Fiberglass background (resin)

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Aquarium Advice Newbie
Nov 9, 2010
Ok i have view a couple treads on here about people wanting to coat there diy rock background with resin. The question was asked " what is a safe resin to use" but no one gave a good answer. I recently made myself a fiberglass background after seeing someone on youtube doing it. Mines came out great got it painted with the "look like stone" spray. Now im stuck, because the last step is a problem. For the next step i am supposed to seal the background with a coat of resin. Came to find that a few people are saying that resin can leak chemicals, and kill your fish. Now i ask the question again.. What is a safe resin/product to use that will clearcoat/seal the background? I found this stuff in the craft store (Castin'Craft Clear Polyester Casting Resin) any thoughts on this product? I see folks making plywood aquariums, what resin are there using? I when to the local fiberglass supplier, and they was not much help.
I've seen Sweetwater Epoxy from Aquatic Ecosystems Inc. used over plain plywood. I would try any resin intended for boat repair.
I've actually been doing research on this and would be interested to hear anybodies experiences. So far what I have found is that resin, if it is mixed properly, after it fully cures, it will not leach and is essentially plastic, however I'm not 100% on that yet.
I have mixed resin and hardener and may not have mixed it 100% as it after a few weeks became soft and parts of it ended up mixed in my gravel the Kuhli Loaches lasted a week before I found a piece still in my tank so I made the inline filter pump for my Gravel vac to help remove it
If you have alternative options id suggest that, Lol I use to work for a fiberglass company and majority (everything I ever came across) was toxic to human health .. so I would imagine it wouldn't be a good idea to use a resin. maybe check out "polymer clay" or google natural substitutes?
On the cover of this Clear Polyester Casting Resin it shows that you can make glass cups with it. Also what iv learned so far once the mix is done right and let fiber glass cure in high temp it becomes non toxic. Im still not 100% sure, but im am gonna put my FG background in my tank, and see what happen.
Fiberglas is used to make containers to keep fish in so it stands to reason that once cured it is non toxic. The fact that the resin and hardner are toxic does not mean they are still toxic when cured. So, anson, I would go ahead with the polyester resin you used to make the background.
Im having the same problem with what im trying to do im using fiber glass letging it cure painting it up so it looks the part but then comes down to the clear coat what could i use to seal it

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I use several coats of clear Plasti-Dip on my styrofoam backgrounds. No problems with them, and I've had two tanks with them for well over a year. If you want something thicker/harder, you can use a marine epoxy resin - like Sikatop 107.
If i was to use two pack paint used for cars and a clear seal would it be fish safe as onces its cured its hard ??

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