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Building Tips and technical articles. => Paint and finishing => Topic started by: James Mills on April 03, 2010, 08:14:56 PM
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I sprayed the clear on my Tempest this afternoon, 4-1 clear. After the second coat it looked good, nice shine. After an hour or so it looked more satin (I guess orange peel some). Did I do something wrong in spraying or is this normal? I was using an HVLP gun set about 20 lbs.
James
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Could have been temp. If it orange peeled, either the mixture was too thick for the air temp or your pressure was too low. Not a tragedy. You can always sand it and rub it up.
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Be sure it was clear GLOSS not clear SATIN.
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Could have been temp. If it orange peeled, either the mixture was too thick for the air temp or your pressure was too low. Not a tragedy. You can always sand it and rub it up.
Randy,
It was dry and around 70 degrees. I was running only 20 pounds, maybe next time crank it up some more.
Thanks,
James
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Be sure it was clear GLOSS not clear SATIN.
Good point, it is gloss.
James
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James,
there are only a couple reasons that urethane clear goes satan, the first is not enough dry time between coats, trapping solvents.
couple questions, is the entire surface of the airframe satin, or just certain parts?
if just parts are, which parts, the upper surfaces?
Did you maintain any airflow through the room you sprayed in after you were done, one thing that can happen with urethanes when you dont maintain airflow, the microscopic reducer and clear molecules that float around in the air will settle back on the surface causeing a stippled, or satin looking finish.
another thing, what solvent did you use? I would have used the absolute slowest solvent available, hmm ok wait, you were using a non reduceing clear. Ok that being said, what catalyst, generally there are several catalysts available to compensate for different temperatures.
If it was glossy when you finished shooting it, and the surface was smooth with no real orange peal, then I would say that you probably were ok on air pressure. UNLESS you totally flooded the surface with clear, but then you would typically have some runs somewhere on the plane..
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>>If it was glossy when you finished shooting it, and the surface was smooth with no real orange peal<<
Yea, I missed this the first time. Mark, you'd know better than me. I've never had a problem where orange peel showed up after the fact.
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Randy, my interpretation wasnt of orange peal after it dried, more like die back from trapped solvents. more like the gloss hazes away,, perhaps James can clarify to make sure we are addressing the correct issue?
My suspeicion is that the solvents from the clear penetrated the laquer base, it kind of hid there until the urethane flashed over, then it had nowhere to go. Its like a really bad case of solvent popping,,
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Randy, my interpretation wasn't of orange peal after it dried, more like die back from trapped solvents. more like the gloss hazes away,, perhaps James can clarify to make sure we are addressing the correct issue?
My suspicion is that the solvents from the clear penetrated the lacquer base, it kind of hid there until the urethane flashed over, then it had nowhere to go. Its like a really bad case of solvent popping,,
Solvent popping sounds scary. What I'm calling orange peel is it looked somewhat glossy and (then after it dried) had a bumpy look as well as gloss. I've wet sanded some of the small parts and it seemed to buff up nice. This plane has been a finishing nightmare. I'll post some pictures when it's in one piece and describe some of the problems I had.
James