rock chip repair

marko · 09-20-05, 08:56

I've decided to take this on as an ongoing project, but after researching I'm undecided about which of several paths to take. I'm going to end up trying everything but would appreciate reading about some real life experience. touch up and wetsanding with a 2k unigrit block and polishing seems totally reasonable. I'll probably even try the touch up and clay idea. then we have the langka blob eliminator and wet sanding systems. for the record, I'm looking at a couple of issues with my 97 acura: fresh rock chips and an older and extremely poor scratch touch up. can anyone offer some advice?

Accumulator · 09-21-05, 07:30

I haven't used the Lanka, but I've done other touch ups. To do it right you oughta use an airbrush (there's a *great* thread showing what's possible) but I've never tried that either.

What I *have* tried is the "traditional" apply paint/sand/polish. Never turns out great but sometimes it's better than leaving the chip. But then the chips that I just let go on my Jag are fine after 20 years and as the museum curator said, "real cars have stone chips"

Anyhow...

Clean out the chip with solvent. Mask off surrounding area with a little tape to avoid an "oops". Use some 3K paper to smooth the edges of the chip if they're really ragged and maybe sand the "bottom" of the chip a little too (I'll often use the corner of a 2.5K sanding block for this). Apply "Rust Avenger" if the metal has been exposed and has rusted. Apply paint, color coat first. I apply the paint with either a carefully cut/shaped tip of a paper match or a small artist's brush (size 00 or smaller). Multiple layers, put on thin (I usually get properly thinned paint from my body/paint guy, the touchup stuff is often too thick). Build up the color coat until it's just below the level of the existing paint and then apply some clear. Let it dry. Sand with 2.5 block or 3K paper w/sanding block. Polish out with 3M PI-III RC (05933) then PI-III MG (05937). I let it cure before applying a wax/sealant but many just wax right over the touchup.

Picus · 09-21-05, 07:42

If you click on the link in my sig you'll see what can be done with some patience. I filled in and sanded/polished 60+ chips in my hood/fenders/bumper cover. I used 2k-3k grit sandpaper and will recommend using 3k grit, the marring is much easier to take out after you sand and it does the job just as quickly as 2k grit. Accumulator, as always, has the process down perfectly. The only thing I did different was I used a plastic toothpick to apply the paint using capilary action. This can take a long time (some of my chips took 5 coats), but when you're done the 'blob' is almost unoticable even before sanding. I actually left 20 or so after the repair and will jsut polish them as normal when I polish my car yearly.

I let the repairs cure for 48 hours before polishing. I used Poorboys SSR2.5 and Optimum compound to take out the marring, I would recommend Optimum or the PI-III RC that Accumulator mentioned. SSR2.5 popped some of the chips out. After that I sealed right over the repairs, but letting them sit for awhile will probably help them in the long term.

papi_jay · 09-21-05, 08:02

You scare me picus .

Picus · 09-21-05, 09:08

Quote:

Originally Posted by papi_jay

You scare me picus .

Is that good or bad?

papi_jay · 09-21-05, 09:13

just scary . you filled over 1000 chips and such ... Wait until you hear my chip filling story before I found autopia .
Advance notice - it is not gonna be pretty .

Picus · 09-21-05, 09:47

Well, to be fair it was only 100 or so.

I can't wait to hear the story. I did some whacky stuff before I found autopia too (what do you mean I can't clean my car with a broom?)

marko · 09-21-05, 01:49

hey thanks very much for the input.

Accumulator: it appears I'm at least on the right track with the wetsand / polish method other than that 2k grit is the finest I have (at the moment). you think it's a mistake to attempt this with anything other than 2.5k-3k?

as for picus (aka: oh great god of all that is paint chip repair; aka patron saint of rock chipped bumper covers and hoods and (yikes) panels having fallen victim to shopping carts), I'd prefer to think that shopping carts don't scratch cars, people do. no matter really as the effect is the same. suffice to say I aspire to your level of determination. my girlfriend, I'm certain, will feel otherwise once my oc process begins.

