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by Lew Bryson
Gleaming copper stills dominate our images of Scotch whisky-making. Three copper pot stills are at the smooth heart of Irish whiskey. And bourbon lovers may know of the copper pot stills at Woodford Reserve, or at least of the tales of copper scrap tossed into the tall steel column stills at other distilleries. If the best examples of humanity have hearts of gold, surely whisky has a burnished heart of copper.
It’s been that way for a long time, centuries. But while the first stage of whisky-making, brewing the beer, has largely gone over to the longer wear and markedly lower maintenance of stainless steel vessels, distilling still clings to copper. Is it tradition? No, not really, nor is it because of any desire to get full use out of stills already in place, or because of fears of changing the spirit by replacing the still: copper stills have to be replaced over time anyway.
It’s because copper turned out to have an absolutely essential role in distilling whisky. What the full extent of that role is remains to be determined. "Of all the bits and pieces we know about distilling," said Glenmorangie’s global brand ambassador Dr. Bill Lumsden, "copper is probably one of the ones we know the least about. It’s one of these subjects that will be researched for the next fifty or one hundred years, and we’ll still not fully understand it."
Cooperative Copper
There were always plenty of good reasons to use copper in stills. It was available, and relatively cheap. Copper was malleable to a fault, shaping easily to the beautiful, almost seductive curves of a pot still. Also, copper’s excellent heat transfer properties worked well with the externally-fired stills of the early days.
One of the best reasons to use copper in earlier times was the lack of a good alternative. "You have to think about that," explains Brown-Forman distiller Chris Morris. "Before copper, the only metals that were available were brittle metals like iron. You couldn’t use iron because that makes the spirit black. Tin and other metals that were also too brittle and broke down too easily. More malleable metals like bronze were too damned expensive. Copper was something you could afford to make a still out of 100%, and it was malleable."
All along though, while copper was cooperatively, cheaply chugging along, it was performing other duties distillers didn’t even know about. It wasn’t until things changed that distillers were presented with the mystery of just what copper was doing.
First they had to figure out that it was copper that was making things right. Stainless steel was both the key and the culprit.
Chris Morris led into the story like this. "The big age of discovery [in whiskey] is after Prohibition," he explained. "People were opening up distilleries, borrowing money, getting capital and investors, and they started asking: how can we make things last longer, be bigger, be better, all that kind of stuff. Well, here’s this stainless steel."
Morris’s colleague, Brown-Forman master distiller Lincoln Henderson, picked up the thread. "They probably went to the stainless steel," he said, "not necessarily using copper in the system, and found out there was something wrong. I think that’s probably what encouraged the research."
" Something wrong" is putting it mildly. Ask Jim Murray, author of Jim Murray’s Whiskey Bible, what whisky would taste like without copper in the distilling. "That’s an easy one," he said. "As often as not, diabolical. The less copper you get, the less sweetness and honey tends to be around. Often you pick up a cabbage water aroma-at its worst, it takes me back to the old days when my mum used to boil hankies. Copper adds a sparkle to the nose; stainless steel stills offer something often flat and lifeless."
Murray then brought up a whiskey that was downright notorious for its display of the necessity of copper: Lammerlaw. "The best example of a whisky being made in a copper-free still was at the old Wilson Distillery in New Zealand," he said. "I was unlucky enough to taste the spirit from that original still and it was absolutely dire. It had no shape, character, or life. It is was flat and unpleasant in that uniquely un-copperish way. If you drank it, then you had to be desperate for alcohol. Then changes were made to the still, with copper being added to the system. The effect was extraordinary: overnight it became a much richer spirit. A little copper in the right places can go a long, long way."
Capturing Brimstone
Just what is it that copper does, then? It turns out that the "cabbage water" smell is sulfur. Bill Lumsden described copper-less whisky in terms similar to Murray’s. "It would be very pungently sulfury, meaty, almost a cabbagey smell," he said, and then added, somewhat unnecessarily, "not really what you would want."
Where’s sulfur coming from in whisky? The sulfur is in the grains themselves, pulled out of the ground. Irish Distillers’ master blender Barry Walsh said that in days past, there was another, nastier source of sulfur. "The presence of copper during a distillation of whiskey or brandy was rather more important in the old days," he said, "as the cereal wash or grape must tended to become infected by bacteria before the distillation. The bacterial infection resulted in pretty noxious sulfur compounds being generated in the wash/must, rather more than would be the case by the yeast alone."
As the grain is mashed and the wash or beer is distilled, the sulfur winds up in the spirit. That’s when the copper starts its work. "The copper attaches to the sulfur to form copper sulfate," said Lincoln Henderson, "and it’s black."
The black stuff-mainly copper sulfate and oils and fats from the grain, with some other compounds-collects on the copper, and is visible on the spout where the wash still pours the spirit into the spirit safe. At Woodford Reserve it is particularly heavy. "Another part of it, the greasy and thick part," said Morris, "is unique to Woodford Reserve: those pot stills are unique in that they are handling a beer mash, as opposed to a wash, as over in Scotland or Ireland. So we get a lot of corn oil. Corn is an oily grain."
