Copper + vinegar and corrosion? (2024)

Decided to clean my new copper shotgun condenser and riser today.

I know you are supposed to do a vinegar run for 30 minutes without turning the condenser on. Followed by a run with alcohol one or two times for cleaning the new components.

I didn't really feel like running vinegar through my still without the condenser on was a good idea. After all, acetic acid vapours are dangerous to inhale and can result in severe respiratory irritation.

So I decided to soak my new condenser and riser in a bath of vinegar. All seemed to go well but after removing the parts from the bath they are visibly different in appearance. The copper looks discolored and sort of like its corroded.

I done some research and everything I seen basically says that you should keep anything acidic well away from copper and that vinegar directly and almost immediately causes copper to corrode.

To make matters worse. Supposedly copper when in contact with acetic acid (vinegar) results in highly water soluble and toxic copper salts being formed on the copper.

And here I am reading this after just soaking my new shiny copper parts in a bath of vinegar.

I would really appreciate some advice on this please. Because my copper is notably discolored and looks corroded after the vinegar bath.

Have I destroyed my new condenser and riser?

Rinse in water and run the sacrificial run in it... It's going to develop a patina as you use it which is good.

Got any pics for ref btw?

Cheers!
-j

Here’s the top of a copper boiler with some patina inside and out for ref.

I ran across this 60sec video awhile back. Someone here more knowledgeable can explain it more thoroughly, but whenever an acid reacts with a metal, the product will be the salt of that metal and corresponding anion of the acid. I guess the acid needs to be neutralized to stop its corrosive effect? I always thought rinsing with water was good enough.

Cleaning copper with vinegar, Salt and Baking Soda

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jonnys_spirit wrote: ↑Tue Apr 19, 2022 7:56 amRinse in water and run the sacrificial run in it... It's going to develop a patina as you use it which is good.

Got any pics for ref btw?

Cheers!
-j

I rinsed with water and done the sac run as you said. I've also done one other stripping run since then and here's the inside of my 2 inch copper riser.

Honestly it almost looks like its rusting in places on the inside. I'm not sure if it actually is rusting though or if it's just the look of the copper. Either way, the look of the copper is significantly different than before I used it.

The first stripping run that I ran through the still looks great. To be fair it's spotlessly clear. The first strip yielded 5 litres of 60% from 25 litre 13% sugar wash.

I'm just really worried about all this copper salts and copper degrading stuff. I'm just worried that my distillate could be contaminated with toxic copper salts.

Technically speaking, we are supposed to keep copper away from anything acidic including wine. So how do we get away with using it for distilling?

Would really appreciate if someone who understands all this stuff could reply here. Just so I know whether what I'm making is actually safe for drinking or not. Being new to distilling lm still overly cautious about what I'm consuming!

That looks fine and the patina will build up more. Strip runs are acidic and spirit runs are certainly high proof hot ethanol vapor so boiling acid and ethanol are pretty good for cleaning followed by a rinse. That’s all you really need or even want for cleaning.

You can strip down to about 25-40% total abv and get your low wines to a useful abv for your spirit run without having to add water.

What are you fermenting btw?

Hopefully someone will chime in about the chemistry but copper has been used for this for a long long time and is still preferred.

Wine isn’t distilled so dissolved copper and related salts stay in the boiler when distilling.

Copper does have beneficial properties for distilling too! Removing sulfides is one important benefit.

Cheers!
-j

I believe the difference would be the concentration of the solution you bathed your copper in. A light solution of vinegar Vapor, even hot Vapor, would have a less concentration and contact than a bath of the same solution. Don’t quote me on that, haven’t cracked a chemistry book in decades. If you used straight vinegar even more so (not sure if you did that).

Not to worry though. If the developed patina is a concern for you, get some citric acid (most grocery stores have it in the baking isle), and bathe your components in it. I believe the mix is two teaspoons per gallon. When the cleaning is done, rinse with plain water. It will be good as new.

On edit. Found this thread for you.

Wyododge wrote: ↑Thu Apr 21, 2022 6:53 pmNot to worry though. If the developed patina is a concern for you, get some citric acid (most grocery stores have it in the baking isle), and bathe your components in it. I believe the mix is two teaspoons per gallon. When the cleaning is done, rinse with plain water. It will be good as new.

Are you sure that's a good idea? I've heard complaints that newly cleaned copper taints the spirit. It's not something I've tried myself, having never done a spirit run on shiny clean copper.

What’s suggested is a small one time run with a 1:1 vinegar to water solution. So yeah, you had such a high concentration of acid it reacted.
Shooting in the dark here but- you probably had some dirt and/or grime on the copper so it didn’t take the copper oxide evenly thus all the discoloration.

After prolonged exposure to vinegar the copper can produce Copper acetate but I would assume that the one vinegar run wouldn’t accomplish such nonsense.

NZChris wrote: ↑Fri Apr 22, 2022 4:21 pm

Wyododge wrote: ↑Thu Apr 21, 2022 6:53 pmNot to worry though. If the developed patina is a concern for you, get some citric acid (most grocery stores have it in the baking isle), and bathe your components in it. I believe the mix is two teaspoons per gallon. When the cleaning is done, rinse with plain water. It will be good as new.

