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Question on Fiberglassing

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Old 10-23-2006, 03:43 PM
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chuck l
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Default Question on Fiberglassing

I'm experimenting on a couple of deceased airplane parts, trying to compare Zpoxy and Polycrylic. I ran into a problem with the Zpoxy fiber glassing around the leading edge of a wing. After the second coat, there was a build up of epoxy on the underside of the wing where the epoxy flowed, even though I was trying to be careful. The Zpoxy was diluted with denatured alcohol at a 30% ratio. This much alcohol seems like too much because it was just like water. I don't want to start a big debate, but it seems like the Zpoxy is a faster method that Polycrylic where you apply 5-6 coats after putting on a couple coats of sealer. I'd probably go with the Zpoxy if I can learn how to keep the Zpoxy from flowing around to the underside. Any comments, recommendations?

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Old 10-23-2006, 07:20 PM
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Default RE: Question on Fiberglassing

Chuck1,
ZPoxy is awesome. However, water like is too thin. You want it like milk, (a little thicker). You have to plan for over runs and spills. use a playing card for a squeegee. Once dry, light ssand with 400 grit emery cloth. Apply second coat if you wish and again use 400 grit emery cloth, then 600 grit emery cloth. I prefer to use .75 oz. cloth. Some folks prefer West Systems, but I don't care for the added expense and processes. Look at the planes in my gallery or my C-47 in my post here on RCU, "C-47, Normandy Tribute June 6, 1944". All are done using my above description. Good Luck.
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Old 10-23-2006, 07:42 PM
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chuck l
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Default RE: Question on Fiberglassing

Flak,

Nice C47, I look forward to hearing how she flies. Anyway, about what percentage denatured alcohol do you use with the Zpoxy?

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Old 10-23-2006, 10:44 PM
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Default RE: Question on Fiberglassing

Chuck1,
OK, suppose I am going to glass a 60 size P-51 Wing. I take the 2 Z-Poxy tubes and squeeze in the amount I believe will cover one side of the wing nicely. I add enough Denatured Alcohol to make the whole mess look like milk. I stir the brew and pull out the stirring stick slightly. Looks about like milk, I'm happy. I use a cheap throw away paint brush and brush the mixture on the cloth as it's lying on the wing. Once applied, I can use a playing card for the squeegee work. Any bubbles can be slit with a Xacto knife. I usually let it set for 24 hours afterwards for a good cure. I don't use measurements as I have been doing this kind of stuff so long it's a natural process. There are several good videos on fiberglassing that you can get at your local hobby shop. Good luck. Thanks for the koodos on the C-47. I'm just waiting for the weather to cooperate with my days off.
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Old 10-24-2006, 06:31 AM
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Default RE: Question on Fiberglassing

What Flak says, plus a couple of things he probably forgot...........

If you're just beginning, you're probably going to wind up with some areas that have way too much resin on them. Trying to move all that excess with a squeegee is not a good idea. Have a roll of toilet paper handy and use the roll to sop up some of the excess. Just press the side of the roll down on the puddle and let it soak some of the resin off the surface. Unroll and discard that wet paper, and squeegee out the rest.

Also.... every batch of epoxy will kick at some time after application. It will become a soft solid. It'll still be very pliable, but it's quit running. Just after that happens, it's very easy to trim with a razor. It won't be anywhere as easy when it cures hard. I usually try to catch that time and do all my cleanup trimming then. Any runs and wrinkles around the edges are lots easier to deal with right then. Use a brandnew single edge razor and expect to throw it away. And old used Xacto won't cut it..... The razor will, and easily.

The thing you're shooting for is to have the wet layup have no shiny areas. Shine happens when there is too much resin for the cloth. It's resin above the surface of the cloth. It's dead worthless weight. If the cloth looks transparent and dull, it's got enough resin for full strength and not any that's just dead weight. You'll understand the different looks almost right away.

Try to get the entire piece of cloth generally down before you start dinking with small problem areas. Once it's all placed with resin, then go back and sort out the little wrinkles and puddles.
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