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Muriatic acid tanks for stripping galvanize are hard to come by

I'm searching for a means to remove the galvanized coating from an animal panel. Maximum size is 48" x 48". Metal coatings companies tell me that I'd "kill" their muriatic acid ⇦ this on eBay or Amazon [affil links] tank if they were to dip them for me. What's the lifespan of the acid once bottle is open? Any ideas for a shallow tub 50" square?

Randy Nelson
hobbyist - St Joseph, Michigan, USA
March 9, 2009

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March 11, 2009

Lifespan of the acid once the bottle is open doesn't come into it - left to its own devices, it remains the same but will slowly evaporate if you leave the cap off the bottle.

But when you use it to strip zinc from a galvanised item, the reaction between the zinc and the hydrochloric acid converts the acid to zinc chloride and hydrogen gas. The acid is destroyed by the reaction. The hydrogen gas isn't a problem (it just floats away into the air), but if the bath of hydrochloric acid is for a use where zinc contamination would be a problem, then clearly that particular acid bath can't be used for a zinc stripping job.

If you are near a hot-dip galvanising plant, you might get them to strip the item, either in their inhibited acid pickle bath, or in their flux bath (which contains zinc anyhow). An inhibited acid bath will strip the zinc without dissolving the underlying steel. Uninhibited acid will get stuck into the underlying steel once the zinc is removed from any area.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.

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A plastic kiddie pool would do.
The amount of zinc that you can strip depends on how slow you can put up with, on the practical side. On the theoretical side, check out a chemistry book, balance the equation and plug in the numbers.

James Watts
- Navarre, Florida
March 11, 2009