Are you sure that's a good idea? I've heard complaints that newly cleaned copper taints the spirit. It's not something I've tried myself, having never done a spirit run on shiny clean copper.

If the patina is a concern for him, yes. Start from scratch and rebuild patina in a way he’s comfortable with. In the link I gave him, there are numerous options in addition to the Citric acid method. As far as tainting the spirit, can’t say.

Wyododge wrote: ↑Fri Apr 22, 2022 9:44 pm

NZChris wrote: ↑Fri Apr 22, 2022 4:21 pm

Wyododge wrote: ↑Thu Apr 21, 2022 6:53 pmNot to worry though. If the developed patina is a concern for you, get some citric acid (most grocery stores have it in the baking isle), and bathe your components in it. I believe the mix is two teaspoons per gallon. When the cleaning is done, rinse with plain water. It will be good as new.

Are you sure that's a good idea? I've heard complaints that newly cleaned copper taints the spirit. It's not something I've tried myself, having never done a spirit run on shiny clean copper.

If the patina is a concern for him, yes. Start from scratch and rebuild patina in a way he’s comfortable with. In the link I gave him, there are numerous options in addition to the Citric acid method. As far as tainting the spirit, can’t say.

Why would the patina be a concern for him? It doesn't appear to be a concern for the old hands on this forum. Personally, I want patina in my stills and in my copper condensers.

NZChris wrote: ↑Fri Apr 22, 2022 10:36 pm

Wyododge wrote: ↑Fri Apr 22, 2022 9:44 pm

NZChris wrote: ↑Fri Apr 22, 2022 4:21 pm

Wyododge wrote: ↑Thu Apr 21, 2022 6:53 pmNot to worry though. If the developed patina is a concern for you, get some citric acid (most grocery stores have it in the baking isle), and bathe your components in it. I believe the mix is two teaspoons per gallon. When the cleaning is done, rinse with plain water. It will be good as new.

Are you sure that's a good idea? I've heard complaints that newly cleaned copper taints the spirit. It's not something I've tried myself, having never done a spirit run on shiny clean copper.

If the patina is a concern for him, yes. Start from scratch and rebuild patina in a way he’s comfortable with. In the link I gave him, there are numerous options in addition to the Citric acid method. As far as tainting the spirit, can’t say.

Why would the patina be a concern for him? It doesn't appear to be a concern for the old hands on this forum. Personally, I want patina in my stills and in my copper condensers.

Can’t say why he is, but he was concerned about it. Hopefully your input as well as others will pacify that.

Too much worry, not enough whiskey.

AppleWood50 wrote: ↑Thu Apr 21, 2022 11:38 am
Honestly it almost looks like its rusting in places on the inside. I'm not sure if it actually is rusting though or if it's just the look of the copper. Either way, the look of the copper is significantly different than before I used it.

Copper cannot rust, rust is iron oxide, no iron in copper. The dark "stuff" you are seeing is copper oxide, it's the thing copper does when it is exposed to air. Just like a penny.

The oxide layer is a protective barrier for the copper itself. This is how the Statue of Liberty is still standing after 146 years on salt water. The copper oxide itself is minimally reactive.

Copper acetate will be a blue green substance. Its highly soluble in water, give it a thorough rinse and move on.

Do your sac run and start enjoying your still. Copper is used for stills for a lot of reasons, it reacts with sulfur to produce copper sulfide, which removes the sulfur from the vapor, and is otherwise pretty well inert. Its going give you good service for a lifetime.

Ben wrote: ↑Sat Apr 23, 2022 6:34 amToo much worry, not enough whiskey.

AppleWood50 wrote: ↑Thu Apr 21, 2022 11:38 am
Honestly it almost looks like its rusting in places on the inside. I'm not sure if it actually is rusting though or if it's just the look of the copper. Either way, the look of the copper is significantly different than before I used it.

Copper cannot rust, rust is iron oxide, no iron in copper. The dark "stuff" you are seeing is copper oxide, it's the thing copper does when it is exposed to air. Just like a penny.

The oxide layer is a protective barrier for the copper itself. This is how the Statue of Liberty is still standing after 146 years on salt water. The copper oxide itself is minimally reactive.

Copper acetate will be a blue green substance. Its highly soluble in water, give it a thorough rinse and move on.

Do your sac run and start enjoying your still. Copper is used for stills for a lot of reasons, it reacts with sulfur to produce copper sulfide, which removes the sulfur from the vapor, and is otherwise pretty well inert. Its going give you good service for a lifetime.

I could be wrong but I think they perform maintenance and repairs on the statue and I doubt the frame is copper. But your point is correct copper doesn’t rust.

Also stripping runs usually clean the copper and spirit runs dull it.

hawkwing wrote: ↑Sat Apr 23, 2022 2:07 pm
I could be wrong but I think they perform maintenance and repairs on the statue a

Correct, and big commercial stills require periodic patching and maintenance, but I don't think you will ever see it on a home distillation scale. Just not enough run time.