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Building Tips and technical articles. => Building techniques => Topic started by: Clint Ormosen on July 03, 2008, 10:09:08 PM
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I had this problem while painting the Chipmunk and now with the Mustang as well. I started with a nice smooth surface. After the white base coat it was still pretty smooth. Then, two coats of red and you could see a little texture to it. Now the clear. With each sucsessive coat it gets more and more Orange peel in it. I have 4 coats of clear on it and it's starting to look like 80 grit sandpaper. I shot one coat of 90% thinner trying to smooth it out but it did nothing. I've tried adding a little retarder, also no effect. It's hot outside even in the evening. Been shooting in about 90 deg weather.
Ideas?
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First things firts, what paint are you spraying and most important, what thinner are you using.
what spray gun are you using and how much airpressure?
these things all affect the results when you are spraying so they are important. but in the interest of giving you a direction to look you may try some of these things,,
You could try narrowing the fan control on your spray gun this will put out more material in a smaller area thus keeping it wetter on the surface allowing it to flow out better. try reducing your paint a bit more, maybe another ten percent or so. Try a slower thinner. depending on what pressure you are using, try a lower pressure. You mention you had the same problem with the chipmunk and I assume it was not quite as hot when you painted it. This leads me to feel that perhaps your technique or material is not quite right.
Bottom line, when you get orange peel what is happening is that the material is not getting to the surface with enough solvent remaining to allow it to flow, or there is not enough material getting to the surface to begin with. as long as you are through all the color and spraying clear, you could sand the clear with 600 on a soft block, then reaply more clear with slower reducer, less air, gun closer to the surface, move the gun slower or add more solvent to the clear before you spray.
standard disclaimer, ALWAYS use the thinner designed by the paint manufacture for the paint you are spraying. I know lots of people say you CAN do this or that, and they are right, sometimes it will work, but the one time it doesnt you will hate them, the paint, the plane, and yourself..!!!
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All the stuff Mark said. Generally when I get this (and believe me, I get this), it's due to not enough thinner in the mix and/or too low a pressure. But as Mark says, it depends on what you're shooting.
As he says, "First things firts". I had a firt once...
OK, I think I'll go back to playing my computer game.
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I'm spraying Brodak color dopes and Randolph clear using Randolph Thinner. I've tried different pressures from 15 psi to 40 psi. Tried different fan patterns too, no change. The gun I'm using for clear has a 1.4 nozzle. The color gun has a 1.0. Finex guns.
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Clint,
Then it seems that you haven't thinned it enough. I'd cut it another 10% and see what you get. Just don't go too heavy and you should be fine.
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Randy,
Was your recent surgery to remove your firt?
Will
P.S. Hope you're feelin' better! :-[
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Thanks for the tips. Would it help at all if I switched spray guns to the smaller one with the 1.0 nozzle in it?
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Will,
Nope. It was a, uh, lifting related accident. Or as my surgeon said, hey man, you ain't 25 anymore.
I spent the whole day trying to get a new computer that I just assembled to work. Turns out it has a bad motherboard (man, I will never by an ECS motherboard again. Think I would have learned on the first one).
But I did have time to go out an put fillets on the new ship. ;D
Clint,
Ty is right. I'd just thin the stuff until it flows. Whoops, I think I already said that.
The 1.4 is probably fine with enough pressure. Guys use that size to shoot clear on cars all the time.
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Clint,
So, how's it look now?
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I thinned a bunch and shot one final coat. Now this has happened! That's the white undercoat showing through. And it's going to stay that way too because I have no intention of sanding it all down and reshooting it.
So now I'm confused and ticked off. ''
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You're not alone. I looked at a brand new Corvette in the showroom the other day. The horizontal surfaces were superb. The doors and fenders showed significant orange peel in the color layer, but the clear overcoat leveled it out so is still shined up nice. Too bad we can't use 25 mils of paint!
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Clint,
Congradulations. You've come up with something I've never seen before. Wow.
Not crap in the gun, I take it?
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No crap in the gun. No fish eye killer. No engines ran within a mile of the plane. No water in my air tank. Silkspan covered. Nothing different at all. Just decided to open a bunch of little holes. There is a few more spots on it but that pic shows the worst area.
However, after sanding out the nose, it's buffing out real nice. Just going to be a lot of work.
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Clint,
I've had this happen also. Usually because the surface wasn't clean enough. I've taken to using nitrile gloves whenever I handle the plane after primer is sanded. I clean the plane really well then just used gloves. And I have still occasionally gotten pinholes. They usually sand out fine, but it is a pain. And as Ty noted, they can also be cause by shooting primarily in hot weather where the paint starts to gas actively and the paint dries too quickly, before it can lay out. Slower thinners (or hardeners for polyurethanes) and a wetter coat usually takes care of it. Usually.
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I thinned a bunch and shot one final coat. Now this has happened! That's the white undercoat showing through. And it's going to stay that way too because I have no intention of sanding it all down and reshooting it.
So now I'm confused and ticked off. ''
What you have experinced is solvent pop.
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What you have experinced is splvent pop.
Or better know in the collision repair world as "solvent pop" :D Huh Sparky.
Jim Snelson
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As Roberty said, It could well be solvent popping. What happens is that somewhere in the process the paint flashs off on the surface to fast and there is a large amount of solvent trapped below the surface "skin". then the trpped solvent has to get out so it forms bubbles and breaks through the surface. If the white is actually showing through it would lead me to beleive that the solvent was trapped in the red layer. However, with laquers inherant properties, that being, fresh solvents basically have to penetrate to the core then come back out,, it could have been in the last coat of clear. If you use to fast of solvent and to high a temperature, the clear will skin over and solvent popping will occur. It really sucks, been there on a car a time or two. The other contributing factor is if you really pound a coat of material on there is excess solvent to escape.
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I've heard of solvent pop, but never seen it. Of course, when you're shooting paint in 50-60 degree temps and relatively high humidity, I don't suppose you would. As Alan Resinger told me at the Regionals this year, it's amazing sometimes, you can do everything right and still have it go into the toilet. Probably why painting is still as much art as science.
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OK thanks. At least I know what it is and what probably caused it. I'll try not to spray in such hot weather from now on. I'm sure it can be done, but I'm not enough of an "artist" to pull it off just yet.
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Clint,
No, you just need to get the thinner for the conditions. There are thinners designed for high temps (well, 80-90, not much above that). One of the issues with lacquer is, there are a lot of things that can go wrong. They don't happen often, but they happen. Sigh... Sorry the thing has been a pain.