Aussiedistiller, Home Distilling, Moonshine, Home Brew

Any problem with a copper drain on a keg used to age spirit?

I donot see any problem with a copper drain on ya keg ,are ya ageing and or oaking long term or short,the amount exposed would be very small considering the volume of a 50lt keg,and if its safe for stills I can't see any negative effects,unless it was something like citrus vodka that had some acid that may react to it.anyhooo.cheers hillzabilly :handgestures-thumbupleft:

Ageing bwko. All depends how fast i drink as to how long it ages..Cheers hilzabilly

hillzabilly wrote:unless it was something like citrus vodka that had some acid that may react to it

Copper is inert to acid so no problem with an acidic spirit. The oxide that forms on copper will react with acid but that's all. Copper will only react with nitric acid but not by a normal acid/metal reaction.

One problem with drain on spirit storage is it could leak over time if its a slow leak will evaporate and will not see it happening.

db1979 wrote:Copper is inert to acid so no problem with an acidic spirit.

I think you've got this wrong, bro. High school Chemistry teaches us that copper is a metal and will react with any acidic liquid! Perhaps I'm misunderstanding your statement...?

Having said that, I don't actually know if alcohol is acidic (unless it has citrus fruits/juices added)... the copper oxide is a reaction with air and the present humidity... :think:

BUT, if it leaks, I'd agree that there is a high chance you won't know until you open the vessel to check and see the level droppped!

High school chem teacher here.

Acid/metal reactions can be considered a corrosion reaction between two different metals. Hydrogen is not often considered a metal but it is on the metal side of the periodic table and is included in the reduction potentials of all metals - it's actually the one that all other metals are standardised off.

Anyway corrosion can occur between different metals in contact with each other. Hydrogen is a more reactive metal than copper and since the reactive part of acids are hydrogen ions (think of them as hydrogen that is already reacted) then acids will react with all metals that are more reactive than hydrogen. Copper is less reactive than hydrogen and will not react. The oxide of copper is a different story since it is quite reactive and weak acids like vinegar and citric acid will dissolve it, leaving metallic copper.

db1979 wrote:High school chem teacher here.

Acid/metal reactions can be considered a corrosion reaction between two different metals. Hydrogen is not often considered a metal but it is on the metal side of the periodic table and is included in the reduction potentials of all metals - it's actually the one that all other metals are standardised off.

Anyway corrosion can occur between different metals in contact with each other. Hydrogen is a more reactive metal than copper and since the reactive part of acids are hydrogen ions (think of them as hydrogen that is already reacted) then acids will react with all metals that are more reactive than hydrogen. Copper is less reactive than hydrogen and will not react. The oxide of copper is a different story since it is quite reactive and weak acids like vinegar and citric acid will dissolve it, leaving metallic copper.

That hurt my brain a little bit :handgestures-thumbupleft:

If copper doesn't react then why do the big commercial distilleries in scotland need to replace stills after decades of running them because they become thin? :think:

Not sure, maybe from reaction with sulfur making a copper sulfide. I found a website that claims the copper sulfide then goes on to form copper sulfate which is soluble and can be washed off the walls of the still. This would cause it to thin over time. Not sure if the website is all that reliable though.

That sounds reasonable, DB. Have any members here (with a lot more 'stilling experience than me) had this thinning happen to their still?

one thing i noticed when at Sullivan's Cove was they had replaced the worm from the condenser and the old one had patches on it everywhere :think:

Also in my work i have seen copper corrode from different water types from the inside out.

You will have no problems with a copper tap ....copper does react with sulphides, but not in a bad way and as this is for post still spirits storage the sulphides should have already been stripped in the still given sufficient copper in the still itself.
Doc

DB, as a sideline... where the sulphide converts to (Cu) sulphate, will probably explain to a degree where queries have been raised regarding 'bluey tinges' in product. Makes sense to me... sulphur excess in wash converting to CuSO4... Also stands to reason that the copper is thinning in this environment, ever so slowly.

I've heard of blue floaties in product that has dipped too far into the tails but I doubt that any blue tinge could be from copper. A saturated solution of copper sulfate is about 1.5 M (at 30 degrees C) which is about 240 grams per litre of copper sulfate and represents about 100 grams per litre of copper. Colour intensity of solutions is linear so a solution of copper sulfate at half the concentration is half as intense in colour. Even 1 gram of copper in a litre of spirit is excessively high.
The first picture on the page below shows a 0.01, 0.05 and 0.1 M solutions of copper sulfate.
http://www.cuhk.edu.hk/chem/en/resources/f6resoursebk-eimg02.html
I think any reasonable amount of copper sulfate in the product would not be noticeable to the eye.

Kenster wrote:DB, as a sideline... where the sulphide converts to (Cu) sulphate, will probably explain to a degree where queries have been raised regarding 'bluey tinges' in product. Makes sense to me... sulphur excess in wash converting to CuSO4... Also stands to reason that the copper is thinning in this environment, ever so slowly.

Yer, stands to reason. Looking for actual, documented, first hand evidence. Hard evidence. Thickness measurements. Holes in columns. Holes in pots. Holes in condensers... :-B

db... thanks for the explanation, was just a thought. CuSO4 = blue..not so much...My high school Chem was 45 years ago, i am surprised i remember anything at all.Good to have a bloke with some chemistry between his ears on the site...cheers.

Kenster wrote:db... thanks for the explanation, was just a thought. CuSO4 = blue..not so much...My high school Chem was 45 years ago, i am surprised i remember anything at all.Good to have a bloke with some chemistry between his ears on the site...cheers.

:handgestures-thumbupleft:
Glad to help