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Old 08-05-2019, 12:00 PM
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tbzep tbzep is offline
Dazed and Confused
 
Join Date: Mar 2005
Location: TN
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I've done it with finishing epoxy (something like a 1 hour working time) on HPR plywood fins, some with fiberglass reinforcement and some just with epoxy. It isn't bad with powered sanders or sanding blocks on large plywood surfaces, but it would be a royal pain to do it on small balsa fins. You can get a glassy looking finish with slow setting finishing epoxy, but it usually has imperfections such a dimple here and there, bits of dust that look like mountains compared to the smooth areas, etc. so it still needs some sanding.

There are little intricacies and tricks to just about any balsa filling method.

With papering, I've had the paper bubble up when the model was out in the sun at a launch and I've had paint separation a couple times, so you still have to pay attention to detail, prep surfaces, etc.

With Fill-n-finish, you pretty much need to do it with the fin already mounted to keep it from warping. I've done both sides at the same time and still had uneven warpage. I can usually take care of it by selectively wetting small areas.

With Brodak and other dope based filler/sealers, there aren't really any gotchas. You just have to be willing to do some sanding. A bonus is the stuff smells great and opens your sinuses. You sometimes see pretty colors and exotic creatures too.
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