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Old Feb 11, 2009, 01:56 PM
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Mod Podge

On a recent trip to the local Michael's craft store, I picked up a container of Mod Podge - "water-based sealer, glue, and finish for all surfaces" for about $6. The label says it can be used for sealing puzzles, decoupage, paper mache, and a host of other craft projects --- sticks to all sorts of surfaces - most notably >>> FOAM! Comes in gloss and satin finishes, plus a variety of specialty formulas for fabric, outdoors, glow-in-the-dark, sparkles, and "hard coat" (which I did not see in stock - but might work even better for planes).

I tried a little last night on one of my planes to see how it works. I have a 90% packing-tape covered FFF wing, but the wingtips are not covered with tape due to their compound curves -- there's jut no way to tape them and make it look nice.

The Mod Podge looks like thick Elmer's white glue, but smells like there might be other ingredients (smells more like wood-glue than white glue). It goes on white, self-levels (somewhat) and dries clear in about 15-20 minutes - cleans up with a wet rag if you need to start over. I used a foam brush to apply the MP and the first coat went on a bit "streaky" (a bristle brush might apply smoother) but leaving the part to dry in a horizonal position helped it to level out. Also, I may have put that first coat on a bit too thick... the instructions say to use 2-3 thin layers but my first coat went on a bit thicker due to the texture and porosity of the foam. It really soaks into the foam on the first layer and leaves a slightly textured surface due to microscopic bubbles formed while brushing. You will want to sand lightly after the first coat, but subsequent coats go on smooth. A watered-down first coat might be easier to apply.

The net result was that the wingtips look great now. The finish is a bit rubbery and pliable - not hard and brittle. You can still dig a fingernail into the foam if you press hard enough, but the "glazed" surface is much more resilient to hanger rash and could probably stand up to the punishment of repeated belly landings -- if you are so inclined. I think that with a layer of packing tissue you would dramatically increase the sheer and tensile strength of FFF without much added weight.

Speaking of which: I didn't weigh anything to see how much it adds, but my guess it that it's comparable to an epoxy and FG covering... not much.

So now that I know it works, I have a few other planes in the hangar that might get Mod-Podged...
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Last edited by warhead_71; Feb 11, 2009 at 02:08 PM.
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Old Feb 11, 2009, 02:39 PM
Tom Bass Park RC Nonconformist
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Interesting.. I'll have to stop by Michaels and try the stuff myself. Thanks for the heads up... Warhead!!
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Old Feb 11, 2009, 04:57 PM
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I seem to recall my sisters using this stuff for various craft projects, particularly laminating scraps of paper and cloth to picture frames. I never thought of using it on a plane, but I bet it would work well. My only concern would be the weight, but that could just be ounce-phobia on my part.
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Old Feb 11, 2009, 05:01 PM
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Another thought. Since it is water based I am thinking it could possibly be thinned with water or alcohol and airbrushed on. How thick is it? Does the consistency seem like it would work for that?
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Old Feb 11, 2009, 06:40 PM
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The consistency is slightly thicker than plain white Elmer's glue. It's water-based, so thinning it with water ought to work fine. Or perhaps simply misting the foam before application might make it spread on easier.

I've since read a few craft blogs on this stuff and here's how I think it might work best:

Put one thin coat on the foam, let dry, sand smooth with 150grit. Then take overlapping swatches of tissue paper and wallpaper them onto the foam... squeegee out excess glue & air bubbles... let dry, sand any seams with 200grit. Then add a final thin outer coat to seal everything. The paper combined with the glue ought to give you a much tougher skin than the glue alone. Newspaper would work well too... I recommend the funnies.

