fiberglass to seal tank?

[jhilde]

Quick question here regarding plywood tanks. Can I just use tinted fiberglass on plywood as my only waterproofing or does it need to be covered with liquid rubber or epoxy?

 

[boldtogether]

I do believe that once the resin has cured, nothing else is needed...

 

[millerkid519]

Once the matting and resin is completely cured it is all you need. Keep in mind your plywood build will need to be built very rigid as fiberglass will not like to flex

 

[waynes world]

Once the matting and resin is completely cured it is all you need. Keep in mind your plywood build will need to be built very rigid as fiberglass will not like to flex

Does that not depend on the thickness of ply and fibreglass, i am starting to build a 109 long x 36 deep x 28 high tank with only 3/4 inch / 18mm ply but two lamination of 1.3lb or 600grm CSM/combination. so around 6mm / 1/4 inch thickness of fibreglass.
I have built boats with this thickness of fobreglass and plenty strong enough.

 

[spiff44]

You'll also NOT want to seal the outside. Thin paint only... unless you want to seal it as thoroughly as you did on the interior.

 

[waynes world]

You'll also NOT want to seal the outside. Thin paint only... unless you want to seal it as thoroughly as you did on the interior.

Why is that?

What usually do is give all other wood a coat of resin to seal it.

 

[spiff44]

Its just a suggestion, but unless you can guarantee that the wood never gets wet, leaving it lightly coated so that it can breath is the best bet. Otherwise it'll wick in moisture through screw holes, through the bottom when there are spills.. and if the wood is so tightly sealed it will never dry out and will rot very quickly if that moisture stays sealed in.

It makes sense to seal exposed edges that might get frequently wet like a top rim, but I would leave other sides lightly coated.

It also aids in any possible leaks. A light breathable coating will let a leak manifest right where its coming from and can dry out quickly, so you can identify the leak quickly and it won't ruin the whole tank.

 

[waynes world]

Its just a suggestion, but unless you can guarantee that the wood never gets wet, leaving it lightly coated so that it can breath is the best bet. Otherwise it'll wick in moisture through screw holes, through the bottom when there are spills.. and if the wood is so tightly sealed it will never dry out and will rot very quickly if that moisture stays sealed in.

It makes sense to seal exposed edges that might get frequently wet like a top rim, but I would leave other sides lightly coated.

It also aids in any possible leaks. A light breathable coating will let a leak manifest right where its coming from and can dry out quickly, so you can identify the leak quickly and it won't ruin the whole tank.

Good thinking that, never would of thought that way, so i mite give a coat of dansih oil on the sides, will be fine from splashs and let water out if theer is a leak

thanks for the adive.