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  #1  
Old 08-05-2019, 10:31 AM
metlfreak metlfreak is offline
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Default Epoxy Resin to seal Balsa.

Yeah? No? Why Not?
Anyone ever try brushing on or applying epoxy resin to fins? It would make them harder that glass and probably just as smooth I should think. These days with lighter resins like Famowood Glaze Coat it seems like its doable and would be better than papering fins.
Anyone try it?
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  #2  
Old 08-05-2019, 10:39 AM
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ghrocketman ghrocketman is offline
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Papering fins just plain sucks.

I use NOS good-old-fashioned Aero Gloss Dope Balsa Fillercoat and Sanding Sealer.
You can get Sanding Sealer still from Brodak (just as good) or Sig (needs 1 part thinner to two parts sealer).

Epoxy is not generally used due to it being HEAVY.
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Old 08-05-2019, 10:52 AM
jetlag jetlag is offline
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Quote:
Originally Posted by ghrocketman
Papering fins just plain sucks.

I use NOS good-old-fashioned Aero Gloss Dope Balsa Fillercoat and Sanding Sealer.
You can get Sanding Sealer still from Brodak (just as good) or Sig (needs 1 part thinner to two parts sealer).

Epoxy is not generally used due to it being HEAVY.



Heavy and is difficult to sand down on a fin without screwing up the wood. Also, finishing resin adds no strength to the fin.
I use the Brodak and love it!

Allen
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Old 08-05-2019, 11:22 AM
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LeeR LeeR is offline
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Brodak sanding sealer is great. Iíve also experimented lately with Elmerís Wood Filler. It will warp fins if you donít do both sides at the same time. Some have posted that once you fill the opposite side, the warping goes away. That was not my experience with thin balsa. I prefer it on thicker balsa to minimize or eliminate warping. Works really well on nose cones. If the balsa has any dings, the wood filler will work well to fill them. If you are using a sanding sealer, you could still fill dings prior to use. I prefer to us an RC Covering Iron to raise dents in balsa. Wet the dent and run the iron over the area to lift the dent. A regular clothing iron would probably work if set to a low setting.
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Last edited by LeeR : 08-05-2019 at 11:03 PM.
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  #5  
Old 08-05-2019, 11:37 AM
metlfreak metlfreak is offline
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Quote:
Originally Posted by ghrocketman
Papering fins just plain sucks.

I use NOS good-old-fashioned Aero Gloss Dope Balsa Fillercoat and Sanding Sealer.
You can get Sanding Sealer still from Brodak (just as good) or Sig (needs 1 part thinner to two parts sealer).

Epoxy is not generally used due to it being HEAVY.

Oh yeah I didn't think about how heave epoxy was.

Quote:
Originally Posted by jetlag
Heavy and is difficult to sand down on a fin without screwing up the wood. Also, finishing resin adds no strength to the fin.
I use the Brodak and love it!

Allen

I was thinking of adding it as a last step before painting so wouldn't be sanding it which means it will also require a Lacquer paint more than likely...It's probably more trouble than its worth and expensive. I've always been the type to do things that other people don't though usually just to be different or adventurous.
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Old 08-05-2019, 12:00 PM
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tbzep tbzep is offline
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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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Old 08-05-2019, 12:10 PM
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I used to love the smell of Vickís Vapo-rub when I was a kid. As an adult, Iím more partial to Brodak ...

Note: Do NOT rub on your chest.
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  #8  
Old 08-05-2019, 12:16 PM
astronwolf astronwolf is offline
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Quote:
Originally Posted by metlfreak
Oh yeah I didn't think about how heave epoxy was.

It's not THAT heavy. I coat balsa fins with tissue paper and epoxy for competition models that have to be very light. But I don't gob the epoxy on. I use just enough to wet out the tissue paper, and I sandwich the fins between two sheets of glass and put a weight on it. They come out very smooth.
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Old 08-05-2019, 12:18 PM
astronwolf astronwolf is offline
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Quote:
Originally Posted by tbzep
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.

The cure is to seal the fins first. Either with brush on dope, or a spray lacquer dope like Deft.
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  #10  
Old 08-05-2019, 01:24 PM
metlfreak metlfreak is offline
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Quote:
Originally Posted by tbzep
I've done it with finishing epoxy (something like a 1 hour working time)

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.

Nothing beats the end results you get with Brodak.
I too always have issues with warping fins when using sanding sealer etc.
You can do one side let it completely dry (will be warped) then do the other side, if your lucky it will go back straight or nearly straight. I hate it though.
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