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Newbie Question on Fiberglassing

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Newbie Question on Fiberglassing

Old 07-31-2019, 07:48 AM
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millheim
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Default Newbie Question on Fiberglassing

I've been building plane kits for a while , but have always used heated stretch-coverings (monocote, etc)
I'm starting a scratch build on a 1/5 scale I-16 Rata, and would like to try my hand at fiberglassing, molding etc. I've read a lot about glassing techniques,
but have a very simple question. If one normally sheets the plane with balsa, why not just fill, prime & paint the balsa? I've read that the glass adds minimal
strength, so what is the main advantage of adding the glass over the balsa? If I've missed this explanation somewhere else, please point me to that thread.
Sorry for what is probably a very trivial question. Thanks.
Old 07-31-2019, 08:50 AM
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R8893
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Kevin, the glass will help prevent cracks and the wood splitting over time. Same as tissue and dope in the old days. Primary purpose is to create a uniform, impervious surface for the paint. Glass and resin take a whole lot fewer coats than tissue and dope.
Chuck
Old 07-31-2019, 08:56 AM
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millheim
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Thanks Chuck. I assumed it was something due to longevity, fuel-proofing and quality of finish. I'll keep reading on glassing techniques and try my hand at a new "skill"
Thanks again.
--Kevin
Old 07-31-2019, 09:10 AM
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speedracerntrixie
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If you were to just brush straight resin on the wood the wood will absorb a great dealof the resin. As a result the wood will swell some. That means more sanding and most likely another coat of resin which would be more weight. It will also take more primer and of course that is more weight as well. A thin layer of 3/4oz cloth will actually keep the resin from perpetrating very far into the wood. Imagine a wet sponge retaining the water as it sits on a counter top. Once the epoxy resin has cured for a couple days you can lightly sand with 320 grit, dust off and smear some light weight filler over the entire surface. Let that dry for a couple days and then sand smooth with 320 grit again. The reason for that step is to fill the weave of the cloth with something lighter then primer. Use a good quality auto epoxy primer or Klass Kote primer. Should only take two applications, sand as much off as possible leaving only what is needed to fill low spots. Then you are ready for paint. I always put down a coat of white base first. Makes for a uniform canvas for your colors.
Old 07-31-2019, 10:40 AM
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millheim
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Thanks Speed,
That makes a lot of sense. I'm looking forward to trying this process.
Old 07-31-2019, 11:32 AM
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speedracerntrixie
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Glad to help, if you have anymore questions just give me a shout.
Old 07-31-2019, 03:32 PM
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another reason you can not just sand, bondo and paint is that the wood will absorb much more of the paint than the bondo areas and there will be major inconsistencies on the entire surface. Glassing makes for one consistent surface ready for primer and paint. Good luck. It's not hard to do and will produce a far superior result that you will be proud of.
Old 07-31-2019, 06:11 PM
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speedracerntrixie
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How about a little inspiration? This airplane was painted using the method I described. It did however take 6 weeks. Just can't cut corners on a quality paint job.
Old 08-01-2019, 04:15 AM
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millheim
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Thanks Vettster. Being a long-time woodworker, I understand your point when I think about how a single piece of wood can take stain very irregularly and become blotchy.
Old 08-01-2019, 04:17 AM
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millheim
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Thanks Speed. That turned out beautiful! As I mentioned in a previous reply, I'm also a woodworker and understand that prep for finishing and the actual finishing process can not be hurried if you want a great result.
--Kevin

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