNOW it works.... :D

1. Clean the spot out with the BKF to kill and remove the rust.
2. Mask off the area around each chip with masking tape about 1/16 away from the edges of the chip.
3. Wet sand the spot with 400 grit wetordry paper to feather the edges down into the chipped area. Dry and replace the masking tape as required if it cuts through at the edges and can't limit the sanding to that 1/16 "rim".
4. Once sanded to your satisfaction peel away the masking tape and dry the area. When competely dry use your touchup paint to fill in the spot starting with the first coat just in the middle of the chipped area. After a day add a second coat that is a little bigger. After another day add a third coat that extends out to the edges of the sanded area. If needed continue to add coats at one per day until the area is built up just a touch higher than the surrounding paint job.
5. At this point just leave it alone for a week to thoroughly dry and harden. THIS PART IS IMPORTANT! "New" paint stays soft for at least a week as it takes that long, and longer, for the paint to fully release the solvents. Until those solvents are gone the paint will not be able to be worked well for the follow up steps. Patience is a virtue here. This is NOT a fast fix but it works.
6. Now that a week, or preferably two, has passed remask the area again leaving about 1/16 inch of original paint all around the raised touch up bump(s). Wet sand it using 400 or 600 wetordry paper as appropriate depending on how much of a bump you need to removed. The smoother it is the less coarse the paper should be. Only use the 400 for the initial working down then switch to 600 for the smoothing and blending to the surrounding original paint. Once blended remask to expose about 1/8 inch of the original paint and switch to 1200 grit wetordry used wet. After smoothing it with that switch up to 2000 grit.
7. The sanding is all done so remove the masking. At this point use a clean rag to polish the spot(s) using autobody Rubbing Compound. After that switch to autobody Polishing Compound. And finally a good "deep cleaning" automotive wax for the final step.
   
   Yep, there's a lot of steps. And if there's more than 3 to 4 chips to repair it's likely easier to look at a complete strip and re-paint. But if there are only a few spots or it's a finish that you won't be able to match without spending a fortune this may be an option for you.

Wow, thanks for that reply! The rust spot I'm dealing with is about the size of a nickel, on the fork. It sounds like I should have brought back all my razor-polishing sandpapers and rubbing compound from where I'm storing a lot of my stuff. That's all right, I won't need that for at least two weeks, and I can get it in that time. :-D

So no Dremel should be necessary. BKF and sand paper should do the trick. No rust reformer, either. I don't think I need this to look as nice as your pissed off wife's new motorcycle, though. :-D This bike is from 1979 and the finish isn't perfect all over (not bad, just not perfect). I better take some before shots before it's too late!

Thanks again, good ol' BCRider.

Well, I've never done a nickel sized spot. But there's no reason the technique won't work just as well. You'll just need to use something to support the sandpapers so that you don't just sand "waves" into the spot of that size.

Please let me know how it works out for you if you go this route. I'd be interested in how it fits with that size of damage.

I looked again. The spot is nowhere near the size of a nickel. But it's in a tricky spot. A corner. There are a few other rusty nicks I might practice on first, even though they're in more visible places.

I don't know how easy this is going to be without taking the bike apart. I suppose I could take the brake off.

http://imgur.com/gHJuB.jpg

For spots like under the crown like that I'd just kill and remove the rust with the BKF and then smear on some paint and call it good. You won't see that spot in normal day to day riding at all. Instead all you need to do is protect it from further rust formation.

Also without meaning to be cruel or insulting I'd suggest from the looks of the crown construction that this is not a frame that is worth spending a huge amount of time and money on. Classic frames use nicely cast lugs and crowns while this uses a kludge of stampings welded or brazed together. By all means clean it up and enjoy riding it but it's likely not worth the time and effort to run it through the paint matching method I described above.

No offense taken. I know this is an old Sears bike. Heck, I only paid $25 for it. Plus the price of new tires (as you can imagine, the original 1979 tires were pretty well dried out). Better to learn how to do this sort of thing on a piece I can't ruin too badly, before I have to work on a pissed off wife's new motorcycle, right? :-P

And now I have primer and a nice yellow paint that I can't paint almost anything with. :-D Hide your kids and pets.

I appreciate all the input.

You're having fun and learning a lot that'll serve you well on the next bike. So it's certainly all worthwhile.

CHeers and happy miles.

For spots like that one, I just use one of the rust converter products. You can find it at Walmart in the auto paint section. Then top coat it with testors enamel.

I hate to hijack the thread, but this advice is very good and very close, but not exactly what I am looking for.

I'm building up a frame I picked up at a swap. All the visible paint is in excellent condition; although, there are some chips on the derailleur hanger and around the brake bridge. No rust has formed yet.

I’m not concerned about how these spots look, but I do want to protect from rust AND protect the paint from chipping further.

Any suggestions?

After cleaning and degreasing the paint in those areas wipe on either some polyurethane varnish to seal the exposed steel or just wipe on a couple of coats of boiled linseed oil over a few weeks of drying time. Or if you're patient and use a very small pointed touch up brush you could fill each chip with polyurethane or even a color matched paint. If you use the wipe on and off method then wipe off most of it that is on the actual paint working to leave most of the coating in the chips and on the exposed metal.

There's likely some other options that folks will post but they'll all be some variation of this. I'd avoid the usual clear nail polish idea since I've always found nail polish to be quite brittle and to flake off pretty easily the couple of times I've tried it. Now I stick to proper paint, varnish or the boiled linseed oil options.

Nothing at all will avoid the paint chipping further if it has broken the bond to the base metal over a wide area. The touchups will leech under a loose edge to some degree and hold down the edges of the chips you touch up but if the paint bond isn't strong overall you could still get pressure chips at the edges of the present chips or from future spots. If the frame's paint seems to be a little fragile the only good option is to treat it well and don't lean the paint against stuff that will marr the finish. Always a wise option in any case for any bike that you care about.

I’ll give the polyurethane route a shot and see how it goes.

The frame builder has a reputation of creating spectacular looking paint jobs that unfortunately tend to be a little fragile, and I tend to be hard on my bikes.

Other than gentle handling, is there anything I can do to protect the paint?

Short of finding a compatible space age clear top coat there's nothing to be done about it other than care. Even that may not help if the paint used only has a light grip on the primer and the same with the primer to the base metal.