LouieIV

Vinegar to remove Galvanized coating.

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So I'm using vinegar to remove some galvanization. I was wondering what kind of precautions I should take.
Are toxic fumes released?
Is the residue left in the vinegar harmful to touch? Obviously I don't want to drink it.
I assume that if it were to dry out it would be harmful to breath.

By the way the "Zinc, Cadmium, Hydrogen Fluoride and other toxic compounds" seems to be broken. At least I can't seem to open it.

Thanks,
LouieIV

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So I'm using vinegar to remove some galvanization. I was wondering what kind of precautions I should take.
Are toxic fumes released?
Is the residue left in the vinegar harmful to touch? Obviously I don't want to drink it.
I assume that if it were to dry out it would be harmful to breath.

By the way the "Zinc, Cadmium, Hydrogen Fluoride and other toxic compounds" seems to be broken. At least I can't seem to open it.

Thanks,
LouieIV


It'll produce hydrogen gas and zinc ions. Hydrogen is flammable, but vinegar is a weak acid (so you'll produce H2 slowly), and the zinc isn't all that thick. So absent some really odd circumstances, I can't see any real danger there. The ionic zinc is nothing to freak out about, either. Galvanized pipes leach zinc into the water supply 24/7/365. It's not a big deal. I wouldn't feel badly pouring it down the drain. Of course if you were doing this on an industrial scale, it might be different.

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Hydrogen is released, and aerosol vinegar becomes a hazard if your container is open. I use a container with a lid, and put a string down so the lid doesn't seal tight. I have set the lid on a rag stretched over the top too. Might be good to leave it outside.

The remaining zinc laden vinegar should not affect undamaged skin. I still wear rubber gloves though, or I use tongs.

Wash in ammonia and water, it seems to work better than baking soda. I don't use much, about 1 oz cheap sudsy ammonia to 1 gallon water. I then wash with dish soap and water with a stiff brush. Parts seem to not rust for quite some time for me after this treatment.

Phil

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Thanks for the info guys.

Don't go huffing the fumes or lighting a match right over it. Don't rub the stuff all over open wounds. Keep outdoors or well ventilated.

But relatively safe compared to burning it off.

Hopefully my 1-1/2 x 6 nipple will be clean by morning so I can get my forge put together and lined tomorrow.

-LouieIV :)

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Apologies for resurrecting this oldie, but I couldn't find my answer elsewhere and this seemed like a good spot to ask. 

I need to remove the zinc from about a dozen, 1 1/2 inch washers so I can tack weld them together.  I figured I'd soak them in vinegar since that process was mentioned and I happen to have vinegar available as opposed to HCl or muriatic acid.  My question is, how long do I need to soak them (until the zinc is gone being the obvious answer) and how do I know when the zinc has been removed?  Will the washers be visibly different than when they went in?

 

Thanks!

 

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Zinc tends to be more of an ash gray when not shiny. Steel will be much darker silver color, "steel gray" they will turn dark, almost charcoal gray when the vinegar is done with the zinc.

If you're not sure, rinse and neutralize them with baking soda, rinse and dry. Leave them out for a while they'll start rusting almost immediately if the zinc is gone.

Frosty The Lucky.

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 Here's a dumb question........What do you do with the vinegar when your done with it?                Dave

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1 hour ago, Dave51B said:

 Here's a dumb question........What do you do with the vinegar when your done with it?                Dave

Not dumb at all. It's not toxic but don't make salad dressing with it. Dilute it or neutralize it with baking soda and spread it out. I prefer diluting it with water and spraying it, our soils tend to be alkaline so sweetening it up doesn't hurt a thing and zinc is good nutrients.

Neutralized and it's a salt but diluted not toxic just spread it out it'll be fine. Heck probably fine going down the drain even into a septic tank. I'd ask a septic pumping company before pouring a lot down though.

Disposing of muriatic, etc. acids are another matter you should ask the local authorities but do so anonymously or they'll be on you like flies on . . . a picnic sandwich.  ;)

Frosty The Lucky.

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If one is in doubt about the complete removal of the zinc coating. Let the metal soak in the vinegar solution, for a while then dispose of the liquid and pour some fresh vinegar into the container. Vinegar is not a strong acid. It's usually just a three to five % solution of acetic acid in water and it is relatively cheap.     SLAG.

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Frosty's comments are spot on.  Plus....when they quit bubbling, the zinc removal should be finished.  For washers, it takes me only a couple of hours at the most.  Keep stirring the mix to assure complete removal.

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I buy unplated "plain finish" fasteners and threaded rod at the local Fastenal stores.  There are four of them within driving distance.  They also will ship from their web site to your shop or home if that is preferred.  I tried the route of removing plating with vinegar once and decided it was not worth the time and effort. They are manufacturers of fasteners, so if you set up a in-store account they will likely give you the wholesale discount.

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On 4/14/2016 at 9:27 PM, Frosty said:

Not dumb at all. It's not toxic but don't make salad dressing with it. Dilute it or neutralize it with baking soda and spread it out. I prefer diluting it with water and spraying it, our soils tend to be alkaline so sweetening it up doesn't hurt a thing and zinc is good nutrients.

