Comments on: Strip Zinc with Citric Acid

By: tedwriter

tedwriter — Thu, 28 Feb 2013 00:38:36 +0000

It’ll go even faster if you toss in a penny. Copper catalyzes the reaction between the acid and zinc. In fact, cut two tiny nicks in the rim of the penny (post 1984) and the zinc core will dissolve leaving a very thin copper shell.

Should work with other acids, including vinegar, but some will take longer (and be potentially safer due to the dispersal of the hydrogen gas).

By: wilsonmv

wilsonmv — Tue, 26 Feb 2013 20:38:53 +0000

To add to the caution notes, please perform this operation in a well-ventilated environment. The bubbles you see forming are hydrogen gas…explosive in an enclosed area like a small basement shop. Unless you are stripping massive quantities of hardware, it’s probably not a problem, but people should be aware.

By: micksandine

micksandine — Tue, 26 Feb 2013 17:51:27 +0000

Look in the water softner section of the store. Some of the rosin bed cleaners are citric acid.

By: micksandine

micksandine — Tue, 26 Feb 2013 17:49:14 +0000

I found the citric acid product as a rosin bed cleaner for water softners. It is dry and stores easily. You might have to experiment with the mixture. I used 1 part dry citric cleaner to 2 parts water.

By: jagriz

jagriz — Fri, 22 Feb 2013 13:33:59 +0000

I see by quickly writing “soda water” rather than “baking soda and water” I’ve caused confusion. At no time was the intent to use CO2 and water .

By: Christopher Hawkins

Christopher Hawkins — Thu, 21 Feb 2013 21:42:32 +0000

I believe that citric acid solutions have been neutralized with sodium bicarbonate solutions safely many thousands of times. However, as an organic chemist with several years of using citric acid on an at least weekly basis, you want to be careful if you neutralize citric acid.

When using concentrated citric acid and neutralizing it with a sodium hydroxide or ammonium hydroxide, the heat generated can very easily be enough to make the water boil. If you want to neutralize citric acid with solutions of baking soda, dilute them so that the % solids of both the citric acid and the baking soda is <2%. Using baking soda would be problematic because of the CO2 generated. If you were to take a concentrated citric acid solution and add solid baking soda to it you could end up with a very hot, foamy, acidic mess. If your waste water is treated by a public or private waste treatment facility, just pour it down the drain and flush with water. They will remove the zinc from the waste water. If you are on a septic system and want to be super ecofriendly, I recommend you let the water slowly evaporate, put the residue in a empty plastic container, and put it in your regular trash.

"Soda water" is not a solution of baking soda in water. Soda water is made by adding CO2 to water. Soda water is acidic and will not neutralize citric acid.

The rate of corrosion of citric acid solutions on steel at room temperature is low enough to not be an issue in most cases. I don't know specifically about cast iron or copper pipes.

By: chrismobley

chrismobley — Thu, 21 Feb 2013 21:21:48 +0000

I have also always used white vinegar. Great tips. Thank you for sharing.
Chris Mobley
http://www.cmobleydesigns.com

By: robert

robert — Thu, 21 Feb 2013 16:43:18 +0000

Cris:

I get where you are coming from. Lots of trade offs in this life. Everybody should be comfortable with their choices. Just wanted to provide some grist for the mill.

By: Megan Fitzpatrick

Megan Fitzpatrick — Thu, 21 Feb 2013 02:07:38 +0000

For the record, I’d much rather observe you employing the citric acid method.

By: Christopher Schwarz

Christopher Schwarz — Thu, 21 Feb 2013 02:01:30 +0000

OK, not trying to be pissy. Promise.

I used to torch the zinc and then pee on the hardware. Honest. Is that worse for the environment? Seriously. Because I’d be happy to go back to that.

What I would prefer (and I’ve said this before) is that I could get hardware without the zinc. I usually buy from BlacksmithBolt.com, but sometimes I need the hardware store stuff quick.