Strange pattern in new paint job - help!

[Trillion]

Hi there,

I realise this probably doesn't strictly fall under detailing, but I repainted the bonnet of my car, sanded it, buffed it and was left with this result..






As you can see, there's a strange pattern emerging as I buff out the sanding marks in the clear coat. I used a 2K HS clear coat, but accidentally (long day!) mixed it 1:1 with hardener instead of the recommended 2:1 ratio. I painted it about 2-3 days ago, so it's probably not completely cured.

What I'm trying to understand is why the finish is coming out like this, and not completely mirror flat. I've used 1500 grit to level the surface out as flat as I possibly can, and then used a compound to remove this, and I find this very consistent web of lines and shapes sitting on the clear coat..

The gun that I used to shoot all the layers was the cheap kit gun that came with my compressor, but I don't see how this would affect the final result as I've sanded it anyway..

Perhaps I should let it sit for a few more days to set completely? Could it be the heat generated by the buffer causing it to shrivel? Is this just a given with any paint job? Looking at my dad's new car, the paint doesn't appear completely flat. Anybody? I'm a bit stuck.

[scapegoat]

Re: Strange pattern in new paint job - help!

I would let it dry for a week . Then sand with 1200 , and reclear it . Good luck.

[jaymz]

Re: Strange pattern in new paint job - help!

OMG, it's JESUS in the paint. You're rich now. Sell it on eBay!!!!!!!!

Jim

[Trillion]

Re: Strange pattern in new paint job - help!

I would let it dry for a week . Then sand with 1200 , and reclear it . Good luck.

Thanks for the reply. Will the sand marks from the 1200 grit not show through the overlaying clear coat?

[Trillion]

Re: Strange pattern in new paint job - help!

OMG, it's JESUS in the paint. You're rich now. Sell it on eBay!!!!!!!!

Jim

I may just do that.. and then buy some keep-me-awake pills so I can actually get this sort of thing right the first time.

[daniel clark]

Re: Strange pattern in new paint job - help!

I shot transtar euro hs clear over 800 grit sanded clear...no problem here!

Thanks for the reply. Will the sand marks from the 1200 grit not show through the overlaying clear coat?

[RaskyR1]

Re: Strange pattern in new paint job - help!

Weird....the patter reminds me of some paper towels.


I'll have to show these to me old man and see what he thinks.

[Trillion]

Re: Strange pattern in new paint job - help!

I shot transtar euro hs clear over 800 grit sanded clear...no problem here!

So, you sprayed clear over pre-existing sanded clear.. these 800 grit scratches weren't visible after the next coat of clear was laid on? Did it not dull the finish at all? I'd rather not have to get it all the way back down to base as I'm not entirely sure how thick my base coat is and run the risk of cutting through it and having to start again :/

[Trillion]

Re: Strange pattern in new paint job - help!

Weird....the patter reminds me of some paper towels.


I'll have to show these to me old man and see what he thinks.

Indeed. I'm a complete novice - in fact, this is my first time spraying, but this just doesn't seem right. If you sand something, it should be flat.. but when the scratches are removed these things pop up. I'm not sure if they're being instilled by the buffing machine or whether they're hidden under the sanding marks..

[juliom2]

Re: Strange pattern in new paint job - help!

Sad to see that.........I don't want to carry bad news, but most likely you will have do it again.
Many of those crumble spots don't have great mechanical adhesion to the surface, an issue link to the chemical reaction
in the evaporation process ( not enough flash time, too many coats, below air pressure at the gun, mixture too heavy, resulting on thick coats)
Sanding with 800 and reclear could be an option but paint is laying down too poor.....
It might not result in the mirror finish you are after.....
Good luck with the project....

[Trillion]

Re: Strange pattern in new paint job - help!

Sad to see that.........I don't want to carry bad news, but most likely you will have do it again.
Many of those crumble spots don't have great mechanical adhesion to the surface, an issue link to the chemical reaction
in the evaporation process ( not enough flash time, too many coats, below air pressure at the gun, mixture too heavy, resulting on thick coats)
Sanding with 800 and reclear could be an option but paint is laying down too poor.....
It might not result in the mirror finish you are after.....
Good luck with the project....

