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witzgall · 12-01-2014, 05:16

HI all,

Gossamer's main water tank is fiberglass. When we bought her, the tanks were dry, and some small blisters were evident, weeping the usual blister goo. So we would like to coat them with a food grade epoxy. I have read about this several times, but I am having a hard time nailing down a source for anything that people have actually used in this application.

So, if you have, or know somebody that has coated the insides of their water tanks with a food grade epoxy, please share the (USA) source!!!

Thanks,
Chris

tamicatana · 12-01-2014, 05:18

Contact West Systems:
West System Epoxies

I'm sure they have an answer

--on second thought, why not just install a bladder?

keepondancin · 12-01-2014, 05:23

I tried talking to West about that, and at the time, they wouldn't commit to it being safe, it was untested. Try again, also try MAAS epoxy, or System Three.
There properties make them a little more user friendly, no amine blush, etc., so they may be more receptive. A Google search will reveal sources, but they seem to be much less consumer friendly.

pressuredrop · 12-01-2014, 05:33

this is kind of a tricky one, researched it a bit myself and here is what i found…

re: west system, the nasty stuff is in the hardener not the resin, while they do not whole heartedly endorse using it for drinking water tanks, they say if you do to mix it slightly resin rich, if it is hardener rich the extra hardener in the matrix will leech out over time and that is some bad stuff...

there are a number of commercially available coatings that are used in giant municipal water tanks etc.. the caveat with these is that their recommend applications involve a very small ratio of surface area to gallons of water in the tank (think hundreds of thousands of gallons)… that ratio gets very skewed in a small tank….

take it for what its worth
Ben

pressuredrop · 12-01-2014, 05:35

james baldwin Atom Voyages - Home has done some f.g. water tank retrofits over the years, if you email him he will happily share the products he's used...

chuckr · 12-01-2014, 05:40

we had a leak in our fwd plastic water tank and got some food grade 2 part epoxy paint that did the job in trinidad - but gosh i do not remember the name - if anyone is in trini i got from the guy who makes the watermakers down the road across from the marine school -
it did the job

Capt Hugh Wilde · 12-01-2014, 05:52

Buff Devoe 233 H is Certified to NSF/ANSI 61 and is suitable for coating potable water tanks.
Check out with a Devoe distributor and they can help you. Let them spec the product, but I have used 233 in the past for this duty.

georgelieber · 12-01-2014, 06:02

Bar-Rust 233H in the usa. NSF Certified for drinking water.

http://www.duspec.com/DuSpec2/produc...t=Get+Document

pressuredrop · 12-01-2014, 06:16

^^^ from product spec sheet:

"For use with tanks greater than 200 gallons and pipes greater than 14 inches not exceeding a surface area to volume ratio of 131 sq cm/L only when mixed in a ratio of 4 parts base to 1 part converter, by volume."

not saying it won't work, just saying...

Capt Hugh Wilde · 12-01-2014, 06:17

Quote:

Originally Posted by georgelieber

Bar-Rust 233H in the usa. NSF Certified for drinking water.

http://www.duspec.com/DuSpec2/produc...t=Get+Document

But you have to use the Buff color, something in the pigment. But 233H Buff is the product you seek. They even have a special thinner to be used with it for drinking water.

HopCar · 12-01-2014, 07:17

Somay in Miami makes technical coatings some of which are certified for potable water.
http://www.somay.com/pdf/Potable-Water-Systems.pdf

Capt Hugh Wilde · 12-01-2014, 08:52

Quote:

Originally Posted by pressuredrop

^^^ from product spec sheet:

"For use with tanks greater than 200 gallons and pipes greater than 14 inches not exceeding a surface area to volume ratio of 131 sq cm/L only when mixed in a ratio of 4 parts base to 1 part converter, by volume."

not saying it won't work, just saying...

Used it for years in smaller tanks haven't killed anybody yet. The best thing to do is coat it and wait several weeks for it to cure and air out the tank while drying if possible.
We always then fill it and pump it dry a couple of times before putting it in service.

Capt Hugh Wilde · 12-01-2014, 08:55

Quote:

Originally Posted by witzgall

HI all,

Gossamer's main water tank is fiberglass. When we bought her, the tanks were dry, and some small blisters were evident, weeping the usual blister goo. So we would like to coat them with a food grade epoxy. I have read about this several times, but I am having a hard time nailing down a source for anything that people have actually used in this application.

So, if you have, or know somebody that has coated the insides of their water tanks with a food grade epoxy, please share the (USA) source!!!

Thanks,
Chris

Grind out the blisters and fill with epoxy and silica and sand smooth before applying the Devoe 233 H. Make sure the blister areas are dry before you do so. Lightly sand the inside of the tank and clean well before coating.
I would coat it, wait a couple of days, and apply a second coat. That would be my fix.
It sounds like you have good access to the inside of the tank, and that is good.