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Ranthane problems

aflyer

FRIEND
SW Colorado
After much consternation, and googling, I decided to go with Ranthane on my Cubcrafters EX-3 (instead of the PPG fleet paint that CC uses).

Yesterday I painted my test panel, and then again this morning.

It looks nice, and shiney, and smooth, but there are tiny air bubbles in the paint, hundreds of them in a 3x3 foot panel.

Any ideas out there?

Thanks, John
 
More details...I sprayed PolySpray on this panel 6 weeks ago. Temp was about 65 in my hangar.
 
Just an uneducated guess: Maybe sprayed on too thick so that it skinned over while still trying to out-gas??
 
Sounds like solvent pop- do these bubbles actually affect the surface of the paint, as in producing any texture, or are they so tiny you can’t see them except very close and in the right glare? Assuming you mixed pet directions; how many coats and time between coats?
 
That to me is a contamination from the underside, either a cleaner that left a film or something like that which is not compatible with the Ranthane.
 
Not sure what your specific problem is but can offer a couple ideas. I have found that depending on temp and humidity ( Higher is harder to work) Ranthane, Superthane, Aerothane all have to be put on in light coats at first with a good set up time before recoating (tacky on a rubber glove but not coloring the glove). This time is often more than the product recommendation. I also tend to reduce urethanes more that most do. Almost always at least 40% and even higher in very warm and humid conditions. At this point you really have to make a pretty fast application. To get the desired final finish may require an additional coat. ( But you are not actually putting on more paint you are just using less during the first couple coats). I think most problems with the above paints is applying it too heavily and too fast. My 2 cents. Reid
 
That to me is a contamination from the underside, either a cleaner that left a film or something like that which is not compatible with the Ranthane.
That would more commonly result in a series of fisheyes where the paint “pulled back” and uncovered contamination, not what i would typically call bubbles- maybe we need a pic if a camera can capture it?
 
Thanks for your replys. The bubbles are tiny, maybe .010 across or less. I can feel them if I run my hand over them. Maybe I will try thinning it more, and then the bubbles would pop. I will try to take a picture tomorrow.
It may be too thick. The directions say "two medium coats" but as a beginner, I don't really know what medium is.
 
Certainly not an expert but are the bubbles uniform across the surface, or does the concentration of bubbles vary? If they are uniform, then that could be paint, if not uniform, them possible surface contamination.

Also, how did you clean the Poly Spray prior to paint?
 
surface or air supply contamination, we can only offer suggestions as to cause. its not the paint
 
Pictures would really help. It kinda sounds like solvent trapping to me. How dry was it when you layed the next coat down? ALL polyurethanes have to be to about the same "stage" before they're ready for another coat.... sticky like fly paper, but no transfer to your finger. Some have a more generous window of time that they remain this way. The limited amount of Ranthane I sprayed seemed to be pretty nice, but high solids as stated before, so you have to watch to not get too much on at a time.
John
 
Thanks again for your replies. The gun is an HVLP with a turbine type compressor. They are supposed to be oil free, and it is really dry here now. I tried to take pictures today but even I can't see anything in them. I knew I was supposed to wait for "tacky" for the second coat, but then the power went out for a couple of hours, and it was pretty dry when I got back to it.

I am going to do some experiments, and talk to the PolyFiber people tomorrow. It could easily be that I am doing it wrong. I feel fortunate that I haven't painted any of the airplane yet.

John
 
Ranthane isn't usually used oner Polyspray, is it? It's normally a top coat over butyrate? Would that make a difference? Aerothane is the urethane top coat for poly. Much thinner. How did you come to choose Ranthane?
 
Ranthane and aerothane are both approved and commonly used over the stits system. I think Steve P. shoots quite a bit of it over poly spray and I have as well.
 
Ranthane and aerothane are both approved and commonly used over the stits system. I think Steve P. shoots quite a bit of it over poly spray and I have as well.
That is correct. And many prefer to use the ranthane because with the heavier solids it is easier to spray without runs that aerothane. Both work very well over poly spray if the surface is clean and prepped properly.
 
Solvent pop. Not allowing the paint to “gas off” before putting the next coat on. Probably looked perfect when you set the gun down. I have a hard time with solvent pop cause i tend to be in a hurry when paining. I have to set a timer on my phone and walk away, get a ice tea, relax and impatiently wait for alarm to go off.
Then go spray next coat and start process all over again. Unfortunately I’ve had very little luck with color sand and buff. Take your time and it will come out great. My Maule has Ranthane on it.
 
Solvent pop. Not allowing the paint to “gas off” before putting the next coat on. Probably looked perfect when you set the gun down. I have a hard time with solvent pop cause i tend to be in a hurry when paining. I have to set a timer on my phone and walk away, get a ice tea, relax and impatiently wait for alarm to go off.
Then go spray next coat and start process all over again. Unfortunately I’ve had very little luck with color sand and buff. Take your time and it will come out great. My Maule has Ranthane on it.

Actually, just the opposite. It was full of bubbles at first, then most of them went away in the first 10 minutes. A hundred or so stayed on a 3x3 panel. I put a second coat over it the next day (after the power came back on), and the bubbles happened again. That makes me doubtful that it was due to an unclean surface. Both were thick coats though, so that will be one of my experiments.
 
I’m assuming you used all ranthane products. If that’s true then it sounds like contamination from; what the gun was cleaned with last time, air source or on the surface.

if you used a diff mfg thinner or activator it could also be the problem.
 
Yesterday I talked to the technical help line at Polyfiber, and was referred to a fellow named Waldo, who does restorations and sprays a lot of Ranthane. We discussed what I was doing, and his conclusion was that I was not applying the paint thick enough.
He does one light coat, then two heavier coats, 30 minutes apart.
I am building two more test panels so I can experiment with different amounts of thinner. I will report back if I learn anything.
John
 
Also I would not use Polyfiber's paint cleaning solvent, I have had what you describe that I have not had since I quit using it. I have seen it still out gassing 2 hours after I prepped. I use isopropyl alcohol sprayed on a rag and that to wipe the surface down. I shoot a lot of Ranthane and shoot a tack coat, spray my wet coat when the tack coat doesn't come off on my glove and the second wet coat the same. Waldo knows his stuff, have talked to him several times.
 
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