Q-40 Racing Discuss AMA 422 and any other variants of Quarter 40 racing

Polyester resin mold / Epoxy resin Fuse ???

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Old 11-23-2010, 04:28 PM
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oddy
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Default Polyester resin mold / Epoxy resin Fuse ???

Hello everyone.

I made hydrocal molds for a Q40 fuselaje.

I use Polyester resin for sealing the mold (3 layers) sand it for a smoother finixh, wax my mould with 6 coats , spray a separating agent and made my fuse of Fiberglass with epoxy resin.

Unforunately when taking the plug out it was stuck

Could it be used polyester resin sealed molds for making epoxy resin fuselages???

Or does it have to be epoxy moulds for epoxy fuse and Poliester resin for polyester pieces.

Any info will be very much appreciated

V*ctor Arreola.
arreolavictor@hotmail.com
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Old 11-23-2010, 07:49 PM
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Default RE: Polyester resin mold / Epoxy resin Fuse ???

Oddy,
SO what you are saying is that when you took the plug out of the mold you just made, the plug stuck to the mold? Or was this a part that you just laid up in the mold?

If the plug stuck in the mold (when you made the mold) I would think that the heat build up from the resin might have caused the paint on the plug to get too hot and come off the plug. I haven't used polyester resin to make a mold, but I think it can get hotter than epoxy and this could have caused the wax barrier and/or paint failure and stuck the plug in the mold. I use Part-all #2 wax and Part-all #10 PVA release with a very slow laminating resin (lower heat build-up). I also had a plug issue in a mold a couple of years ago from using cheap rattle can paint and no PVA on the plug before molding; Never again!! I would think the polyester resin would be fine, as long as you start with a good catalyzed paint on the plug, good high temp molding wax and a molding barrier(PVA) on top.

If you have the molds and the first part was what stuck in the mold, I would look at the wax/PVA you used as the culprit of the sticking issues.

Maybe a little more info may shed some light on it.

By the way, how's that donkey getting along these days?
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Old 11-26-2010, 11:28 AM
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Default RE: Polyester resin mold / Epoxy resin Fuse ???

Scorpion, thank you very much.

Actually its not a Donkey it would be a Female Donkey called MULA and is not precisely applicable for my molding knowledge and skills an as you can guess , but still willing to "Have the pelos in my hand" eventually on molding techniques so I will keep trying and experimenting.

I have done some other hydrocal molds for Q500 fuselages using a High Gloss epoxy resing with very good results and without having pieces stucked.

What was stucked was the first FG Piece coming out of the mold after having finished and sealing them with this Polyester Resing......I think maybe polyester resin was not entirely stiff yet, I´ll try again leaving more time for polyester resin tu entirely cure and as you mention with better wax and PVA

Thats the beauty of hydocal molds,,,,,,,,practically if something goes wrong you can just do it again and with very little cost added but of course I would rather have it correctly done next time.....Im not willing to be pouring hydrocal all the winter.

One thing I did different this time is that the original pink foam fuselage from where i made the molds, I seal it with epoxy resin so it was very stiff and gets out perfectly from the hydrocal molds without a scratch and they are ready in case another set of molds are needed, which is the case.

Thanks for your help,
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