FrankRC1

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[]What type of alcohol do you thin resin with?

solarvolt

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I've always used denatured alcohol.

cknaack

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I have always used (12+ years) Isopropyl Alcohol at a 90%+ concentration. I have no problem finding the 99% version at Walgreens.

CafeenMan

I don't. I think thinning resin is a really bad idea. It's a constant argument here at RCU, but the bottom line is that it's not necessary and can cause problems. Why do it?

If you want thin resin, either use finishing resin which is already low viscosity and made for applying fiberglass cloth

or

Put the mixed resing in a pan of warm water for a couple minutes. Warming it also speeds the curing time, so if you have a large area to cover then use very slow-drying epoxy or laminating resin.

Problems with thinning resin:

* Causes it to shrink
* Interferes with chemical cure
* Causes resin to stay rubbery or become brittle

Now everyone can tell me that I'm wrong.

cknaack

My Feedback: (1)

That's the great thing about the United States, freedom of speech and opinion.

Although you have valid points, opinions do vary............ I have not experienced any issues when using it to thin epoxy for fuel proofing. With that said, I would NOT thin epoxy for a structural application. I prefer using the Anchor Bond products as they flow much better than the "house" brands or even the Z poxy.

solarvolt

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I've used denatured alcohol for structural purposes and have never had any problems.
And really, it all comes down to what works for "you".

FrankRC1

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Thanks Guys for the help!!! Frank

mpriestley

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Well, a bit off the subject but the most current relevent thread to ask the question,


I am trying a new technique out for fiberglassing, I am building a Combat Models F-16, and the way they do it is to put down the cloth with Zpoxy thined by denatured alcohol at a 60/40 ratio. You use a cheap paint brush and it worked great for the application of the fiberglass (did not have to do any "screening" at all... )

here is where the different part comes: instead of reaplying a very thin layer of epoxy or resin to fill the weave you use Light weight spackle

I bought (by accident) Vinyl spackle which is a lot heavier in the can than the lightweight spackle ( alot heavier)

I am concerned that I have made a mistake that will affect the performance of this plane. But all it is doing is filling the weave and then I will be priming and painting.

Help put my mind at ease.... PLEASE...


OH Yea, you apply it while sanding with 320 and it really comes out cool and smooth and a lot less work than other ways I have done fiberglass.

I have completed all but 20 percent of the fuse with the Vinyl spackle.... should I be truly concerned?

CafeenMan

You're right about filling the weave. Anything on top of the weave is needless weight. Sand down until you're as close to the cloth as you can get without cutting into it. If you need to do more filling, switch to sandable primer.

Personally, I wouldn't use spackle as a filler, but your plane will be fine.

mpriestley

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so you dont think it will add any noticable weight?

I actually think I like it better as a final surface than the lightweight spackle...

I am a bit worried because I had read a thread about the plane where a guy used a second coat of resin and He said he put a lot of paint on and long story short it would not fly...

Thank you for easing my fears...

CafeenMan

Everybody knows how to do a bad paint job and then they claim paint is heavy. If you do it right, it can be as light as any other finish and I'm not exaggerating that. The secret is to keep every coat thin by sanding. It's a lot of work, but it's worth it for some planes.

A second coat of resin is almost always a bad idea. It's better to fill the weave of fiberglass cloth with a light filler - not resin. Resin is good for adhering the cloth and that's all it should be used for.

So yes, your plane will be fine and it will not be over-weight if you use lots of sandpaper and elbow grease.

mpriestley

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Thank you buddy!

Back to sanding.....