Pop fix
 

Hey guys,
Got a problem I'm sure most of you have seen. I have really tiny bubbles deep in my clear coat. Research tells me this is solvent pop. The surface is nice and clear, smooth no cratering and the paint has set up for a couple weeks now. I noticed this when I was compounding the parts after wet sanding. Other than the bubbles everything looks good. I let the Chroma base set up overnight and probably rushed the SPI universal clear a bit.
These are just small parts, emblems and tail lights and such. My question is could I just wet sand now with like 400 and re-base and re-clear. Like I said the parts have been sitting for a couple weeks and the surface is all buffed out and smooth. No wax just compound. If not what's next???
Thanx for your time and effort
Steve

If you have enough clear to sand them out do that. If not sand them all the way out and apply another base coat then clear. Solvent pop usually comes from rushing coats of clear. If you have enough clear to sand them out place the part or the car in the sun for an entire day then reclear. You want to give the sanded clear plenty of time to off gas before putting fresh clear over it. Here is a picture of a solvent pop problem I experienced when painting my 34.

http://www.hotrodders.com/gallery/da...m/DSC00592.JPG
Vince

Where the pops there right away or did they show up after a couple of days? How big are the "pops"? and are they raised? If they are solvent pops, as 302z28 said, block sand them out and re-clear as he mentioned. The only time you would need to re-base is if you burned through in trying to get rid of the pop.

If you can answer the top three questions, I can determine exactly what they are and offer solutions.

Ray

When I ran into this issue on the rear fender of my 34 it had been cleared for several weeks and there was a flaw I needed to correct. I wet sanded the entire fender then applied fresh clear. Several hours later the solvent pop appeared. BarryK of this forum told me of my mistake and how to correct it. When I wet sanded the existing clear it opened up the surface and allowed it to gas off. When I applied fresh clear almost immediatly that is what caused the solvent pop. By placing the part in the sun for an entire day after the pop had been sanded out allowed the trapped gasses to vent completely then new clear could be applied without the solvent pop.

Vince

Good advice Vince...and yes trapped solvents do need to be released before applying any new product...after a panel has been sanded with problems such as this, you can actually smell the solvents still in the paint...Very good advice to let it sit after sanding.

Ray

pop
 

I had a buddy that used the same clear on a complete had the same problem he didnt want to take any chances since it was the first time he used this clear on a customers car and didnt take any more chances and sanded the car down and recleared it with what he always used transtar euro clear. Sounds like spi is great stuff once you learn to use it properly.

Since I have been on this site I have heard so many good things about SPI, I would love to try some but I don't think we can get it in Canada...maybe one day.

They dont ship it to canada ? I have heard lots of good things about there product as well only thing bad is about that clear solvent popping that barry k guy that posts on here is a big wig with spi talk to him 69 wide track

Thanks "diggers" for the information...in Canada we now have nationwide VOC laws that came into effect in January of 2011 that if the paint material doesn't meet federal standards with regards to the amount of VOC's in the product it's not legal to sell it...if you have it, you can spray it but, if you have it and want to sell it in Canada it's illegal. I don't know if SPI meets the Canadian VOC regulations.

Thanx for the response Ray. Look'n back here's what I think happened. I shot the first coat of clear on a cool dry morning with medium activator, outside. It seemed to be taking a loooong time to flash. I waited a good hour and still "runny" The sun started to come out and the clear started to "firm" up. I then shot the second coat kind of heavy. Now I have too much sun and the second coat flashed up like normal but with these tiny bubbles on the parts exposed to the sun.
To answer your questions, yes some were there pretty quickly some "developed" over time. They are so small I could not see most of them when I compounded the clear in my garage under florescent lights. When I took the parts outside in the sun, to check for color match that is when I seen the extent of them. The surface is like glass. Smooth, shiny and hard. I was going outside looking install these trim pieces, they look that good....cept for the bubbles. I wet sanded the parts about a week after painting and then compounded about a week after that. I know not to rush those steps as you can cause the same solvent problems by sealing fresh paint with wax. No wax has been applied just compound.
Thanx for your help.

Yes, the way you explained how, when and under the conditions the vehicle was cleared, you have a recipe for "solvent popping", especially with a little breeze and the sun warming up...Basically what happened is, cool temperature, but constantly getting warmer, the clear starts to cure but, the top of the clear (being in the sun and warming up) skins over. Underneath the skin is clear that still has solvents in it. In order to get chemical adhesion, these solvents travel down to the metal drawing the active component molecules of the product down with it. These molecules lock into the sand scratches (mechanical adhesion) and the molecules of your substrate (primer, existing paint whatever = chemical adhesion). When the solvents hit the metal they bounce upwards trying to escape, completing the curing cycle. The problem is they have a hard time escaping because the top of the clear that was just applied has skinned over. They build up like a volcano and eventually POP. That's why they call it "solvent popping".

Not that this explanation is going to make your repair easier, hopefully it will help you understand a little the chemistry and the reaction these chemicals have when conditions either change or a "perfect storm" is created. In your case, you had a bit of both.

I mentioned in one of my previous posts how to repair your situation...If you need more information or have questions, just ask and I'll try and help.

Good Luck
Ray