TOTM, 5/07: Doublers

[jeff]

This month let's expand on the distillation process and move from the still to the doubler. Sometimes called a "thumper", this device further refines the distillate and increases the proof of the whiskey before barreling. Discussion should include: How does one operate, the differences between a "thumper" and a "doubler", typical entry and exit proof, and other general comments by those familiar with the process.

Let's further refine our knowledge of the distillation process! (pun intended)

Sound off

[cowdery]

The traditional doubler is virtually the same as the spirit still in a two- or three-step all-pot-still process, in that the spirit is fully condensed before being reheated. A thumper takes the hot, uncondensed vapor from the column still and introduces it into the doubler below the liquid level, producing flash condensation and instant re-vaporization without added energy. The flash-condensing vapors make a loud thumping noise, hence the name.

The thumper is desirable primarily because it is more efficient, i.e., it uses less energy. Thumper-users say it works just as well, whereas users of traditional doublers claim the thumper is less effective at eliminating the bad high boilers.

Doubling (a misnomer, because it doesn't double anything) is unique to American whiskey making. All other spirits that are made in a column still use only a single distillation, since a column still is capable of achieving any proof in a single pass.

[jeff]

since a column still is capable of achieving any proof in a single pass.

If that's true, and I believe you are correct, what is the argument supporting the use of doublers?

[Gillman]

I think part of the answer is tradition, and tied into that is the size of column stills (many are quite old, e.g., Barton's dates back to the 1940's I believe, or one of them does). You only get a certain amount of ethanol purity with the columns that are traditional: they have so many plates and are so high, which produce therefore a purity quite under 100%. To get an enhanced purity, you need to redistill. In a normal traditional set-up, you have a column still (beer stripper) and rectification column, and sometimes an extractive step between, which involves use of yet another column. You could put a reflux extension on a column still, which would increase purity and perhaps avoid the need to distill twice, but this isn't traditional for bourbon manufacture. The only question is, is your abv high enough in the first run to ensure the required purity? And the required purity ensures elimination of the most objectionable congeners. This is my understanding anyway.

Gary

[nor02lei]

As I did understand from the column still thread, head and tail are only partly removed in the first distillation. Still in the second distillation many/must distilleries only save the middle cut and others barrels it all. Could someone explain this theory behind this somehow?

Leif

[cowdery]

The best explanation I can offer is that when American whiskey distillers have tried to do without doubling, the whiskey didn't taste right, didn't taste good, so they went back to doubling. In the 60s-70s, when almost everybody was treating bourbon like a commodity and trying to make it as cheaply as possible, several distilleries stopped doubling and also took all of the copper out of their stills (this information comes from Vendome's Tom Sherman). The result just was not satisfactory.

Distillers say the doubler "polishes" the spirit. A column still set on 11 (Spinal Tap reference) produces a neutral spirit, everything stripped out. Apparently, to distill at a lower proof for whiskey, take out the bad stuff and leave the good, you need to follow column distillation with pot distillation, which is what a doubler is, a pot still.

Pot still devotees say the pot still provides finer control. That seems counter-intuitive, but perhaps that is the answer.

I've talked to some of the most knowledgable people in the industry about this and they can't give a precise explanation, except to say that you can't make a good tasting whiskey without doubling. They know because they tried and it didn't work.

As for Leif's question, part of the problem is that talk about heads and tails and middle cuts is really pot still terminology. It doesn't exactly apply to the American system. What is the case is that some unwanted congeners boil at temperatures above the boiling point of ethanol (high boilers) and some boil at temperatures below it (low boilers) and it takes a variety of strategies to get all of them while preserving the congeners that contribute positively to the taste, which in some cases are the same as the bad congeners, just in smaller concentrations. Each distillery does this a little differently and, of course, each believes that the way they do it is the best.

[Gillman]

I agree with the nub of this since e.g., WR's pot still element is distiiled three times, to a proof higher than many other distillers distill out at, yet the spirit has residual secondary constituents of a type to make a very robust white dog. I think Chris Morris has said that Versaille's triple pot distilling, even resulting in a higher final proof than column stilling + doubling, will result in a heavier spirit. So it is not apparently just a question of final ABV, there are intangibles and apparently they best manifest under the system of column stilling plus doubling.

Gary

[nor02lei]

One thing has struck me in the 2 still threads as not being discussed. It is the significance of copper in the stills. Correct me if I am wrong but I do see a slight difference between American straight and other quality sprits. Stills made of entire copper are as far as I know mere or less a rule in distilling of rare sprits. When it comes to bourbon it is also said that copper is of big importance. However many/most American distilleries have their stills in a mixture of copper and steel. The newest distillery Bernheim had their stills entirely in steel from the beginning.
I have also read on this forum that not one but several posters have thought that the WR 4 grains had a bad taste of copper/metal, which is a statement I have never heard of any other spirit. Personally I’ve only had one half pour of the first batch at the Gait house in Louisville and I can’t recall any “copper” taste but it did taste very young and immature though.
Visiting the WR distillery Chris Morris offered me a barrel sample in the dump room from a copper distilled WR barrel of about 117 proof. To me it tasted excellent with no “side” tastes and actually better than the normal WR.
When I did visit the HH distillery in Louisville I did ask Charles Downs if they had noticed any difference/impairments in the spirit after moving to the new distillery in Louisville. A bit surprisingly he answered that it was just the case. However too compensate this they had partly rebuilt the stills and put some copper parts into them. After that according to Charles the taste was so close to the DSP 31 that they were fully satisfied.
The van Winkle 10 and 12 years are, as I understand made from the 100% steel stills at the Bernheim distillery and many/most members here including myself seem to like them.
All these facts make me a bit confused and I am glad for any comments.

Leif

[cowdery]

I would be very surprised if new Bernheim was ever 100 percent stainless, but I know Heaven Hill made quite a few changes when they took over, including the addition of a lot more copper.

I was told by Tom Sherman at Vendome that the all-stainless stills were made in the 70s and 80s, when everybody was trying to cut costs. Without going into detail, it was a big race to the bottom. However, most producers came to find the product of these stills unsatisfactory, at least for straight whiskey, and they began to put copper back in. That is why I find it extremely unlikely that new Bernheim, built in 1991-92, would ever have been all-stainless.

De-misters are a good example of how column stills can expose the spirit to a lot of copper content. Consisting of many layers of copper mesh, they are placed at the very top of the still.

Copper contact is salutary because it reacts with sulfides and keeps them in the still and out of the whiskey.

I like to say that, in America, all of the copper is inside the stills, where the whiskey is, and not outside where the tourists are.