Paint chip/scratch repair with Bondo putty questions.

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dfoxengr

New member
I was looking at the options to do paint chip repair and the Applied colors kit, which looks very nice, contains bondo spot putty. The idea is to fill before painting and I suppose the bondo shrinks less than paint so youll get a better total fill.



In the kit, they have a chemical used to remove excess bondo and paint. I assume this is just a solvent that can remove excess bondo, urethane paints (their paint is this type), and is also clear coat safe.



What could we guess is this solvent? Paint thinner? Acetone? Lacquer thinner? I want to try a couple little scratches on my own before I get a big kit and Walmart sells the putty + I'll use DR colorchip for the paint for the trials.
 
Still no responses to this, huh?



I myself have never done this bondo-touchup thing. If I can't get acceptable filling with a normal touchup routine I either live with the imperfection or have the area professionally refinished.
 
My experience with anything that has the brand name Bondo is, it's garbage, their body filler especially. I've used their putty and it shrinks - ALOT. It also does not have good adhesion IME. I've had great success with 3M's spot putty, both the red and green, they dry fast and minimal shrinkage. If you ever need to use a 2 part body filler, stay away from Bondo, it will peel and crack in a matter of months. Evercoat has the best body filler IME, and 3M has the best putty. Though all of my experience with body filler and putty is actual body work, not touchups, but I would say Bondo brand stuff would be just as bad for touchups as it will end up shrinking and probably peeling. YMMV, but I would not touch Bondo brand stuff with a 10 foot pole.
 
dfoxengr- It's been *decades* since I used such stuff, but I thought their "blue" putty was the fastest drying one :think: Eh, bet everything's changed since then.



But one thing that might *not* have changed is the way so many such products shrink/"die back" over time, long after they've "dried" and even "cured". (Heh heh, note those scare-quotes!)



Gee, I'm just a bundle of joy on this thread, huh?!?
 
dfoxengr said:
Hmm, but 3M makes the Bondo brand...



This one looks good since it dries quickly.

3M
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3M may make the brand, but that doesn't mean it's 3M quality, as it's branded under a different name. It's pretty much the same as the big auto paint manufacturers like Sherwin Williams who has their Sherwin Williams branded quality product, but then also manufatures a lower quality, budget priced line that is pure crap.



Yes, that's the green putty that I use, very much a quality product.
 
Ok, green it will be then, Thank you.



Explicit, could you do a test where you let the green putty dry for a couple minutes then wipe it with a towel that has laquer thinner on it? If that's possible that would really help as it is the method the paint chip companies show to fill scratches. The difference being they use their own solvent of some sort and the Bondo red putty.



Thanks
 
dfoxengr said:
Ok, green it will be then, Thank you.



Explicit, could you do a test where you let the green putty dry for a couple minutes then wipe it with a towel that has laquer thinner on it? If that's possible that would really help as it is the method the paint chip companies show to fill scratches. The difference being they use their own solvent of some sort and the Bondo red putty.



Thanks
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I would, but I don't have any at the moment. I only use it as a final skim coat for bodywork and don't plan on doing any of that till next spring.



Curious though, why do they show to wipe the putty with solvent? Never heard of that before, but I've never tried using it to fill scratches before touching up...
 
The idea is that the putty shrinks less than paint so the process would be something like

clean, putty, wipe with solvent (putty in scratch stays but putty on adjacent paint is removed), touchup paint, wipe with solvent again to remove excess paint.
 
I'd be worried about two things. The solvent having a bad long term effect on the surrounding paint and the solvent softening the putty. I wonder if you could use Langka instead of a straight solvent.
 
Many people use Lacquer thinner to remove decals right? The solvent is going to evaporate and shouldn't have a long term effect I wouldn't imagine. Anyone else have experience with this?



The touch up kit's "paint leveler" is a mixture of solvents. I think fairly similar to lacquer thinner but not positive.
 
dfoxengr said:
Many people use Lacquer thinner to remove decals right? The solvent is going to evaporate and shouldn't have a long term effect I wouldn't imagine. Anyone else have experience with this?



The touch up kit's "paint leveler" is a mixture of solvents. I think fairly similar to lacquer thinner but not positive.
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Ask Ron Ketcham what he thinks of using thinner on car paint. I used to use it until I saw one of his responses to using it. As a very experienced old timer who has pretty much seen it all, I trust his opinion NOT to use it.



EDIT: I was looking for Ron's post where he said to never use thinner on car paint, but I can't find it. Basically he said that there is a chance that it can have long term effects causing the matrix of the paint to fail over time leaving a dull area that cannot be corrected. It may never happen, but if it does, you may be paying for a respray on that panel. I wouldn't take that chance, and I can see how it could happen. Have you ever put lacquer thinner in a plastic cup and let it sit a couple minutes? Then go to pick up the cup and the bottom of the cup is melted the the surface it was sitting on? Not that paint is as fragile as the plastic, but I can def see how it can also have a bad effect on the paint.
 
