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Polyester Resin mold for epoxy resin fuse?

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Old 11-23-2010, 03:59 PM
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oddy
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Default Polyester Resin mold for epoxy resin fuse?

Hello everyone.

I made hydrocal molds for a Q40 fuselaje.

I use Polyester resin on the hydrocal moulds (3 layers), wax my moulds and made my fuse of Fiberglass with epoxy resin.

Unforunately when taking the piece out it was very difficult and molds were damaged.

Could it be used polyester resin molds for making epoxy resin pieces???

Any info will be very much appreciated

V*ctor Arreola.
arreolavictor@hotmail.com
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Old 11-23-2010, 04:53 PM
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Default RE: Polyester Resin mold for epoxy resin fuse?



Yes, I do it all the time. Either the molds were not fully cured and still gassing some or your release wax/film wasn not suffiecent.

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Old 11-23-2010, 08:07 PM
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Default RE: Polyester Resin mold for epoxy resin fuse?

Use partall release wax, 4 coats or more on a new mold. Then spray PVA #10 on that. Let dry overnight. Nothing will stick to that.
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Old 11-23-2010, 09:45 PM
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Default RE: Polyester Resin mold for epoxy resin fuse?

I have been making polyester molds since 74'. I have pulled parts using poly and epoxy without problems. I have to ask, did you gel coat the plug before layup? Did you sand it out with 800 - 3200 grit? Did you seal the mold? How many coats of wax (mold magic or the equivalent) did you apply and buff out? & did you hand or machine buff it? The last Q is: did you use PVA in the mold and how long did you wait before layup?

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Old 11-24-2010, 08:32 AM
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Default RE: Polyester Resin mold for epoxy resin fuse?

My system on new plugs or molds is: Three or four coats of Partall then I wipe on a coat of PVA using a small (4" square then folded) cotton t-shirt rag. Let it dry and then repeat the process being careful when you wax to not pull up the first PVA. Yep, belt and suspenders works fine for me.
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Old 11-26-2010, 07:57 PM
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Default RE: Polyester Resin mold for epoxy resin fuse?

Everyone thank you very much, Il´ll be trying once again with polyester resin.


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.

I think maybe as commented by speedracerntrixie 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 advantage 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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