It is a crusty, greasy mass, and it reeks of copper, the kind of smell that grabs your nose by the ganglia and swings around like Tarzan in there. "The grunge," said Chris Morris. "We call it the grunge. Don’t touch it, you’ll be washing the smell off your hands for three days. It starts forming at the top of the gooseneck, in the lyne arm, all the way through that condensation structure. You just see the tail end of it coming into the spirit safe."
Barry Walsh, a seemingly inexhaustible source of interesting bits and pieces, pointed out that the copper picking up fats and oils in the Woodford Reserve spirit still worked the other way in copper mining. "As an aside," he mentioned, "the flotation method in copper mining is when fatty materials are pumped into a free copper-containing solution; the resulting copper/fatty compounds rise to the surface as a sort of green sludge."
What else is in the grunge? "In fermented beverages you get-well, chemically, it’s a polymer," said Morris. "It’s called ethyl carbonate, a compound that comes from the grain fermentation. It doesn’t really have any flavor, it’s just something we don’t want. When you hear someone talk about EC levels, that’s what they’re talking about. The copper’s cleaning that out.
" The grunge is removed when we run a caustic wash through the still," Morris continued. "Any caustic wash through a copper still will include levels of zinc and copper that are not acceptable to our waste water processors. The caustic wash is directed to the stillage tank and mixed with the spent mash and lees [used yeast] which are then sold to farmers for livestock feed. The addition of the small amounts of zinc and copper in the stillage is a benefit to the dairy farmer, who would add such supplements to the feed anyhow." Quite an elegant solution.
Copper Chopper
Copper definitely needs to be in the distilling process, and building your still out of copper is one way to put it there. But Bill Lumsden feels the most important place for the copper is where it will do the most good; where the hot vapors are condensing.
" Compare whisky made in a distillery where they have what you call shell and tube condensers," said Lumsden, "where the neck of the still goes over into the lyne arm into this large copper column, inside which there are up to 250 narrow copper tubes. We pump cold water into these tubes, so the vapors condense out and run down to be collected. Compare that to the more traditional method of condensing, which we call worm tubs-this is basically a large tank or vat of cold water, into which the neck of the still coils round in an ever-decreasing diameter of copper pipe, just like a worm coil, but thin-sided.
" The surface area of copper available to the vapors in a worm tub," he continued, "is a fraction of that you have in a condenser. The whisky made in a distillery with worm tubs is typically much more meaty and sulfury in character. The only distillery I know of which currently utilizes both types is Linkwood distillery. I was posted there as a trainee manager in my distiller’s days, and I did a few experiments on my own, looking at the two different spirits. I could pick out the difference, nosing and tasting blind. There was such a distinct difference. That’s a quite dramatic illustration of how having a greater surface area of copper can really make a great impact on your spirit."
We haven’t talked much about column stills, but copper’s just as important there. "The column still was introduced to Kentucky in a big way in the 1890s," said Morris. "Those column stills were by and large, believe it or not, wooden, with copper fittings. They were very tall barrels." When stainless steel came into use post-Repeal, copper’s chemical role suddenly became apparent, and intensive research at Seagram’s determined the whys and wherefores.
But you still see a lot of stainless steel column stills. How come? "We do have 100% copper column stills at Jack Daniel’s," said Morris. But we have hybrid stills at the Old Forester distillery; they’re stainless steel and copper. The exterior shell of the column, with the infrastructure inside, the boil plates, etc., are copper."
" We also throw additional copper in at the top," added Henderson. "It’s a very scientific thing, we cut copper tubing up and throw it in there. It lasts till the copper simply disintegrates."
That’s an almost sentimental thing: copper stills slowly disintegrate as the copper is used up by the chemical processes. The still gives itself to the whisky. "The typical lifespan of a still varies," explained Lumsden, "depending on what part of the still you’re talking about. In the wash still, it’s the neck and the lyne arm that tend to get attacked first. Typically they last about ten years. Whereas in the spirit still, it’s the main body of the still that goes first, in eight to ten years."
How fast depends on the distillation schedule. Lincoln Henderson said that the cut-up copper tubing at Brown-Forman lasts about three years. "When we pull it out it’s the thickness-or the thinness, whichever way you want to look at it-of paper. It will crumble in your hand. That shows the catalytic reaction in the still is just incredible."
Or as Jim Murray put it, "Copper is self-sacrificial: every time a copper pot still boils away it is giving part of its life to the whisky. The same can’t be said for stainless steel, which is mean and goes on forever."
While this sentimental mood is on...Barry Walsh put his finger squarely on one last benefit of copper. "The modern distillers could probably get away with just a small presence of copper," he said. "But old habits die hard; all those old roundy, shiny, coppery pot stills are things of beauty and long tradition! An Irish or Scotch malt distillery would be a barren place without them." As like cut out their copper hearts.
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