I've got a tiny hairline crack in an integral fiberglass water tank
that I need to repair. So far, folks have suggested epoxy, JB weld,
polyester resin, etc., but no concensus has appeared. Any suggestions?
Any reason not to use aquarium type silicone caulk? Anything else I
haven't thought of? TIA.

On 14 Jul 2005 14:44:34 -0700, "Keith"
wrote:

I've got a tiny hairline crack in an integral fiberglass water tank
that I need to repair. So far, folks have suggested epoxy, JB weld,
polyester resin, etc., but no concensus has appeared. Any suggestions?
Any reason not to use aquarium type silicone caulk? Anything else I
haven't thought of? TIA.

With zero experience at this repair application,
here is my considered (!) view:

1) Drain water tank.
2) Paint seeping crack with alcohol.
3) Dry
4) Repeat alcohol application.
5) Ensure exterior tank near crack is keyed with emery etc.
6) Blow warm dry air into tank 1 hour before dark.
7) Paint crack with fluid grade epoxy.
8) Next day, apply epoxy tape at site of crack.
9) Pressure test tank (at low, low pressure)

Enjoy....

Brian Whatcott Altus OK

Keith wrote:
I've got a tiny hairline crack in an integral fiberglass water tank
that I need to repair. So far, folks have suggested epoxy, JB weld,
polyester resin, etc., but no concensus has appeared. Any suggestions?
Any reason not to use aquarium type silicone caulk? Anything else I
haven't thought of? TIA.

This is how I would do it, YMMV.

You don't indicate where the crack is, but assume you have access and
can drain tank as req'd.

Sand all around the crack with a right angle sander equipped with either
24 or 36 grit disk so that you have at least a 2"-3" sanded surface
around the crack.

Make sure the area is really scuffed up and is clean by sweeping up the
debris before proceeding.

Laminate about 3-4 layers of 6" wide boat tape with some good laminating
epoxy over the area making sure all surfaces are sealed.

Allow to cure at least 72 hours.

Lew