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Discussion Starter · #1 ·
I shot a car today with JP 202 (SHOP LINE- PPG) 2k surfacer and it started to blister. One spot was as big as my hand and peeled right off. I ran out of cleaner so I used mineral spirits to wipe the car with prior to priming and let it set for about 15 minutes and I'm thinking that wasn't a good idea to use that. Was it solvent trap?? I just made a whole extra day of work for myself :mad:
 

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To get a blister the size of your hand most likely had nothing to do with the cleaner. Could but something that big is caused by gassing or puddling of cleaner.

What is under it and when you peeled the bubble off did you look to See what was stuck to the back side?

Did it do it every where?? If it did, did you mix the right products?

If its isolated, than may be what was applied under it. spray can enamel?
Old enamel? Lacquer?
 

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STATUTORY GRAPE said:
I shot a car today with JP 202 (SHOP LINE- PPG) 2k surfacer and it started to blister. One spot was as big as my hand and peeled right off. I ran out of cleaner so I used mineral spirits to wipe the car with prior to priming and let it set for about 15 minutes and I'm thinking that wasn't a good idea to use that. Was it solvent trap?? I just made a whole extra day of work for myself :mad:
Mineral Spirits would be a no-no...you need a good wax and grease remover...lacquer thinner or enamel reducer is too harsh...whatever you wash it with prior to priming needs to be wiped off immediately so no residue is left on the surface...you'll probably have to strip the primer you shot off and redo it. :pain:
 

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Discussion Starter · #4 ·
O.K., here's an update: Last week I sanded the old finish on a car with 60 grit and sprayed MP 182 which is the 2K primer from the old line Omni before they switched to Shop Line (I had a can leftover). That held perfect, and I long boarded it with 220. I wasn't satisfied with the perfection so I decided to shoot it again with a 2K but had to go with the NEW line which was the JP 202 (Shop Line). I shot that today and it started to blister. This afternoon when it had dried I scratched through most of the blisters and found that EVERY blister was where the long board went through the first coat of 2K when it took down high spots and there was old paint underneath. It didn't do it everywhere just spots. Where the blisters are the primer didn't hold AT ALL. It was 80 degrees in the shop and the gun and primer were both warm and the primer was mixed well. Could it be possible that the mineral spirits dried faster on the primered spots and maybe soaked into the old paint spots? I've never had any problems like this before. It's basically all the "high" spots that are blistering so the primer would have to be taken off from those area's anyways when I longboard it again.
 

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My guess is it has to do with too thinly sanded original 2k or the original paint, and absorbtion or solvent attack. A place I worked at wiped down some parts with mineral spirits, its not real aggresive, but also doesn't do a good job removing contaminates from the surface. But painting over a surface that is wiped down with mineral spirits itself I haven't seen to be a problems, if the surface happens to be free of contaminates and the mineral spirits has been able to evaporate. I am not real sure on this one, but believe that a sensitive 1k finish or thinly cut primer is the root of the cause based on information so far. Why it didn't do it the first time if the paint you applied over is the reason is beyond me, unless the first coat happened to be applied dryer then this time. Or unless the cause is contaminates picked up, the mineral sprits or some problem with the original primer somehow. Is this actually blistering-like swelled bubbles, or is it lifting like crows feet.
Paint defect causes for blistering listed by ppg is
Cause
Moisture or contaminants trapped under the surface. This may result from:
a) Inadequate surface cleaning, leaving residual moisture or contaminants such as oil, industrial pollutants or grease from finger tips.
b) Incompatible materials or the use of non-recommended thinners.
c) Insufficient thickness of paint leading to increased permeability.
d) Water permeating both newly applied and aged films. Exposure to rain or high humidity before the finish is fully hardened increases the risk of blisters caused by permeation.
I think to rectify I'd sand out all the blisters and wait till you can get a better contiminate remover, and be sure to follow wiping on with a clean dry rag and allow a lot of time for that to evaporate before thinking of priming. Then don't hammer on the new primer coats, lots of flash time between. Somethingis getting trapped, you have contaminates or a sensitive surface.
 

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Discussion Starter · #6 ·
It was coming off the car like a rubber glove. There was no thinner so that isn't the problem. It happened on the first coat so it leaves out not enough flash time. The fact that it was ONLY on the paint surfaces and not the 1'st coat of primer is odd so contaminants seems unlikely. 220 shouldn't be to fine for 2K, right. Unless the mineral spirits didn't clean it well enough
 

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Discussion Starter · #8 ·
It was the correct hardener and I mixed it per instructions on can. It must have something to do with the paint. I'm going to let it set for a day or two and see if I can scratch any primer loose where it didn't blister. I don't want to have to sand with anything coarser because I don't want scratches.
 

