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Old 28-11-2011, 11:27   #1
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Phosphoric Acid on Lead and Epoxy

Do they react? I ask because I need to stop a little rust on the hull located around the ballast lead in the keel. I ultra sounded the steel and the thickness is fine.
I plan to simply pour the phospho in the 1/8 inch void between the lead and steel, leave it for an hour then drain it. After it dries I'll pour the void full of epoxy. Is this reasonable?
Or, should I skip the phospho and just pour the epoxy? I dont know how to proceed here. I know I want the little void between the hull and ballast sealed up.
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Old 28-11-2011, 11:45   #2
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Re: Phosphoric acid on lead and epoxy

Simple answer, make up an epoxy spot on some cardboard and test it. I would get a neutralizer for the acid and then follow with a thorough DeNatured Alcohol rinse prior to injecting the epoxy.
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Old 28-11-2011, 12:02   #3
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Re: Phosphoric acid on lead and epoxy

Sounds like you have a 50' steel-hulled Roberts with a gap between the ballast keel and the hull. If this is the case, I would not fill the seam with anything solid like epoxy, it will end up failing and cracking out. You need a flexible material for this, I'd consider 5200. If it was a glass hull, filling with epoxy would be fine. On a steel hull the dissimilar expansion and contraction rates of the ballast keel, the hull, and the epoxy will cause failure. If you insist on using epoxy, abrade until shiny, acid etch, and prime immediately before applying epoxy. Do not apply anything to steel or lead that is cold, it needs to be warm and dry.
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Old 28-11-2011, 12:36   #4
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Re: Phosphoric Acid on Lead and Epoxy

That is true. I didn't take the time to read what kind of boat he had.
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Old 28-11-2011, 12:52   #5
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Re: Phosphoric Acid on Lead and Epoxy

Thanks Charlie, sounds like a good plan.
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Old 28-11-2011, 12:58   #6
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Re: Phosphoric Acid on Lead and Epoxy

G'Day all,

Huh? Sounded to me like he was describing the gap between lead poured into a steel keel shell and the shell itself. This gap occurs when the lead cools and shrinks.
I may be wrong here... but my keel is constructed like this and there is such a gap.

If my interpretation is right, his plan sounds ok, but I too would use some bicarb to neutralize any remaining acid followed by a good rinse before epoxying.

Cheers,

Jim
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Old 28-11-2011, 13:02   #7
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Re: Phosphoric Acid on Lead and Epoxy

Glad I posted the question here. Yes its a steel Roberts. The hull and the keel are one unit. with lead poured into the keel section. When I remove the hatch covers I am standing on the lead in the keel. The keel is made of 5/16 steel and the bottom chine is 1/4 steel.
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Old 28-11-2011, 13:06   #8
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Re: Phosphoric Acid on Lead and Epoxy

Ah, now that makes sense. I would use chockfast orange for this. If you pour acid in it, how will you get it all out? If you use epoxy I'd just pour it without putting anything else in first. Make sure it's dry...
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Old 28-11-2011, 13:37   #9
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Re: Phosphoric Acid on Lead and Epoxy

I drilled a hole in the bottom of the keel to let out rain water. Its been dry for a year now. After I phospho and rinse I'll hook up an air hose and let it blow over night with dry air. Then weld it up and pour it with __________. (fill in the blank)
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Old 28-11-2011, 13:48   #10
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Re: Phosphoric Acid on Lead and Epoxy

I'd use this. It's expensive but designed just for this sort of thing.


ITW Chockfast Marine | Epoxy Grouts, Adhesives, Repair Products, Coatings
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