? about old galvanizing (casters)

I have some really old but strong casters which were once cleanly galvanized but which have corroded through the zinc in many places.
They appear basically sound, though. I am contemplating heating a strong solution of lye, then shutting off the heat (no open flame!) and putting in the casters (sans wheel, of course) with the goal being to remove all dirt, oil, grease, and, of course, zinc. Then I'd rinse in boiling water after which they should self-dry quickly. Then I could brush off any rust and prime the tops and then weld them to a plate, after which I'd paint the plate and the casters all together, then reinstall the wheels.
I believe that the lye will dissolve the zinc, releasing hydrogen. I'd do this outside, in free air, with no open flames nearby.
Anyone have any comments? Experience?
GWE
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"Grant Erwin" (clip)I believe that the lye will dissolve the zinc (clip) ^^^^^^^^^^^^^^ Wouldn't muriatic acid work better? (And probably be a little less hazardous.)
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On Tue, 23 Nov 2004 22:24:50 GMT, "Leo Lichtman"

I'm not sure which is more hazardous. But the muriatic acid will remove all the rust. Then the part will rust really fast when exposed to air. With lye the part won't rust so fast. If lye will remove zinc the way it removes aluminum that seems like the way to go. ERS
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Muratic will work, no heating nessasary. Greg
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Grant Erwin wrote: ...

I don't think so. Lye is NaOH, a reaction with zinc would give what? Sodium zinc?? No such thing, AFAIK. Muriatic acid (HCl) and zinc gives zinc chloride and hydrogen.
Bob
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Grant Erwin wrote:

OK, I took a 1-pound can of Red Devil lye, and a 10-quart stainless pot (I have an old one I use for this kind of thing). I removed the wheels from the casters and arranged them in the pot, then filled it with hot water from the tap and poured in the whole can of lye. A day later, I reached into the pan with long pliers and removed the casters and ran them under hot tap water while scrubbing them lightly with a 3M pad. Then I dried them with a paper towel and hit them with a water displacing spray to dry.
The heavy rust is completely gone. The areas that were rusted have a different look, you might say they were stained black, but there isn't any rust left. At first I thought the zinc remained, because most of the metal was still so shiny. But after looking at it dry, in bright sunlight, I now think the zinc plating is entirely gone as well. I'm going to weld them onto a steel plate and I'll know for sure then if there's any zinc left -- after spending a year doing nothing but cutting, fitting and welding galvanized angle in the shipyards, I'll never forget that smell.
I had thought what would happen was that the lye would simply dissolve the zinc. What I found out was that with the zinc ions in solution, they reduced the rust back to iron, similar to electrolytic derusting, only with no electricity. Very cool.
Grant
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