# Fighting condensation - epoxy or varnish



## idris (3 Oct 2019)

(This is possibly more a woodwork question but, as it's DIY aquarium related, I'm hoping there may be useful experience within UKAPS.)

My custom tank stand / hood is heavily varnished ply. But after a 8yrs of good service, and despite cover glass, the varnish on the inside of the hood is no longer protecting the wood from condensation.

Rather than multiple coats of varnish, is epoxy likely to be much better at resisting the condensation in a tank hood?

(And any thoughts on fitting a small PC/CPU fan as an extractor?)


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## Keith GH (4 Oct 2019)

Idris

Even though I taught the Cabinet Making trade for 26 years I have been retired for 30 years now and many things have changed my suggestion would go to a proper paint store that also sells marine products.

One point to consider as you old hood could also have a lot of moisture in it,  over all it might be best to make a new one and use a product more suitable for you hood.

Keith


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## Edvet (4 Oct 2019)

polyurethane and hardwood plywood


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## zozo (4 Oct 2019)

Epoxy if not exposed to UV makes it 100% water proof. If its exposed to UV it might start to chip at the edges over time, than it needs an UV blocker added.

If your planning to build a new one and want to paint it, you could consider Multiplex Shutterboard that is pre treated with epoxy at both sides. Also called Marine Plywood. This is also waterproof but you need to coat the saw edges. And or apply silicone sealent in the corners after essambly. Than you only need to paint the outside thats in view. The inside will have the factory epoxy layer.

I made fishtanks and filterboxes from this plywood. Its absolutely waterproof as long as it aint scratched to deep.


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## idris (4 Oct 2019)

Keith GH said:


> ... go to a proper paint store that also sells marine products.
> One point to consider as you old hood could also have a lot of moisture in it,  over all it might be best to make a new one and use a product more suitable for you hood.


I'm a bit confused about "marine products". What I've read about "yacht varnish" sounds as though it may not be as waterproof as one might think. Any thoughts?

I don't have time to build a new hood at the moment. 
In the meantime, the wood in centre of the inside of the lid has certainly absorbed moisture. I was planning to leave it off to dry for a couple of weeks. Then I think I have a tin of some sort of damp treatment that's supposed to harden up wood that's suffered. Is it worth bothering with?



Edvet said:


> polyurethane and hardwood plywood


Water or oil based PU. (The ply is softwood, and in the short term will probably have to do.)



zozo said:


> Epoxy if not exposed to UV makes it 100% water proof. If its exposed to UV it might start to chip at the edges over time, than it needs an UV blocker added.


UV shouldn't be an issue - it's the insidee of tank cover that's the problem.


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## zozo (4 Oct 2019)

Take it off leave it to dry and make sure its clean and degreased inside.

Than spray it with plastidip in the color you like. 
https://en.plastidip.eu/?sg=

Plastidip leaves a non toxic rubber and waterproof coating.

Its popular in teh automitive industry, but its absolutely safe to use.


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