I just stopped by Michael's again on the way home from work and sure enough there was a single bottle of the "Hard Coat" - hidden behind a bottle of the "glitter". I'll give it a test this evening and see how it goes. To some degree, for fuselages I might prefer the rubbery skin of regular MP, because it will absorb a bit of abuse rather than crack under pressure. But the Hard Coat might be better for wings and fins, because it should be stiffer. We shall see.
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Old Feb 11, 2009, 08:16 PM
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Your tissue paper idea sounds really good. I'm looking forward to hearing your opinion on the hard coat. I think I'll give it a try if the plane I'm working on now isn't already too heavy by the time I finish cutting and gluing foam.
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Old Feb 11, 2009, 08:30 PM
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We used to use this stuff when I was a kid. We decorated jars with tissue paper using it. You could make some cool artistic planes by using different colored pieces of tissue paper and mod-podge them on. Increased strength and visual appeal.
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Old Feb 11, 2009, 10:02 PM
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I think Mod Podge is or was the same as acrylic medium. There was an artist that used Mod Podge as a Liquitex medium as it was less expensive.

Ray
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Old Feb 12, 2009, 02:35 AM
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GLOW in the DARK???


Very intertesting..... spring is not far away...
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Old Feb 12, 2009, 06:55 AM
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I have been using this for about two years now and love it! It sticks down fiber glass very effectively and is very user friendly. Multiple thin coats are better and this stuff needs plenty of drying time or it may be tacky in very warm weather (a little baby powder and that problem goes away- and your plane smells like a baby!)
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Old Feb 12, 2009, 07:37 PM
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In adding duribility to a plane, how does it compare to WBPU?
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Old Feb 12, 2009, 08:07 PM
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Balsaloc Substitute

Years 'n years ago we used Mod Podge as a substitute for Balsaloc/rite. I think we decided that it was the same as acrylic medium - both of which were much cheaper than the dedicated hobby products.

I remember using it as the "glue" for polyester dress liner material. Let dry then use heat to reactivate. Wait til it is thoroughly cured before shrinking. I never thinned it or used it as a filler though.

Now (since I don't build "heavy" any more) I'm thinking that it would be good for sealing foam if applied with light coat(s) applied with a trim foam roller.
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Old Feb 13, 2009, 10:12 AM
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Quote:
Originally Posted by Bugman Jeff
In adding duribility to a plane, how does it compare to WBPU?
The regular MP is more pliable (rubbery) than WBPU - which can be good or bad depending on your application. I think a rubbery coat would be great on a fuselage or any foam that just needs a general coating to protect the foam from hangar rash - or to seal the foam before spray-painting. Because it is pliable, it won't add much "stiffness" to your foam - at least not by itself. I think if you combined it with a paper skin it would be terrific. After all, this stuff is made specifically to soak into paper for decoupage projects. Regular gift tissue paper ought to do the trick -- or newspaper, which is slightly heavier but has more "tooth" to it.

The "Hard Coat" MP is much harder, as the name implies. I applied some to an old Clark-Y FFF wing from a crashed plane, just to test it: The results were pretty good - almost indistinguishable from WBPU, though I had problems with leaving brushstrokes in the first coat again. But even with WBPU I had to sand between coats. I think the porous nature of foam creates air bubbles while brushing ... which in turn creates streaks. Again, I think if you use paper or some other substrate to skin your plane, you'll get a lot better results, and probably the streaking will go away.

I've read reports that MP can remain "tacky" after curing, but I painted directly on it with the 99-cent spray-paint from Kmart and had no problems.
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Old Feb 13, 2009, 10:17 AM
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Originally Posted by Tripod333
GLOW in the DARK???


Very interesting..... spring is not far away...
Yes, and "sparkles"... that would be dazzling on a night-flyer with LEDs!
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Old Feb 13, 2009, 12:03 PM
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http://www.rcgroups.com/forums/showt...3#post11062573

Post #12 here shows a little guy covered in tissue paper ran thru a printer. Doped on with WBPU. Tissue does make it really strong. I played around with hinging with it also. It also makes really good hinges as the tissue stay's flexible. I'd like to hear how the Mod stuff works out.
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