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-   -   Clear coat cracking (http://www.hotrodders.com/forum/clear-coat-cracking-229520.html)

Coaner 02-13-2013 05:43 PM

Clear coat cracking
 
I painted my truck in july of 2011. I was happy with the results and was excited about getting out the wax and the buffer for the first time this past summer but i noticed in the fall the clear coat on the hood began to crack. What would cause this the new paint held up great through its first fall and winter and shined up great this summer, why would the clear coat crack now? could the wax have something to do with it?

mitmaks 02-13-2013 06:07 PM

Can you post a few pics, which clear did you use. How did you prep/paint?

tech69 02-13-2013 07:45 PM

did you paint over cracked paint or lacquer check?

lukeembry 02-14-2013 06:08 AM

Quote:

Originally Posted by Coaner (Post 1646093)
I painted my truck in july of 2011. I was happy with the results and was excited about getting out the wax and the buffer for the first time this past summer but i noticed in the fall the clear coat on the hood began to crack. What would cause this the new paint held up great through its first fall and winter and shined up great this summer, why would the clear coat crack now? could the wax have something to do with it?


paint build up, too thick, too many paint jobs

69 widetrack 02-14-2013 09:32 AM

There could be many reasons why clear cracks...a few questions (like everyone else).
Is it the clear that cracked? or could it be anything underneath the clear, ie. bodywork, lacquer paint (as mentioned).
Are you finding clear cracking anywhere else especially a top panel like a roof?
What type of clear? Some clears are harder than others and if you have a combination of mil thickness of clear, body work (as clear, some fillers are harder than others and don't allow flex) and primers...If the primer is put on to thick or is a product that can go brittle after a while, cracks can develop.

The sad news is that you may need to take the paint down too and past the substrate to figure out what the problem is. It would be rare that if the clear was applied properly that it would crack without something happening underneath.

As far as waxing goes, I don't believe that would cause clear to crack....if anything it would cause clear to haze off. Some of the older high silicone content waxes seal the clear off to the point where over time would virtually suffocate the clear and cause it to die off.

Hope this helps...a bit anyway.

Ray

dinger 02-14-2013 11:01 AM

If there are any lacquer products, especially a spot putty like nitro stan, especially if it is a thick coat, this would cause problems. There's a lot of heat under the hood.

MARTINSR 02-14-2013 11:25 AM

Is it covered in cracks, or just a certain area? What is under that area, body repair? Can you take some photos, are they lots of little cracks or longer ones?

Brian

Coaner 02-15-2013 04:58 PM

Thanks for the replies fellas, first the paint is a single stage enamel which i the cleared with a urethane clear coat. the cracks are all over the hood

MARTINSR 02-15-2013 05:20 PM

Well there you go, your answer has been posted by others, uncured film and trapped solvents, you have both. That SS enamel can stay wet a long time, especially if applied heavy (read that a lot of overlap, slow gun movement, etc.) or too many coats too fast, too slow reducer, not hot enough surface temp, any or all of these things combined make for slower flashing and curing.

Now, under perfect conditions as I remember the window to apply clear over SS enamel is a much longer after the color is applied than say a regular Basecoat clearcoat. That is what I remember, but anyway you look at it applying clear over SS isn't the norm for a reason, it's a bit more temperamental.

Did you follow the tech sheet for recoat time and coats applied?

How many coats did you apply and how long did you wait before clear?

Brian

tech69 02-15-2013 08:20 PM

Not familiar with SS but that makes sense about longer flash times and a much longer than normal 45 min and clear, but I've never heard of solvents trapped leading to cracking...well, certain areas I've seen shrink up and sort of crack, but it's more or less like a rip or tear, but I could be wrong.

Was the car stripped? Was there originally cracks on the old paint that you thought you sanded out?

69 widetrack 02-16-2013 05:05 AM

Henry, I have to agree with you about trapped solvents leading to cracking...especially the type described by the OP. Usually trapped solvents lead to the top coat, in this case the clear either delaminating after a period of time or popping (solvent pops) or hair checkered cracking ...ie wrinkling. This wrinkling (looking like cracks) would happen right after the clear was applied...not 6 months or a year later.

I also agree that what's under the single stage paint in all probability is the culprit, lacquer putty, filler to thick or to much hardner in it, wrong type of filler used like short strand fiberglass, mat fiberglass with to much resin and hardner...who knows until it's taken down to the source but, in my opinion there's something under the single stage paint that's causing the problems....to much time has expired for it to be top coating the singe stag.

Just my thoughts.

Ray

MARTINSR 02-16-2013 09:10 AM

Coaner, can you post some photos so we can see exactly what you are talking about?

Brian

69 widetrack 02-16-2013 09:49 AM

I agree with you Brian, if Coaner could post pictures, we all would have a better chance of helping him figure out what is going on with his paint. What might be cracking to one person might be wrinkling to another. We're all relying on Coaner's description and the cause of the problem is only our "bestest" guess...LOL.

Ray

MARTINSR 02-16-2013 10:08 AM

Yep, sometimes it's a matter of semantics. :D


Brian

Coaner 02-16-2013 11:01 AM

I will try to post some pictures later im going to work on the truck. The cracking looks like somebody broke a hard boiled egg shell and is mainly on the hood all over it evenly. I didnt need to do any body work on the hood other than repair a few small dents. I painted the truck in July it was about 90+ plus that week using a slow reducer and waited longer to clear because i was told to when using the SS.


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