Re: [Cal_Boats] Barrier coat paint (Chris)

Donald Dutton2008-03-20 17:56 UTC

We had a sailing club in Seabrook, TX that was a concrete highway structure with a block clubhouse built on top. The iron re-bar that was inside the concrete got wet because we never sealed the concrete and the rusting re-bar cracked the concrete that was two feet thick! The solution to your problem has to be; First) find the source of the water to the keel and fix the leak, Second) completely expose the wet parts of the keel and dry thoroughly, Third) seal the iron with a barrier, Fourth) rebuild the fiberglass structure that encapsulated the keel, and Fifth) bottom paint the fiberglass as normal. Epoxy sealing of the repaired fiberglass encapsulating the keel would help to guarantee that there is no route to the iron for water to travel through the fiberglass. Don Dutton, 1986 Cal 33, "Quantum Evolution" PS the solution to the clubhouse problem was to freshwater wash the whole structure, seal the building in plastic sheeting with de-humidifiers running (for two weeks) to dry out the structure, fill the cracks in the concrete with an injected epoxy, and then seal the concrete with a vapor barrier paint -- we used ThoroSeal, but there are other brands available -- just in case any of you are involved with a concrete structure near the water. We had a man on our board from Parker Concrete in Houston who knew all of the appropriate contractors needed to do the work. From: Chris Campbell <cl… [at] charterinternet.com> To: Ca… [at] yahoogroups.com Sent: Thursday, March 20, 2008 10:21:36 AM Subject: Re: [Cal_Boats] Barrier coat paint ira reba wrote: I own a Scanmar 33, a Swedish built sloop. It has a cast iron encapsulated keel with some rust bleeding through. I intend to sand it down and add 2 or 3 coats of barrier paint. Can anyone recommend a brand/type? I always see "bottom coat" paints (ablative, hard, etc.) advertised but I know this is not the right kind of paint for what I want to do. Any suggestions? Ira: You need some sort of proper barrier between the iron and theantifouling paint, which usually contains copper. Copper + iron =battery. I have used Pettit's Rustlok on my iron keel. Follow the preparationand application instructions carefully. It works well for me. Othershad suggested that they preferred another primer for iron. By the way, I understand "encapsulated keel" to mean the ballastmaterial is inside a fiberglass shell, usually an integral part of thehull. If that's the case, if your iron is inside fiberglass, you'vegot to stop the rust because iron oxide occupies more volume thaniron--it expands as it rusts. Chris Campbell