Polyester resin sealed with MAX ACR marine safe epoxy resin

[CyberPunk]

Hello all!

Well we are building a 10'x14'x4' plywood ray tank and laying 5 coats of resin and fiberglass mat. What I am planning on doing is doing the first 3 coats in polyester resin which I know can and will prob leach junk into the water, so to seal that in I was going to lay 2 to 3 coats of ACR marine safe epoxy resin over that to seal it up (I have tested that the ACR will cure and adhere to the polyester resin just fine). So my question is do you think this is safe and will seal off that polyester enough where there shouldn’t be any worries of leaching stuff into the water? I would just use the MAX ACR stuff but there are three reasons I am not, one being its $80 a gallon v $30 (We are going to be using 13 to 15 gallons), 2 being polyester will stick better to the wood and three I don't have to order it and wait a week to get it instead of getting it locally.

Thanks in advance for your help!

P.S. I attached some pics of the build, we will be doing a complete build thread when its complete

 

[Buckdog]

Nice setup!
First off what I highly recommend is that you call Polymer Composites and talk to the lead chemist. I worked with him on my tank: http://www.monsterfishkeepers.com/forums/showthread.php?t=143924
He is great at explaining how composites work.

In short what we did was NOT cover the inside with glass but did the outside instead. Several folks here have contacted both Polymer Composites and other resin manufacturers and they say the same thing...to cover the outside of the tank with glass. Its a form of strength encapsulation. The inside of my tank was done by thinning down the epoxy and letting it leach, or "bite" into the wood. Successive coats were applied on top of that. Wood glue was not used but a thixotropic or thickened version of the MAX instead. Then the outside was glassed. The tank is very strong and just flexible enough.

You are on the right track. Good luck and have fun.