Hmm, so is the problem with my paint layer or clear - or both? Could it have anything to do with the fact I mixed the clear coat 1:1 with hardeners instead of 2:1? The primer and base coat went on fine, but when I came to do the clear coat, it went on HORRIBLY. I wasn't sure what I was doing wrong, but it had fish eyes, a wavy texture to it, and it generally looked really bad. I'm gutted as this is actually the car I use daily, and only experimented as I had a few weeks off and was keen as I'd been interested in this sort of thing for a while. I've got a better spray gun on the way, a Devilbiss GTI, which I know won't make me any better at this, but it will at least eliminate the potential for the gun being at fault. Could anyone suggest ideal settings for shooting a good clear coat? Fan size, PSI etc..?

[bmrfan]

Re: Strange pattern in new paint job - help!

The pattern in your picture looks like there's some type of chemical "incompatibility" between the base coat and clear coat. Can't say if its related to the incorrect mixing ratio (1:1 vs. 2:1), general incompatibility between the base coat and clear coat or if there is contamination between the base coat and clear coat.

I've seen something similar at a prior job - our painting sub-contractor did not thoroughly clean out his paint guns between jobs - the resulting painted parts developed a "crinkle" like texture.

[juliom2]

Re: Strange pattern in new paint job - help!

With that said REDO is the way to go....!!!!!
Happy for your investment of the GTI......
Great tool to add to your hobby.....
65 psi is good when clear is shot..... also technique varies between initial coat and final coat of clear...
A little extra material wont hurt this great learning experience....

[Trillion]

Re: Strange pattern in new paint job - help!

The pattern in your picture looks like there's some type of chemical "incompatibility" between the base coat and clear coat. Can't say if its related to the incorrect mixing ratio (1:1 vs. 2:1), general incompatibility between the base coat and clear coat or if there is contamination between the base coat and clear coat.

I've seen something similar at a prior job - our painting sub-contractor did not thoroughly clean out his paint guns between jobs - the resulting painted parts developed a "crinkle" like texture.

Could this be caused by water in the system? I've managed to get hold of one now, but at the time of shooting this I didn't have a water trap. Also, I only flushed the gun through with thinner rather than stripping it entirely between the base and clear. These are water based paints, both were sold to me for use with each other at the same auto paint shop.. hmm.. perhaps I used the wrong thinner in the clear coat? I have a bottle marked with standard thinner, and a bottle marked with 2K thinner. I opted for the 2K thinner because I presumed this would work with the 2K clear..

With that said REDO is the way to go....!!!!!
Happy for your investment of the GTI......
Great tool to add to your hobby.....
65 psi is good when clear is shot..... also technique varies between initial coat and final coat of clear...
A little extra material wont hurt this great learning experience....

Thanks for the tips. Heh, I guess it is a learning process.. think I might be looking for a spraying course next year though! :P

I just can't think what might be the cause of contamination if it's nothing that's been mentioned.. I didn't tack the surface of the base coat down before shooting though. One other thing.. as I was short for time (it was getting late - noisy compressor) I sprayed the clear coat within 30-60 minutes of shooting the base, it may have been even less than that. Could this possibly have anything to do with it?

[Trillion]

Re: Strange pattern in new paint job - help!

Guys, I just realised something. I actually sprayed some paint on some scrap plastic to test it before shooting onto the car. Well, I sprayed both base and clear coat, in very light coats. I decided to polish it up to see if it came out with the same result, and it's actually mirror flat and completely without the funny marks in the paint on the car, which leave me confused.. The scrap panel was FAR dirtier than the car, and hadn't been cleaned at all. It was purely there to test spray pattern and that sort of thing. The difference is, when I painted the car, I put a lot more layers on. I probably put 4 or 5 quite thick coats of clear coat on.. I'm wondering if this could be the cause..