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Copper eats sulfur eats copper


Jester

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Folks,

I wanted to open for discussion/debate the topic of copper and its use in distilling. I have done some investigation during my work with distillation eqiupment. Wikipedia has a very interesting summary on the theories and answers to the questions in my mind. Is copper neccessary for distillation? How much and where? Is there an alternative method to desulferise your product? Is there a discernable amount of sulfer in the "typical" mash? Are consumable copper alternatives viable?

Many questions, of which I have answered some in my mind to a level in which I am comfortable. I have had samples of product that had never come in contact with copper-which were very smooth. not to say I am an expert- I am not. I know what I like and that is about it. I know what I don't like and am not afraid to spit out crap even if 100 experts say its great. I drink what I enjoy, I think everyone should. in the wiki descriptions is stated that copper will end up in the waste product to some degree. it also states copper will need maintenance. I know most still builders will engineer this factor in and build out of heavier gauge material as an answer to a short term failure. you will pay for this insurance. this is the link to some reading... http://en.wikipedia.org/wiki/Still

I prefer stainless steel. I do not negate the usefulness of copper. I want to integrate them in an economical way to produce great product.

Please share your thoughts, facts, experiences and more questions.

In great spirits,

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We use both but more copper. I don't know but it seems that I have noticed a difference. I know that there are a lot of other variables that affect flavor profiles. It seems though maintenance is an issue, it's something you have to live with. Heck, even Dave Pickerel from Maker's Mark told me that he's tried both and stayed with copper.

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If my memory serves me correctly, the folks from Christian Carl said that they prefer copper for the pot, head, column & plates but that they want stainless steel for the spirit pipe and the condenser. Their reasoning for the change to stainless in the spirit pipe and condenser is that the copper can leave precipitates of metal in the spirit, which may appear in finished product as sediment. Also, the copper in the condenser can create haziness. Nevertheless, I built my condenser entirely of copper (mostly because I can solder but not weld).

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I have been doing lots of research on the copper issue. My still is all stainless, coming from a brewing background just figured it would clean up better. After a few runs we found the sulfer compounds were coming through and started adding copper packing. It took quite a bit before we got the desired results. The fermentation also will change your sulfur compounds, with high gravity fermentations the yeast is stressed and will produce more undesirables. If you are hell bent on stainless and plan on doing whiskey I would make sure to incorporate copper somehow into your process on the hot side. Let me know if you want to talk further.

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Great feedback! keep it coming, I love stainless for all the reasons that are obvious, I also am a welder. For my stripping still, it will be all out of stainless. let's face it, a stripping still is to save the life of your high dollar copper finishing still. it will also double your output for much less money than buying another cash cow. I have seen some interesting alternatives. I like some more than others. when it comes to surface area, an average 600 liter still has around...900 square feet(very rough) in the pot sides, top and bottom. my question to the chemists-is there another way to remove sulfer from the final product? I have to think there is, that said it may not be economical. I have a way to match the surface area with a bolt in spool piece. it would be a little expensive, but not like building completely out of copper. plus it would be servicable by a knuckle draggin' monkey such as myself,lol. I can put around 750 square feet in this design. stainless steel is easier to maintain. it has not got the curb appeal most people expect from a high falutin' whisky producer,lol. good stuff...

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From a purely aesthetic standpoint, you could possibly do something on the lyne arm where the single tube can be flanged into a multi-tube segment, not unlike a shell and tube heat exchanger without the shell...where the tubes are all copper. The multiple tubes would lend much surface area for a comparable pass-through area. It would be like your idea of a spool piece in either the column or, perhaps as an artistic twist on an air-cooled pre-condenser in the lyne arm.

So, like, what you said...only different :)

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Chemistry-wise, you could run the spirit through a resin or zeolitic support loaded with copper or silver. Not sure it's allowed under the regs - at least without TTB approval. Nor do I know where you'd get the resin (food grade, at least) or how you'd regenerate it. Hmmm, Gusmer cellulo makes a cellulose filter media impregnated with Cu. 40cm sheets, but I cut them down for my 20cm plate & frame filter. Call them up (used to be the Wine Lab.) and ask about the SRM - sulfide reducing matrix. I've used them on troubled perry with nearly miraculous results. There's also a metal reducing matrix.

If you're building your still, you could also consider incorporating a few sieve plates, as opposed to bubble plates. Basically a flat tray with wire screen, or collander-like bottom. Fill it an inch or two deep with copper 'saddles'. I think the easiest way to make the saddles would be to chop up a bunch of 1/4" soft copper tubing, wash it and activate it. You'd want enough access to it to be able to open it up, and fish out the saddles in order to rejuvenate them.

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I have been doing lots of research on the copper issue. My still is all stainless, coming from a brewing background just figured it would clean up better. After a few runs we found the sulfer compounds were coming through and started adding copper packing. It took quite a bit before we got the desired results. The fermentation also will change your sulfur compounds, with high gravity fermentations the yeast is stressed and will produce more undesirables. If you are hell bent on stainless and plan on doing whiskey I would make sure to incorporate copper somehow into your process on the hot side. Let me know if you want to talk further.

Could you cut the pitch rate down? The lag phase will be longer but the stress would be reduced.

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  • 3 weeks later...

I have played around with pitching rates and it seems that the final gravity is much higher when less yeast is pitched. When we make beer the yeast will go through a nice growth phase and finish the sugars out, but with our rum washes it appears that the growth is less. I think temp. control might be the real key to subdued volatile production.

Could you cut the pitch rate down? The lag phase will be longer but the stress would be reduced.
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