URETHANE PAINTING

[John Parker]

Seems I probably will spray my new cover job with Ranthane . And my knowlege of spraying urethane is feets below sea level .

Need to know if there a safe respirator out there other than the HVLP turbine air supply unit. And a reccomendation on a non HVLP spray gun if one is needed to spay urethane.

Thanks

I would sure appreciate your experience / comments.

John P.

[Nathan K. Hammond]

Shooting Urethane's isn’t really "hard", it just takes technique.

The first thing to do is paper a wall, and spray it for practice. Learn how the gun patterns, and reacts to your movements. Learn how much it takes to run or sag the paint and get a good feel for it. Learn what too much psi at the gun looks like, and what under thinning does. When you're spraying, you want a good overlap, some like half, I try for about 2/3.

After you've prepped the panel (wiped with alcohol, and tacked off) shoot the first pass really, REALLY thin. Just enough to make a color change. If you pile it on, it will run off on the floor. When that first mist coat is tacky, shoot a nice wet looking coat. One final wet coat, sprayed into the tacky wet coat should do it. That makes a total of 3 coats, remember paint is heavy, no need to put more on than what's needed. When spraying white, sometimes it may take an extra coat to get good coverage, make that call when needed. It's important to shoot into tacky paint, that's what holds the next coat on. If you flood the paint on, or spray onto a dry surface, it will literally run onto the floor. If you spray a coat, let it dry, and then realize it needs another, wait about 3-4 days to cure enough for sanding, then go over it with a red Scotch-Bright pad.

Guns: They make really good HVLP guns that use compressed air, so the need for a turbine unit isn't mandatory. Go ahead and buy a good gun, no point in chancing the paint job to save $100. I went down to the auto paint store and found a really good deal on a Sharp 2 gun HVLP kit for about $350, and haven't regretted it. Sharp, Devilbiss, Binks; they're all good, and anywhere from $100-$500, just find one you like. They all make top and bottom feed guns, there's no difference in how they shoot, but some people like one better than the other. Get a 1.4 tip, they seem to do the best.

For any urethane spraying, a fresh air system is almost mandatory! It's some pretty harsh stuff, and a regular charcoal mask doesn't cut it. Either buy one of those buddy box system like in Aircraft Spruce, or make some kind of forced fresh air breather your self.

the quick and dirty on painting.

nkh

[John Parker]

Thank you for the good advice here.

John P.

[MikeB]

Good ideas from Nathan....for my part, I ordered the fresh air supply system from Wag Aero, about $350. It works great, I just set the air pump unit outside my shop and run the fresh air hose inside. I have a Sharp gravity flow gun with either a 1.5 or 1.4 mm nozzle (can't remember) Seems to work very well. I used the Super Flite process on both my last two projects, which is poly urethane. It's a bit heavy but looks nice and bright when done. Might be why I only have a 375# useful load (?) I generally cover up real well when I paint, but have been thinking it might not be the worst idea to get a paint hood rather than the fresh air mask to keep out of the paint as much as possible. Urethane is nasty stuff, or so I've been told. Some way of venting the shop is a must, I used a barn fan, but one of the more sealed fan units from Home Depot, etc. might prevent blowing the shop up!! Also, you can't have too much light, but where you put it helps a great deal with the painting process. If it glares too much (white especially) it's hard to lay the paint accurately. A drop light in addition to regular lighting helps sometime. Much fun: dragging a paint gun air supply hose, fresh air hose and a drop light. One further note: I bought an excellent book at Oshkosh.."Eaa presents How to Paint Your Own Airplane by Ron Alexander" and as Nathan says: practice, practice practice. Good luck....Mike.

[Nathan K. Hammond]

One other thing i forgot to mention, ALWAYS use Fine line Polypropylene tape. Masking Tape will bleed through and leave a fuzzy line, trust me, I made that mistake.

http://www.aircraftspruce.com/catalog/c ... netape.php

nkh

[shorty]

Seems I probably will spray my new cover job with Ranthane . And my knowlege of spraying urethane is feets below sea level .

Need to know if there a safe respirator out there other than the HVLP turbine air supply unit. And a reccomendation on a non HVLP spray gun if one is needed to spay urethane.

Thanks

I would sure appreciate your experience / comments.

John P.

I'll garontee that you can't go wrong with an "accuspray" gun and a good 3 stage turbine. As for breathable air, I use a DeVelbiss filter system with a SATA mask, Total cost is about $1200, for the mask and filter system, Good clean air from a standard compressor.
You can buy a decent gravity feed gun from Home Depot, but it dosen't hold enough material for an airplane. The best way to go is with a pressure pot, which holds at least a gallon. And then to paint in sections instead of trying to paint the whole thing all at once. ie; paint the wings, then paint the fuselage, then paint the control surfaces.

[shorty]

One other thing i forgot to mention, ALWAYS use Fine line Polypropylene tape. Masking Tape will bleed through and leave a fuzzy line, trust me, I made that mistake.

http://www.aircraftspruce.com/catalog/c ... netape.php

nkh

If ya gotta have a roll of tape, It ain't ready to paint! LOL
Yes for stripes and numbers, I would reccomend using 3M "fineline" BLUE. As it leaves a nice clean line, and turns corners nicely. It's a rubbery/plastic tape. easy to work with, and is better than the green tape.