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Apr 07, 2007, 02:12 AM
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Gel coat and epoxy mold???

Last edited by Minhuahua; Feb 19, 2008 at 12:07 PM.
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Apr 07, 2007, 03:03 AM
You must die! I alone am best.
slopetrashuk's Avatar
I doubt it. Epoxy is not known to stick to polyester well at all.
Apr 07, 2007, 07:59 AM
No fuse too fat
slopeiron's Avatar
What Andy said. Don't mix epoxy and poly.
Apr 07, 2007, 08:11 AM
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Akerman's Avatar
We've been using Polyester gel coat as paint (in the mold) for epoxy wings and fuses, works great and sticks well. For molds, we use epxoy gelcoat or tooling resin.

Anyway, before you try any new stuff, DO try it on a scrap piece before.
Apr 07, 2007, 08:24 AM
I don't want to "Switch Now"
pmackenzie's Avatar
Good instructions here that explain how to use epoxy for moulds.
They use Colloidal Silica as an additive to regular epoxy to create a gel coat.

Pat MacKenzie
Apr 07, 2007, 10:21 AM
No fuse too fat
slopeiron's Avatar
One thing I would add to what Pat's link says, is that when you mix in the Cabosil you can't really just add "a little" like it says to. If you try to do that you will end up with a lumpy mixture of resin and little chunks of dry Cabosil that will never mix in no matter how long you stir it.

Here is how I make my tooling coat -
* Mix the resin well first, then pour off about half of it into another cup.
* Add Cabosil to one cup until it starts getting stiff enough to tear all the little lumps of Cabosil apart and turns into a smooth creamy mixture.
* Start stirring in resin from the other cup to thin it back down until it is about like honey.
* Add some graphite powder to make it black.

You don't want it too thick or it will trap air bubbles. They should be able to slowly migrate to the surface. On the other hand, you don't want it so thin that it just runs off the part either.
Apr 07, 2007, 11:51 AM
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Last edited by Minhuahua; Feb 19, 2008 at 12:07 PM.

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