Neutralized and it's a salt but diluted not toxic just spread it out it'll be fine. Heck probably fine going down the drain even into a septic tank. I'd ask a septic pumping company before pouring a lot down though.

Disposing of muriatic, etc. acids are another matter you should ask the local authorities but do so anonymously or they'll be on you like flies on . . . a picnic sandwich.  ;)

Frosty The Lucky.

Good info. Thanks, Frosty.

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Muriatic acid is solution of about 30% hydrochloric acid in water. It can be neutralized by any base. Baking soda will work and  lye would work faster. But be careful neutralizing using either chemical. The reaction is very vigorous producing a lot of carbon dioxide gas which could send the acid into the air. Use skin, eye, and vapor protection. And do it outside away from people and animals. Better yet stick with vinegar instead. (which is a 5% acetic acid solution) in water.

Highly diluted zinc acetate salt (the product of vinegar and galvanized steel). can be put on a garden that is alkaline. But spread it around so the garden does not become too acidic. Also heavy deposition of zinc could also affect plants.

Humans do require zinc. but in very small amounts. They can be purchased at the drugstore. (but the chemical in them is not zinc acetate but is zinc gluconate,) Which is the glucose sugar salt of zinc.

But I digress big time.

SLAG.

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15 minutes ago, SLAG said:

But I digress big time.

SLAG.

No, no -- that's very informative. Considering some of the tangents we go off on here on IFI, that's pretty darn on-point.

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Hammer Person,

"pretty darn on point",

On the point of a red herring or on the subject.

I am easily confused

SLAG..

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When neutralizing with soda, do you make a slurry and "paint" the parts with it or just dump some in the pot you are soaking in?

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Dear Square,

After a part is soaked in an acid bath, pull the part out and flush it with a lot of running water. Then put it into a dilute solution of water and a base. Baking soda will do nicely.

There is no need to neutralize the original acid bath solution that you placed the part In, in the first instance.

I hope that is clearer than mud.

Regards, and happy chemistry.

SLAG.

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On 4/14/2016 at 7:47 PM, Frosty said:

If you're not sure, rinse and neutralize them with baking soda, rinse and dry. Leave them out for a while they'll start rusting almost immediately if the zinc is gone

Thank you! That little bit was Exactly what I needed!

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If you are not certain that all the zinc has been attacked,  and totally removed, by the vinegar. Flush the metal,  and have another go with fresh acetic acid.

Vinegar is cheaper than a new set of lungs.

I have, on occasion, repeated the procedure two more times.

Cheers,

SLAG.

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Slag, your detailed explanations involving the various toxic metals, acids and bases is properly explicit and exact.  Your knowledge of the right processes to deal with these various issues is extensive.  Thanks. 

One thing I would like to add about heavy metal coatings in general and galvanize in particular, is that we as end users or workers with products involving heavy metal coatings do not "Know" what exactly the coatings are made of.  Assuming that they are only zinc, even when that may be the only metal mentioned on the packaging, if there is any, is very dangerous, since the whitish powdered oxides of all these metals look very similar.  Moreover, it is not safe to assume that for-profit companies dealing in products that have coatings on them, will always be ethical in choosing the sources of these products.  Just my 2 cents.

I have worked in chem labs professionally, doing wet analysis for traces of lead in "Food-grade" sulfuric acids, as is government mandated, because 450 parts per million of lead4 oxide, ingested by a human being, will over a short period of time kill him.  And the lead does not get flushed out of a living person.  So ingestion of it is cumulative.  As an example, handling weathered galvanized pipe barehanded for an hour, then eating a sandwich without thoroughly washing the hands in soapy water, then rinsing, will allow ingestion of several hundred parts per million of heavy metal oxides.  I cannot in good conscience have not gone into this rant, so cannot say sorry for going on about this, because in fact the very devil is in the details.  If you've read all this, thanks.

I've got 3 historical events I can relate on this topic that goes back 1000 years, each of which describes the horrifying deaths of 10s of people.

 

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Zinc isn't a heavy metal and is soluable so excess will flush from the body. It's a necessary nutrient without which our skin wouldn't be flexible among other things. It's also one of the cheapest and easiest to plate metals around.

That said the warning to NOT TRUST plating is exactly right. Just because it "looks" like galvy doesn't mean it is and there are some seriously toxic metals plating seemingly inocent things. Heck other stuff on and in metal.

A couple decades ago we were staying at a roadhouse working a job and the wood stove was the most effecient heater I've ever run across. The problem I discovered from a lineman staying there was the wood stove was made from an old transformer box with cooling fins on 3 sides. Worked a treat but it was taken out of service because it was filled with PCB heat transfer oil. He ate in his room, only stopped in for a beer after work and to settle his bill, wouldn't hang in the common room nor eat in the restaurant. He said he was amazed the owners were still alive.

Frosty The Lucky.

 

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