Join Date: Apr 2006
Thanked 179 Times in 176 Posts
Rep Power: 13
Re: Keel Fix help
DrB, one doesn't apply a barrier coat over a lead keel, since there is nothing to "barrier". The lead doesn't give a damn what kind of water it is immersed in.
OTOH one certainly would apply a fairing coat over a lead keel, to provide a smooth surface. And antifouling paint over that. But then you'd be looking for a FAIRING product, not anything sold as a barrier coat.
Lead forms a thin skin of lead oxide upon exposure to air, and that thin layer of lead oxide is what comes apart and lets the coatings peel off. The trick to good adhesion is a somewhat messy process, you want to clean the lead, and then as you apply the next layer of epoxy fairing compound, scrub it in with a wire brush or metal mesh pads, so that you are scraping away at the oxide coating and allowing the bare lead to bond with what you are applying.
That may take four hands, i.e. yours to apply the goo and scrub it in, and someone else following you to smooth it off. But if you get that first coat scrubbed in so it has bonded with bare lead instead of an oxide coating, it should stick very nicely. Especially if it is an epoxy.
How much fairing you decide to do on the lead, rather than on the filling/fairing layers over it, is something else again.