safe fresh water tank caulking

[ron ll]

I have to alter the shape of an existing epoxyed plywood freshwater tank built by the previous owner. There will be a mating of a horizontal top piece to the top edge of a vertical baffle that I will not be able to access after assembly to epoxy. Is there a caulking/adhesive that is drinking-water safe, tasteless after cured, and compatible with epoxy?

[sdowney717]

www.Sanitred.com (http://www.Sanitred.com) makes permaflex an approved food safe inert polyurethane liquid adhesive sealer.
Like a thick paint before curing, so it can be painted on surfaces and is waterproof.
But I dont know if this is appropriate for your use.
such as if you are looking for something in a cartridge tube.

[Gary E]

Seems to me that if permaflex is an approved food safe coating, all surfaces could be coated with it then a "O Ring" seal could be used between the tank and the lid to close the container. This way it could be inspected most any time.

[ron ll]

Thanks, that might be worth a look. However, I am very embarassed to say I overlooked the obvious before I posted the original question. I was thinking in terms of something like 5200. But I woke up in the middle of the night with a Duh!! Just use a bead of thickened epoxy. Keeps the water out, doesn't taste funny, and best of all, its compatible with epoxy! tongue.gif

[Rick Clark]

ron ll

Hey do you have a large clean out portal on the top of the tank? and is it removable? I put one in mine to be able to clean the tank once a year and put some Clorox in it for a good cleaning. But I built it ply wood and 4 layers of fiberglass inside and out. I then mixed up a batch of resin and pored it onto the sealed top on the inside and kept turning it from side to side and let it run on all the seams took about 2 hours of turning till it set. But I have never had a leak, lucky me :D

[ 11-27-2005, 06:13 PM: Message edited by: Rick Clark ]

[ron ll]

Yes, this tank has two large round inspection ports in the top. Also, it is a quite large tank that is built into the boat, so rotating it to spread the resin is not an option other than maybe rolling and/or pitchpoling the boat. smile.gif

However yesterday I cut the tank open in the shape of the new footwell I will install, and I was pleasantly surprised at the condition of the inside of the tank. It is epoxy over plywood with glass strips in the corners. The tank was very clean and the wood thru the epoxy was clear and bright. There was a slight residue deposit at the high water line, kind of like a ring in a bathtub, but very minor. Altho I usually filter the drinking water, I would have no problem drinking the water straight from this tank.

[Gary E]

I understand the need to make plywood tanks, but for a water tank you will drink from, I like my SS tank. I really like the first drink from it in the spring after last fall's winterization removes most of the water and the remaining was diluted with a gallon of gin. smile.gif

[Hugh M.]

Ron:
Epoxy itself is not rated as food-safe. There are food-safe coatings that are available and can go on top of the epoxy. This is what I will be using on my epoxy-clad tanks, though I haven't chosen or used one yet.
Maybe others have?
-Hugh

[kc8pql]

Sounds like you've solved your own problem but, for future reference, there is an FDA approved silicon sealer made by GE. The easiest place to find it is a good aquarium store. It's used to seal fish tanks. Look for "FDA approved for food contact after complete curing (7 to 14 days)" on the tube.

[ron ll]

I understand that epoxy may not be rated "food safe" by the FDA. But I suspect that may be slightly different than "actually" safe. Would anyone considered it dangerous to use in a potable water tank? Are different brands or types of epoxy different in this respect?