When making a mold. if I use a 80g Emulsion Bound CSM as a sealer layer after Gel Coat which needs a polyester resin can I then use 300g Powder Bound CSM with Epoxy Resin for all the remaining layers of the mold? I realize that I can use polyester resin on the powder bound CSM but I would rather use Epoxy even though it is more expensive.

One of the reasons I would like to use epoxy resin is the plug I am building is made out of foam board from the local home depot and I have read that you can seal it with an epoxy resin and not a polyester resin. Does anyone know if this is true? I do know you can't do it with the polyester resin for a fact. I tried it and it ate the foam just like they said it would.

I guess that brings up another question.....Can you put CSM with polyester resin ontop of epoxy resin?

Thanks,

   Dennis G 

Hi Dennis

I use polyester resin over styrofoam all the time. It will melt so you have to seal it. Because it is so cheap and easy to rough shape with a cheese grater file I use it all the time.

Here is the trick. Rough shape and board sand. Now spray a mist coat of 3m contact adhesive. (the 3m stuff will not attack the foam)

Now cover the whole thing with aluminium foil that you need to steal from your wifes kitchen.

Make sure you overlap. I use a small roller to get the aluminium to lay down. I then use packaging tape on the seams.

Yah it doesn't look good and its folded  but it is less than 1/32 thick distortion.

I then put on a few coats of wax. Bing! your done.

Now put one coat of glass matte with the polyester.

When this cures build up all the layers you need, it will not attack the foam.

Often at this point I will do a rough trim and dig all the foam out and mount this mock up to a wood frame.

I then go at it with lots of bondo and sculpt it with a cheese grater file while it is still in the rubber state.

Fred