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What I meant to say is there are solvents in the hardener and primer itself.
Good luck Grape. It kinda sucks if you don't figure out what the cause was even if all goes well next time.
What type of finish was it that you painted over?
 

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Brian Martin,Freelance adviser
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Rambo_The_Dog said:
Mineral Spirits would be a no-no...you need a good wax and grease remover...lacquer thinner or enamel reducer is too harsh...whatever you wash it with prior to priming needs to be wiped off immediately so no residue is left on the surface...you'll probably have to strip the primer you shot off and redo it. :pain:
Mineral Spirits are exactly what many mild "wax and grease removers" are! PPG's DX330, DuPonts 3939S, BASF's 901, S-W's R1K213 are all almost 100% mineral spirits.

HOWEVER, they are high grade mineral spirits and not the stuff you would get in the Mineral Spirits can at the "McHome" store.

Mr Grape, go back and read Barrys post. "Blistering" is "lifting" I assume by your discription. Lifting is caused by...

1. Substrates being too soft (lack of hardener like lacquer or 1K enamel and the like).

2. Substrates being too thin (sanded thin or applied thin).

3. What is UNDER the substrate wasn't prepped properly. Or a combination of these things, PERIOD.

Now, reading your "update" post, which one of these does your lifting fall under? Sounds like number three or possibly one.

Unless you really mopped the mineral spirits on and didn't wipe them at all, only leaving them to evaporate (totally incorrect use of a surface cleaner) I just don't think that was your problem. HOWEVER, it could have contributed to it in softening the old paint which may not have been a 2K.

Brian
 

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Doesn't sound like a case of wrinkling/lifting to me at all, I'd put money down that the old finish soaked up the mineral spirits where the cut throughs were and the new coat of primer didn't cure and adhere in these areas. If the primer is coming off these areas in sheet form like described then yeah there was contaminants on these spots and it was mineral spirits.
 

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Discussion Starter · #12 · (Edited)
I have pics so everyone has a better idea..... When I was priming and saw the first blister, I peeled one blister off about the size of the palm of your hand and primed that area again (so I primed, peeled blister, and reprimed blitsered area in about 10 minutes time). I checked the car this morning and that spot where I peeled the blister off and reprimed stuck just fine and is hard this morning with NO blistering. The pic with the tape measure is the one that I peeled off and reprimed. Why would it peel and then stick just fine again moments later? Thank God it's only the high spots that blistered :sweat: It should all blend fine when I longboard it again.
 

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Sure seems like the old finish sucked up some of those mineral spirits. I've pretty much switched to an H2O based cleaner, much better all around. Solvent cleaners only get used for removing adhesive and road tar etc.
 

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Discussion Starter · #14 ·
To all the people who think the paint sucked up the mineral spirits,, that's the direction I'm kind of leaning towards also. I just want to try to figure it out so I don't do it again. Sure glad it wasn't paint going on the car instead of primer. I'm going to plan on spraying another coat of 2K but taking better precautions this time and see what happens :thumbup:
 

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Brian Martin,Freelance adviser
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I think Bob and Crash are right. But again, the "Real" wax and grease removers I listed ARE "mineral spirits" so application could be at fault here.

Using a faster wax and grease remover could have saved you. But wiping it off dry faster could have done the same thing. Leaving it longer to flash could have done the same thing.

Mineral Spirits is a VERY heavy solvent. If the air is full of moisture, if it is cold, if you left it real wet, they are going to take a while to get out. And if it is real high humidity I have seen it do some very strange stuff like NEVER leave, leaving a 2K primer (where it was used as a reducer) WET and uncured days later, even with heat!

Did you wipe it on real wet and not wipe if off fast?

Brian
 

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Discussion Starter · #17 ·
I didn't wipe it on REAL wet but you could see it on the car. I think it was just painters error. Like someone said if I had let it flash a bit longer it most likely wouldn't have done that. It's my own stupid fault :mad: Live and learn I guess :thumbup:
 

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Brian Martin,Freelance adviser
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STATUTORY GRAPE said:
I didn't wipe it on REAL wet but you could see it on the car. I think it was just painters error. Like someone said if I had let it flash a bit longer it most likely wouldn't have done that. It's my own stupid fault :mad: Live and learn I guess :thumbup:
Sorry - I gotta ask more about your application technique...are you using a single wipe and letting the material air dry?

- or -

are you doing it the correct Karate Kid way..."wipe on, wipe off?"

I was always taught to use 2 wipes...1 wet to clean a smaller area and 1 clean dry to immediately wipe any residue off before the cleaner dries.
 
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