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 

Thanks for the responses.....Some good info......I have been doing alot of reading and watching videos.....That may be good and bad...who knows?.....

I was wondering if any one has just painted the foam with a Laytex paint then used dry wall compound over it? I have read that you can seal the foam with the paint then you should be able to go over it with fiberglass. If I read correctly you should be able to use a polyester resin. who knows if that is correct.  I could try it with some scrap pieces to see I guess.

The reason I want to use drywall compound is I have seen a video that the person used it to shape their plug due to it being cheaper than bondo and easier to sand. I like that Idea.

All I want to do is add thickness in some way to my plug so I can finish shape it.  Preferably would like to do it as cheap as possible. I have attached a pic of the tunnel I am going to make. This pic is before I cut and shaped the foam to roughly the shape I want. I made my rough plug 1/8" (3.17mm) under size so I had room to build it up to finished shape.

Fred....Your way sounds fairly easy and cheap I may give this a try.  One question....After you put the foil and tape on why did you wax it? Was it because you wanted to dig the foam out?  If I don't wax it will the Fiberglass stick to the Foil? I would prefer this.

Thanks for the feedback,

                       Dennis

I put the wax on as a guarented barrier. I could also release the foam plug a bit better. But it still sticks real good.

If you want a pro plug you have to go with a hard surface. (in my opinion) You want to treat it like a car body job. The shape has to be perfect but the finish doesn't. Because to get a glass like shiney mold you have to wet sand and polish anyway. A gallon of bondo is less than $20 bucks and goes a long way. Then primer surfacer/ spot putty/ primer surfacer again. Board wet sand/ polish etc make mold.

Fred