Preventing copper oxide

[neil]

I wandered what methods you guys use to prevent copper oxide from getting in your home distillate. If you would use a full copper pot still, and you can dismantle the pot and the lyne arm easily, what is the right way to go to clean you pot still before use. When you leave your still for quite some time, copper oxide builds op inside the still leaving a greenish glance on the surface. I read about citric acid and acetic acid. Only that last one give a nasty taste so one needs a cleaning run before distilling a wash. With citric acid that is luckily not the case but you need a whole lot of it to fill your still with. (Which concentration of acid is best?)

Any suggestions?

[NZChris]

I've never had oxide in my still or condenser

[DAD300]

Best practice is to have as much copper on the ascending side as possible and no copper (stainless) on the descending path. Almost all of the copper sub agents can not be carried over in the vapor.

See post in my signature.

Clean your copper with citric acid or lemon juice.

[rad14701]

There are many ways to protect copper during long term storage but a clean dry still should not form copper oxide even over many months... You could coat the entire rig, inside and out with a thin layer of food grade oil that could be removed with a short quick boil-up and wipe-down, for one example...

[corene1]

So far I have been fortunate enough to not have any oxide build up. After a run when the abv of the output is low, I turn off my cooling water and let the condenser steam for 30 seconds or so then turn the heat off. After things have settled down I disconnect the condenser and blow a little bit of air through it. This will dry it out and the tails will have left a slight oil film in the condenser. I also empty the pot and thumper while it is warm and dry them out well. The heat will help them dry all the way. If I am going to store them for any amount of time , I take a rag and soak it in foreshots and wipe the still down inside and out then dry it well. This leaves a trace film on the surface of the copper and will absorb any water that may be left. Then when I use it next time the fores will clean any residual film left from cleaning and this is discarded anyways. This is just what I do though.

[MDH]

The solution is simple, make your condenser out of stainless steel. Copper oxides within the still actually act as a catalyst and should be left alone.

[neil]

@corene1: thanks for the heads up. I will try to use them in the future (though my still is tot deep to clean with a rag all the way)

@MDH: Why should they be left alone?

After a lot of effort I now have a copper lyne arm and it has some copper oxide inside of it. Especially on the seems. I was wandering if I have to clean the inside of the lyne arm as good as the still itself. Vapors come in contact with the oxide if it is not removed. And copper oxide is supposed to be bad for you.

Because the lyne arm is soldered all the way it has no leaks or open seems. So it is possible to pour a citric acid solution into the arm and keep it there to soak for a while. Will this do the trick? And do I have to apply the same method for the kettle itself? (22 gallon still)

[myles]

After doing construction or repair work on a copper still or vapour path you should do a deep clean with acid or vinegar. This is to get rid of flux and solder residues.

To be honest though after that it shouldn't need deep cleaning. Copper oxide on the inside of the still is good because raw copper leaves a taste in the product. This is NOT green though it is a slight brownish patina as opposed to the almost pinkish colour of fresh raw copper.

Any greenish colour is a combination of copper chlorides, sulphates, sulphites and carbonates.

[corene1]

I thought this might help. I also thought the greenish coating was copper oxides so I have been reading a bit. Hope this is helpful.
http://www.tech-faq.com/what-causes-cop ... green.html" onclick="window.open(this.href);return false;" rel="nofollow

[NZChris]

I've never had oxide in my still or condenser

I got interrupted by the dentist, sorry.

Fusels coat my still head and condenser and protect them from oxidation. The worst thing you can do is get hypo about cleaning your still after a run. Let the fusel coating protect the copper and you shouldn't see oxide unless it is months between runs and you do something else wrong too, like leaving it wet/humid, leaving traces of acidic wash in the boiler, the kinds of things that you would expect to give you problems.

[neil]

At what strenght should the solution be? I'ge got citric acid powder, but how many should I use for 1 gallon or litre to achieve a proper working mixture?

[bearriver]

1 or 2 tablespoons per gallon cleans up copper mesh from my experience. The required quantity will vary depending on the buffering capacity of the water, as will all pH adjustments.

Why are you cleaning the copper? I don't fuss with it.

[neil]

1 or 2 tablespoons per gallon cleans up copper mesh from my experience. The required quantity will vary depending on the buffering capacity of the water, as will all pH adjustments.

Why are you cleaning the copper? I don't fuss with it.

I thought that the green stuff shouldn't be in your still, let alone in your spirits.