Be part of our community & join our international next generation forum now!
Just got started reading Whiskey Science and I got to the following...
Saturday, October 18, 2014 Copper
Ethyl carbamate (EC, urethane) was a hot topic in the 1980s, as it was found to be carcinogenic and to increase during maturation phase of spirits. At the time various whiskies, especially grain or bourbon whiskies from stainless steel column stills were producing spirits with way too much EC and the concentrations seemed only to increase during maturation. It was found that copper in the ascending phase on still decreased EC dramatically and copper was (re)introduced into column stills. Adversely copper salts in the new make does catalyses the EC formation during the maturation, so most grain distillers use only stainless steel in the condensers to diminish the amount of copper residues in the new make.
Now, I also relate this to the idea that every once in a while someone produces Blue Distillate. The Blue has to come from copper sulphate in the descending path, vapor or liquid probably doesn't matter... but copper tubed liebigs...would matter. Those, like me, that believe a still cleans its self, would rarely bother to clean the descending path before a new run. I think we also live with the assumption that high ABV Ethanol and Copper do not react...this article says otherwise.
The production of ethyl carbamate has nothing to do with copper as a metal transferring into distillate. It has to do with ethanol and copper reacting to produce ethyl carbamate.
My rigs are all Stainless, but I have a ball of copper mesh in the column. It used to be at the bottom of the column, but that got hard to clean. So, lately it has been at the top just before the takeoff.
At the very least...clean the "descending" copper path just as you would the boiler before a run.
Best, think copper in ascending and Stainless only in descending path.
DAD... not yours.. ah, hell... I don't know...