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Sun effects on Ultracote

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Old 06-25-2017, 06:28 PM
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zwibelturm
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Cool Sun effects on Ultracote

It was 90 degrees today and 10 minutes in the sun loosened and wrinkled the Ultracote covered, balsa sheeted foam on my 30% Extra (again). I've tried BalsaRite, no- BalsaRite, ironing, heat gun and hand pressure, re-shrinking, pin-holing, and air squeegee out through channels at the edge. Colors are blue and white and the blue is worse. Looks great in the hanger but a trip to the field and I'm back home ironing again. Any suggestions are appreciated.
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Old 06-30-2017, 12:51 PM
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I'm losing confidence that Ultracote is the better choice of plastic film coverings. For the reason you detail, and the aging process which has the clear plastic separate from the colored adhesive.

In fact, my last build got something else and I'm happier with it.
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Old 07-02-2017, 07:59 AM
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speedracerntrixie
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While I am mainly a Monokote guy, these tips will work well with Ultracote as well. IMO it all comes down to the wood prep and applying the covering so it requires very little shrinkage. I will typically finish sand the wood down to 400 grit. Remember that if you use a heavier grit paper, it will leave behind scratches in the wood that will hold air between the wood and covering. The air of course will expand when heated. Next is the biggest thing. Get the wood CLEAN! I bought a pack of black cotton T shirts just for this. After blowing off the part with compressed air, dust the parts with the black T shirts until no more wood dust comes off. The black color will really show you just how much dust is on the wood. Usually it takes 6-8 times over to really get your parts clean. Once the parts are clean, apply the covering in a manner that will require very little shrinkage. An example of this is covering a balsa sheeted for an wing. I first tack down the root of the wing and then alternating between leading edge and trailing edge I pull the covering tight as I go until I get to the tip. I leave the tip open and only have the root, TE and LE tacked down and sealed at the edges. I next get out the heat gun and a cotton T shirt. Use the heat gun starting on the root and shrink the covering and immediately wipe the covering with the cotton shirt with moderate pressure. This needs to be done before the adhesive has a chance to cool. Work your way to the tip and then seal the tip with your iron. Even tough the covering was applied tight, you will be amazed at how much air you remove during this step. The air was also removed when hot so any that remains has cooled and contracted and will be far less of an issue when warmed back up by the sun. Now you are ready to apply your graphics. With Ultracote, use very low heat and work from one end to the other being careful not to trap air. It takes a lot of time but can be done. This is one of the reasons I prefer Monokote, trim can be applied like a window film. Simply spray the adhesive side with Windex that contains ammonia, place it on the surface and position. With a peice of 1/4" balsa, squeegee the Windex out and allow to sit over nite. Come back the next day and iron the graphic with low heat once and then high heat once. Not sure any of thIs will help with your current issues but perhaps on future builds. Unfortunately once you are at this point, not much can be done to correct the root problem of having poor adhesion and trapped air.
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