Water-based polyurethane??

I'm painting a model with latex paint -- first try. The latex isn't fuel "proof" for glow fuel, so I need to cover it with a clear coat. I was
thinking of using Polycrylic (thinking that was a water-based polyurethane since its cans are right next to the oil-based polys at the store), but I've found out that Poly c isn't even really fuel resistant. So, I was wondering if anybody knew of any brand names for any easily available water based polyurethane that can handle 10% nitro. I've tried looking at Home Depot, a paint store, and a local hardware store for Verathane, but wasn't able to find it.
Thanks, Vicki
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On Tue, 15 May 2007 19:44:05 -0400, Victoria Heisner

Vicki-
I've used MinWax Polycrylic Clear Gloss (water based) as both an adhesive and finish with silkspan over poly foam, and also use it for field boxes and test stands. Works for me.
Abel
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wrote:

I have used Minwax Polycrylic with good results up to 10% nitro.
Spray one coat and let it cure out for a week then put on a second coat. A week later use some soft spread auto wax on it carefully and go fly.
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Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

MinWax Polycrylic (waterbase polyurethane ) is fuel RESISTANT WITH THE FOLLOWING CAVEATS:
1. Do not expose the poly to fuel residue for a MINIMUM of 7 days.
2. Do not let the residue remain on the plane longer than 4 hours. (I suggest cleaning the plane off after about 2 - 3 hours.) After 4 hours the residue will begin to soften the poly.
Waterbase poly WILL NOT yellow with age, so it is safe with whites and other light colors.
If you want a fuel PROOF clear coat, use Ultracote Clear and let dry for a minimum of 72 hours. Lustercrap will also work if you want to fight with the spitting it usually has.
You can also try an ACRYLIC clear ENAMEL (Krylon, Dupli-Color, etc. ) HOWEVER, I strongly suggest doing a test panel 1st. Let the clear dry for 24 - 48 hours, then put it in the exhaust stream of a running engine for about 5 - 6 minutes. Let the residue remain on the test panel overnight, then clean it off. You will know immediately if it is fuel proof or not. I have had excellent results with Dupli-Color "Truck & Van" paint in colors.
If you decide to try the Dupli-Color, read the label carefully. They have acrylic enamel AND acrylic lacquer. You can put enamel over lacquer, but not the other way (the underlying paint will "craze".)
Check RC Universe http://www.rcuniverse.com/index.cfm in the Discussions area/Tips & Techniques. Do a search on Campy. I have done some experimenting with various clear coats and my results are posted there, HOWEVER, I DO RECOMMEND DOING A TEST PANEL FIRST before commiting to the plane.
Hope this helps.
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Contrary to popular belief, Minwax Polycrylic is NOT polyurethane! Read the can - the only places the label mentions polyurethane is where it says for floors and other tough applications you should use Minwax fast-drying polyurethane (oil-based) INSTEAD OF Polycrylic.
I've used both Minwax Polycrylic and Flecto's Varathane (both are water-based) on cabinets and shelving for over ten years. I like the color Polycrylic gives to red oak, but glow fuel dissolves it immediately even after years of curing, while Varathane, even on my engine test stand, holds up fine.
If you can't find Varathane, read the labels on cans of other water-based coatings and check that it really is "polyurethane", and not simply saying that it's not as good as polyurethane.
-Dave
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