Peter Hendra wrote:
On Sat, 24 Mar 2007 18:06:22 GMT, Lew Hodgett
wrote:

Peter Hendra wrote:

A fellow boater here in Trinidad has rusty steel water tanks with a
couple of pin holes in them. He doesn't have a lot of money but does
have a supply of cold tar epoxy.

Question: Should he drink the water from the tanks if he paints them
internally with said cold tar epoxy? Are there any isocyanates or such
that will leach into the water that would be harmful to his health.

If so, what would be the most cost effective (cheapest) internal
coating?
Not a good idea to use coal tar epoxy on potable water tanks.

SFWIW, I used CTE on my holding tank.

There are resins specifically made for coating potable water tanks.

They are known as tank resins.

I'd use two (2) coats, white followed by some other color.

SFWIW, that's what I did based on the suggestion of the supplier.

Makes it easy to see if you missed anyplace.

Have fun.

Lew

Lew,
weren't you a contributor to the Yacht-L boating news group about 10
years ago? If I recall correctly, you were building a rather large
vessel.

Yes.


Please enlighten me. What is "CTE"

coal tar epoxy

Also, as you seem to know your stuff, does anythbing harmful leech out
of tanks constructed with ordinary epoxy resin? When I built this
boat I made my diesel and water tanks from glassed over plywood. I
just used the ordinary epoxy resin I sheathed the hull with.

Built my tanks the same way.

My supplier of epoxy laminating resin suggested talking to my coatings
supplier when it came to tankage.

Laminating resin contains no VOCs.

Tank resin, AKA: "high build primer" definitely contains VOCs.

As a high build primer, it provides the tie between the laminate and the
L/P paint used to get a high gloss "yacht finish".

As a tank resin, it is approved by US gov't for use in tanks.

Never got deep enough into it to get all the techie answers, just did
what was suggested by the pros in the business.

As far as your friend is concerned, think I would investigate the usage
of bladder tanks inside the existing steel tanks.

My guess is you try to repair existing tanks, might get one year, if lucky.

A lot of work and high risk of early failure IMHO.

Lew




We have lived on-board and cruised for about 14 years now and drunk
the water from these tanks filtered by a standard household granulated
carbon cartridge filter.

cheers and thanks for the advice
Peter Hendra