ExplicitDetails said:
Ask Ron Ketcham what he thinks of using thinner on car paint.. Basically he said that there is a chance that it can have long term effects causing the matrix of the paint to fail over time leaving a dull area that cannot be corrected. It may never happen, but if it does....
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Yeah, just not worth the risk IMO. Plus, if you ever get it on some post-production paintwork (maybe something done at the factory/point-of-import that you never knew about), you'll learn what a great paint remover it can be.
 
My concern besides Laquer thinner would be filling the chip then creating a highspot once adding paint.



An ideal chip would be like an upside down Christmas tree. Each tier would be filled level to each subsequent layer then cleared and level. First primer then base then clear in layers. The problem with filling a chip with filler or basecoat then clear is going past the point of the actual layer in which it stops. Most often this results in a ring of base coat around the clear once Leveled.



Many touchup systems are lacquer based which will shrink under buffing if not fully cured and possibly react with some water based basecoats.



The best situation would be a catalyzed single stage enamel with an exact match then leveled and polished once cured. However that's not always possible.



I've done many on the nose of this from road tours.

jyramume.jpg
 
So if you're all saying that solvents are bad, the what do you think about Dr. Colorchip and others? They use a solvent to wipe excess paint from the repair areas?
 
dfoxengr said:
So if you're all saying that solvents are bad, the what do you think about Dr. Colorchip and others? They use a solvent to wipe excess paint from the repair areas?
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I keep the DR Colorchip solvent off the surrounding paint as best I can, sure don't let it dwell there. I guess it's like with Langka...these solvents probably aren't good for autopaint period but with, uhm....judicious use they don't *seem* to cause problems. At least they haven't for me (well, not yet).



Also, note that the DRC touchup paint is pretty fragile stuff, easy to clean/polish/solvent it right off the car even when you're being careful. A solvent that'll level that stuff (without removing it, at least as long as you're really careful and somewhat lucky!) could easily be mild enough to not damage oe paint or even catalyzed repaints and I've never had it mess up either (not that I've used it all that extensively).



I *do* wonder about using Langka on repaints, but I've done it without problems; I used it to remove blobby touchups from a repainted panel and it worked OK. But man-oh-man was I nervous about trying it, and I was being really careful to *not* let it dwell any longer than was necessary to soften the touchup paint in question.
 
dfoxengr said:
What did you do to neutralize/remove it so as not to let it sit there long?
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I do't really *neutralize* it, I merely wipe it off and it flashes away pretty quickly.



I'd hate for somebody to follow my example and have some terrible "oops!" but it's never bitten me yet.
 
So to bring this back, what solvent or method should be used to level the touch ups if Lacquer thinner isn't worth the risk?



Basically wanting to know what solvent is mild, but won't leave residue behind that I can level the filler putty and paint with. What about 3M adhesive remover, mineral spirits, etc?



Concours John?
 
dfoxengr said:
So to bring this back, what solvent or method should be used to level the touch ups if Lacquer thinner isn't worth the risk?



Basically wanting to know what solvent is mild, but won't leave residue behind that I can level the filler putty and paint with. What about 3M adhesive remover, mineral spirits, etc?



Concours John?
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The main problem with leveling fillers with a solvent is they are a catalyzed product. They need the chemical reaction to thoroughly bond and not shrink. Also their application method (spreading) does not lend to a non porus fill (resulting in shrinkage without subsequent primer layer fill). To remove them with a solvent needs to happen before that reaction has finished.



If you look at the composition of fillers there are different grades. Think of foam cell structure. The filler grades would range from fiberglass reinforced (coarse foam, loose density) to spot glazes(fine foam, tight density)



Wiping a filler with a solvent to level will just simply melt the outermost layer. Fillers should be removed by mechanical action, sanding.



There are reducers to thin fillers to change their structure a little. With the advent of products like "slick sand"(basically spray able bondo) it is not necessary. The liquid mix of these products leaves a less porous fill layer reducing shrinkage.(of coarse there are thickness limits.



Anytime you can fill with a liquid base you are better off on touch up work.



As far a solvents for paint. Most paint repair systems are going to use more of a paint reducer(less aggressive than thinner) based glob remover. These are going to be on the least aggressive scale.



I don't want to mislead anyone.

There are different grades of reducers and thinners. Basically it is their flash time that makes the difference.

Low temp tends to flash quick

High temp slow.



While one with and without experience can get a good result with any of these.

Picking the wrong one can cause problems at the scratch/chip repair perimeter. It's always best to talk with a paint jobber. Let him know your paint and ask for a suggestion. I myself always ask if unsure of a paint system reaction but know what to watch for when testing.



Forgive my rant I just wanted to explain more of why it is somewhat a technical question based on a system to system basis. Hopefully it helps.
 
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