I have at least ssr2.5, ocp, and occ to combat the sanding marks, so I think I'm good there.

still, I'm bound to try every method imaginable and am curious if y'all have any idea what might substitute for the "blob" reducer in the langka kit.

Picus · 09-21-05, 02:00

Hah, thanks for the compliments. I am not sure I deserve them, but I will take them.

I am not sure if there is a product similar to langka, but I have used langka and it does do a good job on *new* chip repairs if you use it very carefully. However, it will not remove the blob such that you won't be able to see it at all, you will still see it on some angles. Also, when i used it it popped out about 1/2 of the chips I used it on, so be very ginger when using it. Clay can also work if you rub with some elbow grease and lubricate well. Actually, someone posted that meg's scratchx does a decent job of leveling blobs too, but I haven't tried that. I personally like wetsanding better because when you're done the chips are 100% gone, but there is a risk there of course.

RE: wetsand, having used 2k, 2.5k and 3k I would *highly* recommend getting some 3k. It will remove the blobs as fast and the marks truly are much easier to remove. 2k is fine, but it may take 2-3 passes with SSR2.5 and some serious pressure to get the marring to a level you're happy with. With 3k they will come right off, you will be amazed at the difference, I was. I personally won't use 2k again because (and this was my fault) I ended up scratching one touchup on my door a little too deep and now I have a fine scratch rather than a chip. With the 3k there is much less risk of that. I am interested to see what Accumulator thinks. My detailing knowledge is a drop in the bucket compared to his, so he might have some ideas on the 2k that I didn't think of.

So I guess what I am saying is if I were you, I would sand with 3k, then polish with OCC first on a cutting pad to see if that does it (it should), if not try the SSR2.5, but I really think the OCC will do it, then you can follow with OCP and have an awesome finish ready for your LSP.

Let us know how it goes. I know what you're in for and it's a lot of work but it can be very rewarding. Good luck!

Accumulator · 09-21-05, 03:25

Picus- Nah, we're on the same page on this one. No matter what I'd using an abrasive on, I try to only use what I really *need*. You know, it's the old "you can't drill a smaller hole" thing...

Quote:

Originally Posted by Picus

... if I were you, I would sand with 3k...

Yeah, it's *far* easier to make an "oops" with the 2K. And when it comes to removing the sanding scratches *without using a rotary* the difference between 2K and the finer stuff is significant.

Marko- Order up some Unigrit in 3K, it'll be worth the wait. Really.

marko · 09-21-05, 09:36

hey man, sorry for the delay. I've been on task at the office. seems this work thing really gets in the way.

okokok. understood. I've been bringing this particular car back into shape from the ground up over the last year, so I'm patient. I have a pc and rotary, and I'll delay gratification and order up some 3k.

while I have your attention, what's the half-life of these finishing papers? I mean, realistically, what's an adequate supply for the task at hand and / or how do these sheets perform? any metric will do: no of blemishes vs area. are we talking about a couple of sheets or a couple of dozen? man I don't want to run out mid-task.

could you also comment re: wetting solution and backing pads? I want to do the right thing.

as for the advice, by the way...

Picus: anyone attacking a hundred or so anomalies on a single car, well, I've seen your post and appreciate your advice.

and Accumulator: I've seen and read of a fraction of your work, so thanks.

Picus · 09-22-05, 04:20

When I got the 3k grit I got a 6 pack of the 4x4 variety, I think I used 4 or 5 but that was on 60+ chips - you can pre-sand and sand after the touch up with a small portion of the same peice. You don't really need a lot.

For a backing plate I used a little peice of rubber I bought at a hardware store, I'm not really sure how to describe it other than it was pretty firm rubber (like an eraser) about an inch wide and 3/4 long and maybe 1/2 inch thick with a slightly curved edge, like a half moon facing outwards. Maybe I will take a picture, but a regular pink eraser would probably be ok. Anything that is firm with a little give.

My wetting solution was just water, I soaked each peice over night. I cut the individual peices before they were wet, which I think helped. Oh, I used regular old rubber epoxy to put the paper on the rubber, I let it dry for maybe 30 minutes then went to work. I probably removed the peice after 3-5 touchups depending on the size then glued another one on.