I've been painting a 90 mustang for a friend that has a aftermarket fiberglass hood.
I'm using PPG bc/cc Stratoclear urethane..
This paint smells just like Duponts 7800 urethane system. Reduces the same also.
Here's the problem.
The whole car took the primer, filler, and paint just fine except for the damn fiberglass hood. It was in primer with the gelcoat underneath, I sanded it with 400 and used the evercoat urethane primer over it to ensure good color matching between all the parts that I was painting separate as this red is a bit transparent. I used all the same exact materials on the entire car.
But when I shoot the clear it goes on like theres some fine fish eyes. As I add the topcoat they go away. Keep in mind that you have to lay a pretty thick 2 coats on to smooth this out. When I'm done spraying it's as slick as glass. You wouldn't even have to sand it except for the few small nibs here and there. After about 20 minutes during the drying time I start to see these tiny micro bubbles coming up out of the clear. Theres so many of them that it looks like I dry coated the clear, I mean thousands of them.
Well I talked to a few paint reps and told them and they said it was setting up too quick for the temp, so I went with the slowest clear activator for the paint. I wet sanded the hood again with 400 not going down to the base and reshot it. It looked like it was doing the same thing all over. Sure enough, upon the drying time it all came back. But this time not as severe, but still looked like crap. So what gives with this?? The rear spoiler also did a little bit of this, but none of the metal or plastic moldings.. It's got to be with the fiberglass parts. But you would think the uroprimer would have sealed all this out.
Since I'm still in my 24 drying window I'm going to shoot another coat of clear without sanding since the bubbles aren't open on top.
You have to look really hard to see this the second time around. I've never encountered this before, and I hate to not know what the cause is. I've never had fiberglass problems before.

Thanx RandyB..
www.angelfire.com/ky2/mycars (http://www.angelfire.com/ky2/mycars)

Randy;

I've had similar problems!

It's as you describe, the bubbles form after the paint has flowed out well and you think everything is good in the world.

What I believe is the problem is a small amount of silicone being present. In your case, my bet would be that it was used as a mold release when they made the fiberglass piece. (in my case, I think that it was in one of the wax products that I used)

Now this is guess work based on what was happening to me; It seems that once in the paint you can't ever get it out! When you spray another coat over the problem paint, it "leaches" out of the lower coat and effects the new coat. It's as if there is no end to it!!!!!

What I'd recommend you try is sand the item down as much as you can and then seal it with DP90. Due to the DP90 being an epoxy sealer, it should prevent any further leaching of the silicone. DON'T SAND THROUGH THE DP90!

Of course, I could be totally wrong.

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Wes. Vann
Technical Reference section
Gold Member #5

I think Wes has it right. Silicone is your enemy here. Did you clean it with a detergent? Then follow that with Prep-Sol? If you didn't, you sanded and spread that silicone thru-out the entire pre-paint procedures. You're going to have to remove some of that paint build up and seal it. Clean at everystep along the way with a pre-paint cleaner and you should be OK. Then again.....I could be totally wrong....... http://www.chevelles.com/forum/biggrin.gif

My hunch is that it is solvent pop. Let me tell you why....
This was my first thought, they come after the clear is on there a few minutes right? Fish eye would be instantly, the clear is not sticking to a contaminant, so it is instant. The solvent pop is trapped solvent that comes up after the top layer drys and the solvent "pops" through the surface like weed coming through asphalt. Now, I thought, but this can't be because you shot the whole thing and it didn't happen on the roof. Then I read your post again, the hood is off the car! It is human nature to put it on a little heavier on the hood, that is what we will be looking at more than anything and we want it smooooooth. Well, there it is, atomize the clear better (go to these two links... http://www.autobodystore.com/cgi-bin/config.pl?read=42586 http://www.autobodystore.com/cgi-bin/config.pl?read=42587 and you will see some things I have posted on gun set up) or just plain don't lay it on so heavy.

The urethane primer probably would have buryed most any fish eye causeing contaminant on the hood, so I will stick with solvent pop.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"

[This message has been edited by MARTINSR (edited 08-26-2001).]

MARTIN I noticed when the clear was going on the very first coat that just as soon as the paint was landing on the hood it was acting funny. Almost like it was trying to fish eye.
What freaks me is that the uroprime didn't show signs of this in the first place. And now that it has been repainted bc/cc again that it's still doing this freaky sh$%. It has to be solvent pop like you described becaust I fixed a few low spots with filler and primed the whole thing. I painted the hatchback separate and it's metal,and it didn't do this. Scratch trying to fix this probelem. I'm already going in the hole. The hood was given to the boy and he didn't really care for it anyway. He's going to order a different hood. I've got enough materials to cover the new hood. I'm giving up on this one so it won't come back to haunt me down the road later costing more money out of my pocket. I was just trying to find out what the cause was as I've never run into this before. I know it wasn't gun set up as I've been painting quit a few years now.

I appreciate the help on this.

RandyB.. www.angelfire.com/ky2/mycars (http://www.angelfire.com/ky2/mycars)

Just got a digital camera so new photos to come soon.

Seems like solvent pop. Fish eye would show up real fast on the first coat.

You have two problems.
The first and biggest problem you are having is solvent popping....due to the fact of using a product not designed to do what you are trying to use it for. The Strato-Clear (DCU 2082) is a spot and panel repair clear only......designed for 1-2 panels....and in the heat of the summer, 2 large panels is pushing is....even with the slowest hardener.
As described in earlier responses....the clear is beginning to set up and the surface is skinning over while solvents are still trapped in the film....Those solvents are going to come out. When they do, they break thru the skinned over surface leaving a micro-blister, or in worse cases, a pinhole.
This almost always only happens on top surfaces, but in extreme cases can happen on side panels as well.

The other problem....the clear spraying funny, like fisheyes right out of the gun, is simply the product not being atomized correctly. As you have noticed, the Strato is some thick stuff, as all paint products these days are. Higher air pressure, along with the right gun setup (1.2-1.3) will allow you to spray the stuff the way it is supposed to look. Also slower solvents will help in this situation as well.

Shannon