Airbrushing polyurethane?

[Foamforce]

Anybody tried thinning oil based polyurethane with mineral spirits and spraying it on with an airbrush? I’m talking about waterproofing, rather than brushing it on and wiping it off. I’ve read that wood workers sometimes use airbrushes to apply poly on small projects. I’m interested in it because it seems like it would be faster and more thorough than brushing and wiping and it would leave a more even coat.

 

[Inq]

Anybody tried thinning oil based polyurethane with mineral spirits and spraying it on with an airbrush? I’m talking about waterproofing, rather than brushing it on and wiping it off. I’ve read that wood workers sometimes use airbrushes to apply poly on small projects. I’m interested in it because it seems like it would be faster and more thorough than brushing and wiping and it would leave a more even coat.

I once did it on a larger scale... on a cedar plank kayak. Long time ago, but I think I cut it with isopropyl alcohol. But, I may be miss-remembering cutting epoxy with the alcohol. Anyway, I think you need a good quality carbon filter respirator. Those particles in the air... can do a number on your lungs.

 

[Foamforce]

Absolutely beautiful! And yes, I need some good ventilation and a respirator.

Did you use an airbrush or a full size paint gun on that?

 

[FlyingWithRyan]

If you really want to airbrush it I'd recommend a siphon fed airbrush, it'll be easier to clean than a standard gravity fed.

 

[Inq]

Did you use an airbrush or a full size paint gun on that?

... That'd be like watching paint dry golf. No, I used this. Occasionally it goes on sale for $9.99. I'm assuming it's just a matter of scale and air-brushing pen would work the same... just make sure you get it cleaned out fast. It dries very quickly when atomized.

 

[Foamforce]

If you really want to airbrush it I'd recommend a siphon fed airbrush, it'll be easier to clean than a standard gravity fed.

I recently got a set with both styles and have started playing around with them. Why is the gravity feed easier to clean? I’d probably try siphon anyways, just because I’d be covering a lot of area and I don’t want to refill that much, but I’m curious.

 

[luvmy40]

I recently got a set with both styles and have started playing around with them. Why is the gravity feed easier to clean? I’d probably try siphon anyways, just because I’d be covering a lot of area and I don’t want to refill that much, but I’m curious.

He said the siphon fed (atomizer) would be easier to clean.

 

[Bricks]

If covering a large area an HVLP like pictured is the way to go, faster and easier to get an even coat. Me personally would never try and spray a good sized air frame with an airbrush many do but I am not one of them..

Cleaning and HVLP pretty simple I use Lacquer thinner, empty cup add some Lacquer thinner shake with thumb over vent hole in cap this will build a little pressure in the cup. With thumb still over vent work the trigger to empty the cup , do it again then put lacquer thinner again in cup and wipe out with a paper towel being sure to wipe the nozzle area good with the soaked paper towel pulling trigger to empty cup and done..

 

[FlyingWithRyan]

I recently got a set with both styles and have started playing around with them. Why is the gravity feed easier to clean? I’d probably try siphon anyways, just because I’d be covering a lot of area and I don’t want to refill that much, but I’m curious.

Yeah the siphon fed is easier to clean. Theres less nooks and crannies in the atomizing tip and they can all be easily disassembled and soaked in solvent to remove the urethane.

 

[TimothyHall]

Anybody tried thinning oil based polyurethane with mineral spirits and spraying it on with an airbrush? I’m talking about waterproofing, rather than brushing it on and wiping it off. I’ve read that wood workers sometimes use airbrushes to apply poly on small projects. I’m interested in it because it seems like it would be faster and more thorough than brushing and wiping and it would leave a more even coat. four in a row

Anybody tried thinning oil based polyurethane with mineral spirits and spraying it on with an airbrush? I’m talking about waterproofing, rather than brushing it on and wiping it off. I’ve read that wood workers sometimes use airbrushes to apply poly on small projects. I’m interested in it because it seems like it would be faster and more thorough than brushing and wiping and it would leave a more even coat.

 

[Inq]

Anybody tried thinning oil based polyurethane with mineral spirits and spraying it on with an airbrush? I’m talking about waterproofing, rather than brushing it on and wiping it off. I’ve read that wood workers sometimes use airbrushes to apply poly on small projects. I’m interested in it because it seems like it would be faster and more thorough than brushing and wiping and it would leave a more even coat.

It was a long time ago, but I used oil based poly on the boat above. But if you just want waterproofing, the water based poly once dry is waterproof. It's what was used on my wood floors and its held up longer than the previous oil based poly that was stripped off.

 

[FlyingWithRyan]

It was a long time ago, but I used oil based poly on the boat above. But if you just want waterproofing, the water based poly once dry is waterproof. It's what was used on my wood floors and its held up longer than the previous oil based poly that was stripped off.

I've found anything water based dissolves the glue they use to stick the paper to the foam board, it must be like a water based glue like pva or something.

 

[Foamforce]

Coincidentally, last week I tried spraying oil based poly, thinned with 20% mineral spirits, using the cheap Harbor Freight spray gun that @Inq suggested. It was a fairly even coat, despite spraying outside with poor light and low temperatures. It was nicer looking than when I brushed it on. I haven’t tested how waterproofed it is yet but it looks good so far.

 

[FlyingWithRyan]

Coincidentally, last week I tried spraying oil based poly, thinned with 20% mineral spirits, using the cheap Harbor Freight spray gun that @Inq suggested. It was a fairly even coat, despite spraying outside with poor light and low temperatures. It was nicer looking than when I brushed it on. I haven’t tested how waterproofed it is yet but it looks good so far.

Is the verdict out on what they use on the FT foam board to waterproof it? Feels almost like a wax or something

 

[danskis]

Adams doesn't use glue to attach paper to their dollar tree foam. I don't know about the FT foamboard.

 

[Inq]

I've found anything water based dissolves the glue they use to stick the paper to the foam board, it must be like a water based glue like pva or something.

You are definitely right. I was mixing usages badly. For home wood working projects, I use the water based version. On a family table top and hard-wood flooring or even a boat, I found it lasted longer (never re-done) versus oil based needing to be redone on the floor. It was completely waterproof after finishing. I prefer Varathane Crystal Clear for that. For foam board it was a disaster. I use the oil-based Minwax as suggested on this thread!

 

[danskis]

Adams doesn't use glue to attach the paper to the foam...its just pressed on during the process. Interesting history of foanboard and how its made.

https://www.rcgroups.com/forums/showthread.php?1533245-Model-Plane-Foam-the-Story-and-Product

 

[Inq]

Adams doesn't use glue to attach the paper to the foam...its just pressed on during the process.

As this is a repeated comment, I'm assuming it is somehow related to what I just wrote. I might have missed your point. Regardless of how the paper is attached on DT foam, it still wrinkles with the water-based, but doesn't with the oil based. I tried it with my on-hand Varathane. I didn't want to buy the expensive Minwax just for foam planes when I have a gallon of the Varathane. Varathane trashed my plane. I broke down and bought the Minwax! No issues except hot-glue doesn't stick worth a flip to it.

 

[danskis]

Thanks - Good to know about the hot was not sticking. I always put the minwax on before gluing.

 

[Inq]

Thanks - Good to know about the hot was not sticking. I always put the minwax on before gluing.

You found a way to make hot-glue stick to minwax??? I even roughen up the dry poly with sandpaper. Part fell off in first flight. Good thing it wasn't the horizontal stabilizer. Maybe, my hot-glue is for crap? I tried Walmart brand and Gorilla Glue brand. Both didn't stick for me.