Frosty clear coat

[D.Pack]

Hey all.

Some advice please on how to complete this rattlecan clear.

I used Humbrol semi-gloss acrylic, but I have read that humidity could be a cause of this frosted surface.

It's possible, as at time of spraying it was a warm humid afternoon. Damage is done now, but how to fix or at least improve it?

Rubbing compound to remove or will another clearcoat hide all this mess? 

[Ace-Garageguy]

Hard to be absolutely certain, but it looks like what those of us in the real-car paint biz call "solvent popping", usually caused by hammering wet coats when the temp and humidity are both high.

It's an entirely different phenomenon from the "blushing" most often encountered under high humidity conditions.

Blushing will most always polish off, as it's on the surface.

Solvent popping won't, as it's bubbles trapped in the clear.

Try to polish it, see if it gets better. If it doesn't it's "solvent popped" and removing it is the only solution.

Frustrating, yes...but I've had it happen a couple times on real cars. You want to talk about frustrating...  

 

Edited June 20, 2023 by Ace-Garageguy

[bobthehobbyguy]

Interesting info Bill. I've never heard that term before.

[D.Pack]

Thanks to reply.

Heavy wet coats, those small Humbrol cans really blast out the contents and the dried surface, I can even catch my fingernail on it.

Definitely more extreme than the blooming I've had when tried spraying in too cold weather.

Already tried some sanding, does improve the finish. So now to sand the whole car! 

My Slixx nascars are jinxed am sure! Even when the decals lay down, the final step always fails. On another bodyshell, even had paint cracking due to a Microsol solution reaction.

[Dave G.]

19 hours ago, bobthehobbyguy said:

Interesting info Bill. I've never heard that term before.

When acrylic enamels hit the scene I had a go with solvent popping in 1/1. In that case it's thousands of almost microscopic pin holes in the surface of the paint. Coming from Alkyd enamels where this was very rare due to the slow cure, acrylic enamels skin up faster than the solvents can escape, when they do they leave this effect behind. And when I say when they do, I mean in the time it takes to continue on to the next coat, so not long in our time. The answer is two fold, a reducer that slows the actual paint dry time initially and not painting on a hose job lol !! At that point in time it was common to shoot at a suggested 65 psi and high flow rate from the siphon guns, it was too much at least with my Devillbiss. Also they came out with medium dry and slower dry reducers for acrylic enamels. I believe in the Dupont line the one I used was #8022 ( I could be wrong, this was decades ago now but I bought it in 5 gal pales, using several a year). A lot of people tried to use lacquer thinner in acrylic enamel, didn't work it was dull city and brittle finish to do that.

The second phenomenon that took place with acrylic enamels was drying with a slight haze in the gloss. This wasn't about hot humid days though, it was just there.  For this they came out with and I used the high gloss hardener for overall refinishing. This is where the whole suiting up thing and pressurized head piece came in that I mentioned in another thread because now you had a two part paint containing isocyanates. In my case I was all set for that because the other line we shot was Imron which has to have the hardener to cure. In fact Imron came one quart short on a gallon because you put in a quart of hardener, which was thin as water so you didn't need to reduce very much.

Acrylic lacquers can do the solvent popping as well, where nitrocellulose lacquer was about impossible to get to do it. Nitro lacquer is a dream to work with but it doesn't hold up so well out in the elements compared with todays paints.

Anyway, had to chime in on my experience with solvent popping. I think Ace and myself one time before are the only ones to ever bring this up in the forum ! You don't hear the term often these days.

[ctruss53]

WOW that is pretty crazy.

Ace probably has the best advice.

Good luck.

[70mach1]

That is not solvent popping. its  flattening compound that isn't properly blended into the carrier film or defective. those specs are too uniform.  solvent popping tends to gather in low spots or panel edges or paint runs. in short you have a bad can of paint.

[Ace-Garageguy]

17 minutes ago, 70mach1 said:

That is not solvent popping. its  flattening compound that isn't properly blended into the carrier film or defective. those specs are too uniform.  solvent popping tends to gather in low spots or panel edges or paint runs. in short you have a bad can of paint.

Just out of curiosity, how many real cars have you painted?

[70mach1]

Probably a few hundred, my first was in 1969 at a Lincoln Mercury dealership , a few independent shops ending with my restoration and. collision shop. I've pretty much have seen it all

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Ace-Garageguy]

3 hours ago, 70mach1 said:

Probably a few hundred, my first was in 1969 at a Lincoln Mercury dealership , a few independent shops ending with my restoration and. collision shop. I've pretty much have seen it all

OK then. We have similar experience.

And while I agree that popping does tend to be worse in areas of material concentration, I HAVE seen it just as uniform as the OP's example. So uniform it looked like the clear was contaminated with metallic particles...which was a physical impossibility.

The job was a front-end hit on a factory-built Superformance 427 Cobra replica, on which I did all the fiberglass repair and bodywork prior to the paint as well. The temperature was in the 90s, the humidity was in the 90s, and the clear appeared glossy...but like there were uniform silver flakes in it.

I'd never seen anything quite like that before. Careful examination of the surface under very bright light and magnification showed what still looked like particles in the clear.

Sanding the surface exposed the real problem, as subsequent post-sanding examination under magnification showed tiny pits where the surface of the entrapped bubbles had been sanded off.

I had to sand off all the clear, respray the base with a much longer blend, and re-clear 1/3 of the car with a slower hardener and reducer in the clear.

It popped all over, again.

Sanded it off one more time, re-shot the base blended back even farther, and shot almost 1/2 of the car with the slowest clear mix I could come up with at 4:00 in the morning to avoid the heat...and that time it was OK.

Still, without in-person examination of the OP's problem, under magnification, I would never say absolutely "this is what it is...or is not".

You will note I said "Hard to be absolutely certain, but it looks like..."    

 

Edited June 21, 2023 by Ace-Garageguy
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