Paint chips in relatively new paint job

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PostPosted: Tue Aug 30, 2022 12:16 pm
I completed my first paint job last fall and, although there were certainly challenges, the results were....passable. I buffed through the clear coat in one small spot on one door and there are some places that have a bit of an orange peel but, overall, for the first attempt, I am happy with the results.

Or at least I was.

By spring, I noticed a few chips in the hood. At first, I thought little of it but the number has increased dramatically over the last few months.

I already know that I'm repainting but the question is: is this caused by poor preparation before the base or by clear coat that was too thin? Perhaps both?

The leading edge of the fenders also have a couple of chips but not nearly as many as in the hood. The leading edge of the roof is also still solid.

Thanks in advance.
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PostPosted: Tue Aug 30, 2022 12:35 pm
Since I changed to using epoxy primer on all my bumpers and hoods
I have noticed a huge decrease in road rash.
Epoxy really increases adhesion.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Tue Aug 30, 2022 3:12 pm
:goodpost: the epoxy really helps but your still going to get chips. i just painted my car ( 5 months ago?) and have a chip right on the nose of the hood. i'm going to leave it for now, BUT i'm going to take it up to my boys shop and have the clear bra material put on the front of it . i would have to paint the hole nose of the car ( front of doors forward) to fix it. big job to make it look as it did before.
Jay D.
they say my name is Jay

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PostPosted: Tue Aug 30, 2022 7:13 pm
As above, epoxy really helps, as does activating the base coat, but big chips like those usually say to me that the paint is too thick.

Can't see from the photo, but what is the white layer that's now visible?
Chris



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PostPosted: Wed Aug 31, 2022 8:05 am
Epoxy primer eh? Interesting. I used a urethane-based primer. I don't expect never to have a chip but I have picked up more chips in the last few months than in the previous 20 years.

The white is primer.

Now, the paint being too thick is not something I considered. Do you mean that one (or more) of the coats was put on too thick or that there were too many coats?

The rest of the story is that I mistakenly only used plastic masking the first time. I subsequently learned that paper should be used near the area that is being sprayed otherwise excess paint on the plastic turns into flakes and blows all over your newly laid paint :( I let the two coats of base I had applied sit for 36 hours then wet sanded it to eliminate the flakes which can be seen below. I resprayed the base, again two coats, followed by the clear.

There's also a defect on the hood which I attributed to a failure in preparation. It can be seen in the images below as a line in the paint. It's been there for several months and hasn't changed. It's not lifting or expanding in any direction. I can't help but wonder, now, if this isn't also an indication of paint being too thick.

One last note. As mentioned, I effectively sprayed the base coats twice yet the chips and defect pass through all of this down to the primer.

Thanks again for the guidance.

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PostPosted: Wed Aug 31, 2022 8:22 am
You did sand your urethane primer, right?
You also should never wet sand base, it can soak
up moisture so I hope you gave it a long time to dry.
I'm just trying to figure it out, that chipping does look excessive to me.
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Wed Aug 31, 2022 8:41 am
Hey JC, yes, the primer was sanded.
Oh, I'm keenly aware that base shouldn't be sanded but there was no option. The flaking was severe. It basically snowed paint flakes all over the base. It was an absolute pain to get it to a smooth surface. In all, it took almost a week of evenings to get it to a point I was ready to try again.
That said, the fact that it's chipping straight down to the primer makes me think I didn't prepare it properly. It was all sanded with 400 though and I'm not running into any problems anywhere else on the car.

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PostPosted: Wed Aug 31, 2022 11:08 am
Well if it's down to the primer, then the base is what's not sticking, right?
So I think there's something wrong with the base adhesion.
400 grit is more than enough tooth for base, I usually use 600
and that's industry standard, sanding is not the problem.
Maybe the primer got contaminated before the base was applied?
Just guessing,
It could even be a air source contamination from the compressor.
or residue from a tack rag.
Sometimes contamination problems are real hard to trace.
I don't know. :(
JC.

(It's not custom painting-it's custom sanding)



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PostPosted: Wed Aug 31, 2022 11:24 am
:clap: you passed the plastic masking course your diploma is on the way. they have plastic masking that the paint doesn't flake off ,so they say. i still like to paper out 18" or so. it sounds like you did everything right. it also sounds like its the adhesion between the primer and base coat. you said you sanded with 400 it should have provided a good mechanical grip. did you wipe the primer before the base? how did you apply the base light, med or heavy wet coats? my gut feeling is its one of those things that happen, it happened to me and i was very careful about what i did. i used a wet on wet sealer. a tip, next time use a dark sealer or primer under dark colors. at least it won't show up so bad.
Jay D.
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PostPosted: Wed Aug 31, 2022 12:45 pm
Yeah, that was a lesson learned the hard way but not a mistake I'll make again. ;)

I was very careful to keep things clean and dry between coats but clearly, something went wrong. The only reason I question whether it was an adhesion problem between base and primer is that I expect flaking. Maybe it's just a degree of failure though; not bad enough to flake on its own (yet), but bad enough that stones cause it to pop.

All this said I plan to sand it all down again but planned to stop once I got through the clear, use a little spot filler and sanding to eliminate the chips, prime over the filler, and carry on with base.

If I'm reading this all correctly, the recommendation is to put a coat of epoxy primer down first, then urethane, base, and clear. Will the epoxy bind properly to whatever remains of the base coat? For better or worse, I've been using Nason products. 421-10 primer.

Thanks again, and again.
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