Rock chip...with rust

CocheseUGA · 10-06-09, 04:53

Thanks to all the recent heavy rains (500 year floods, that's all), I haven't had the opportunity to care for the car. On Saturday, I finally got an opportunity to wash, and noticed the rock chip I had seen a few weeks prior was actually much worse than originally thought, and had gone all the way to the metal. Now there's rust in that eraser-head sized spot.

Unfortunately, a hood replacement or strip and repaint is out of the question tat this point and time. Are there any DIY alternatives? I just got my PC, but I have zero experience. Basically, I'm okay with treating it and actually fixing it some time down the road when expenses like roof repair is off the table. I don't want it to spread under the paint or eat through. If there's a way to inhibit it, I'd be very interested in knowing.

Setec Astronomy · 10-06-09, 05:04

You need to sand off the rust, prime it, and touch it up. You probably won't like the way it looks, but it will look better than a rust spot and it will stop spreading.

CocheseUGA · 10-06-09, 07:40

Hmm...I wonder if I can do it without messing up the surrounding paint.

Setec Astronomy · 10-06-09, 07:48

They make special sanding tools for this. Some guys use a hole punch to cut out pieces of sandpaper and glue them to the eraser end of a pencil. There are some threads on here that you may be able to find.

Accumulator · 10-06-09, 08:00

CocheseUGA- You should be able to do this OK (not perfectly, but OK).

Mask off the surrounding areas.

There are "rust pens" that have abrasive filaments made out of fiberglass, these are used to "erase" the rust and will get most of it. These days I get mine from a catalog called "MicroMark" (do a google and you'll find their site). They sell large and small ones, I'd get both.

Then treat the exposed area with a rust converter. With my fave now off the market, I'd go with the stuff from Eastwood Company: Auto Tools, Body Repair, Classic Car Restoration, Paint Guns, Powder Coating, Soda Blasters, Fender Rollers . For small areas, it'll work OK as a primer but using a real primer is better.

A great primer is Eastwood's Rust Encapsulator, but it can have issues when topped with a lacquer touchup paint, and most all of them *are* lacquer.

Then touchup paint/etc. per usual.

The above is *NOT* as good as spot-blasting or other more professional approaches, but it's worked perfectly well for me countless times. I've even gotten away with using lacquer touchup paint over the Rust Encapsulator, but that's kinda a one-out-of-six situation because the lacquer stuff wants to do a solvent action on the Rust Encapsulator; maybe you'll pull it off, maybe you won't.

For a crappy-looking, but functionally good repair, just use the Rust Encapsulator for the touchup paint and/or top with some enamel like Rustoleum. It'll make the chips look like, well...chips; like they're down to primer or something. But at least the rust will be arrested so it shouldn't get worse. I'd rather have to-the-primer-looking chips than rust any day.

pasadena_commut · 10-06-09, 08:44

Quote:

Originally Posted by Accumulator

Then treat the exposed area with a rust converter.

I suggest you do NOT do this. I just tried rust converter on a large number (50?) of tiny, rusting, rock chips on the leading edge of my hood, and the rust converter discolored the surrounding (white) paint slightly. Rubbing it with alcohol removed some of the stain, but some remained. Since you only have a single chip, you might as well just sand it all the way down to the metal, prime, and paint.

Post treatment my hood looks pretty crappy, but not as bad as it did with all the chips untreated. Before, at a distance there were obvious dark spots all along the leading edge, and these could be seen 20 feet away. Now from that distance it looks fairly good. However, up close each treated spot is a slightly different color than the surrounding paint. It will do for now, but a repaint would definitely have been the way to go for the best results.

XRL · 10-06-09, 08:51

I've got to keep an eye on this... my ex-gf/roomate/it's-complicated has a spot on her roof with some light rust (i think). Damn rock chips. I just don't want to deal with all the wet sanding and nonsense for a tiny spot on the roof, that might not even have rust.. it might just be the same orange staining junk from the tree...

Accumulator · 10-06-09, 09:29

Quote:

Originally Posted by pasadena_commut

I suggest you do NOT do this. I just tried rust converter on a large number (50?) of tiny, rusting, rock chips on the leading edge of my hood, and the rust converter discolored the surrounding (white) paint slightly..

Huh, never had that happen

I'm assuming you didn't let the converter overflow out of the chips onto the surrounding paint, right? You *do* need to keep it off paint and only apply it to the area you want to treat. Any contact with paint spells trouble.

Seriously, I've done this countless times, with (IIRC) three different rust converters, and I've never had it do anything except neutralize the rust it came into contact with, except when I slopped it onto surrounding paint and failed to wipe it off right away.

Guess it just goes to show that you need to be careful because YMMV always applies.

The reason I'd always use the converter is that unless you blast there's always a risk of some miniscule amount of residual rust. The old acid-wipes/etc. never killed it 100% IME but the converter almost always does.

CocheseUGA · 10-06-09, 09:35

Thanks Accumulator. Should I go ahead and get this done this weekend, or will it keep until next?

Accumulator · 10-06-09, 09:57

Quote:

Originally Posted by CocheseUGA

Thanks Accumulator. Should I go ahead and get this done this weekend, or will it keep until next?

As they say, "rust never sleeps", but I don't think one more week is gonna make any big diff. I'd rather do it right (with the right stuff) a week later than do it half-@$$ed right away.

pasadena_commut · 10-06-09, 10:30

Quote:

Originally Posted by Accumulator

Huh, never had that happen

I'm assuming you didn't let the converter overflow out of the chips onto the surrounding paint, right? You *do* need to keep it off paint and only apply it to the area you want to treat. Any contact with paint spells trouble.

It did overflow a little. That was pretty much unavoidable since most of these chips were so tiny. (They were probably from sand hitting the hood at highway speeds.) The converter was applied with a toothpick and that was still too large an implement for their size. Only on the two chips which were at least 1/4" across was I able to keep the converter just on the rust.

Accumulator · 10-06-09, 01:26

Quote:

Originally Posted by pasadena_commut

It did overflow a little. That was pretty much unavoidable since most of these chips were so tiny...Only on the two chips which were at least 1/4" across was I able to keep the converter just on the rust.

Ah, OK, that explains it then. Yeah, most converters will cause issues on paint (some a lot worse than others, the current Eastwood stuff isn't too bad) and in situations like yours it's a real problem. I gotta admit that when I have a situation like yours I just turn it over to my painter.

Maybe I've just gained some skill over the years, but I'm usually able to keep the stuff in the chip. But then I'm using a magnifying visor and tiny paint brushes for the smaller chips too and I'm usually only fixing ones that aren't too small.

With any luck, the one CocheseUGA is working on will lend itself to no overflow, and at least we've brought up the need to be careful.