Issues With Removing Galvanisation
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Joined: June 18, 2018
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Issues With Removing Galvanisation
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Posted on Thu Jun 20, 2019 1:41 am
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Hi, about 8 hrs ago I put my galvanized chainmail shirt into a tub of vinegar to remove the galvanization. Unfortunately, there seems to be a problem emerging.

The vinegar has dissolved pretty much all of the zinc plating off of some parts of the shirt, but seemingly has done very little to other parts. Specifically, it has only dissolved the zinc from the sections that I have recently added to the shirt (within the past month or so), leaving the parts that are older mostly untouched. (I took about a 6 month break, so there is a very clear demarcation between the "dissolved" and "not dissolved" sections)

Have the "older" parts developed an oxide layer that is protecting it from the acid? Or could there be a film of oil left from me handling it?

I've tried scrubbing the unaffected areas with a wire brush, as well as scoring them with a piece of sandpaper in hopes to get the reaction started, but with no success.

Will the acid begin to dissolve the steel in the places that the zinc is no longer covering it? Or will it be so slow that it will be negligible?

Any ideas would be extremely appreciated. I really don't want to ruin this shirt that I've spent so long making. Thanks!

Joined: March 27, 2002
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Posted on Tue Jun 25, 2019 9:45 pm
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Oxidation is exactly what happened to that zinc on the older mail. It's more or less a sacrificial metal, controlling corrosion of some more vital metal by taking it all. You see this sort of thing on boat hulls and propeller shafts to keep them sound -- and regularly replace the zinc during the maintenance cycle. The zinc has ended up shielded from the vinegar.

Brick cleaner (dilute HCl) may answer your need; hydrochloric acid is a more powerful reagent than vinegar, while still not too frightful to handle -- rubber gloves would be about as much as you'd ever need. The usual react/rinse/neutralize/rinse again cycle.

HCl or the more ferocious H2SO4 will react the steel also, though slower than the zinc. They bubble strongly reacting the zinc -- liberating hydrogen in the bubbles -- and visibly more slowly when they start biting the steel beneath; that's when you pull it out and neutralize. H2SO4 calls for more caution handling it -- gloves definitely.


'The Minstrel Boy to the War is gone...'

Joined: June 18, 2018
Posts: 12
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Posted on Tue Jun 25, 2019 10:48 pm
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I ended up getting it to work a couple days ago. What ended up working for me was taking it out and rolling it in a bucket of sand for a while. After putting it back in it worked very well.

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