How can Stagg reach 147?

[rccoulter]

I know that bourbon can't enter the barrel at greater than 120 proof. And I understand that evaporation accounts for some higher proof bottlings like Bookers. But an increase of 14% abv?

--Can anyone explain to me how this works? And why we don't see more bottlings above 130?

[TNbourbon]

Actually, the law states bourbon can be barreled up to 125 proof, not 120 -- a minor difference, but perhaps signicant on the other end. Additionally, Stagg is a 15yo, meaning that when the barrel is unsealed, already at least a third, probably somewhat more, of the contents have evaporated (Elmer T. Lee says 7-8 percent the first year, then 3 percent thereafter -- if so, after 15 years, less than half would be left). Presumably, most of what evaporates is water, thus leaving the higher alcohol content. All in all, 147 proof doesn't seem that out of line to me -- an 18 percent or so increase in abv [(147-125)/125=17.6] from a 33-40-percent (at least) decrease in total volume.

[cowdery]

It's entirely a function of evaporation and not that unusual. Some of the 1992 vintage of Evan Williams Single Barrel came out of the barrel at 145 proof, and that's just a 9-year-old.

The part I have trouble wrapping my head around is that distillation is based on the fact that alcohol vaporizes at a lower temperature than water, so why is it that it's water that is mostly lost in barrel evaporation and not alcohol?

[SteveZZZ]

Just an uneducated guess, but maybe the alcohol that evaporates can't get through the wood, while the water can. It's the only explaination I can think of at the moment, but that doesn't mean it's correct

Steve

[doubleblank]

Alcohol does have a lower boiling point than water and the vapor space inside the barrel will have more alcohol that water vapor. But alcohol is a larger molecule than water and it may not "wick" through the wood as fast as water might. The oak barrel might actually be trapping the alcohol inside the barrel while letting the water migrate to the exterior surface and evaporate (relatively speaking).

Randy B.

[voigtman]

Well, it seems that one "Tim Dellinger" posted a very nice answer to this matter of how whiske(e)y can increase in proof on the M****-L newslist (sorry for the reference to those infidels), back on March 24th, 2003. (I found it and printed it out, to be sure I remembered it right.) He can speak for himself, VERY capably, and I will not put words in his mouth. But, in brief, final proof depends on lots of variables: barrel specifics, entry proof, integrated temperature history of the barrel over the years, and other variables as well, but the big difference between ethanol (aka "alcohol") and water is that air always has a relatively high humidity, whereas the ethanol partial pressure is fairly small (though I do not doubt for a minute that the warehouses smell just GREAT). It comes down to the ratio of ethanol to water, integrated over the years, the temperature, integrated over the years, and the humidity, integrated over the years. Bottom line: no human being has anywhere NEAR the data to predict which barrel will wind up with a proof above entry proof. That is the "magic" of the process and I hope it stays that way!

OK, I know Pappy Van Winkle had that famous sign about "No Chemists Allowed" in his distillery, and I think he was right, despite being a chemistry professor, but we have our uses: if we can help with these types of issues, great, but I hope the whisskey making process stays firmly in the hands of the master distillers and sc*** the "analyze it to death" approach! Just my opinion, of course.

Cheers, Ed

Ps. Whisky magazine, issue 37, arrived last Wednesday and Chuck Cowdery has an article on pages 46 and 47. Very nice work! And our own "Paradox" was shown, with a SMALL portion of his astounding bourbon collection, on p. 47. Nice info on Bobby Cox Jr., the Lipmans, and Omar, also. Excellent work!

[doubleblank]

My good friend Greg, a Physical Chemist who used to design WMD for us but now runs a chain of Hallmark stores (talk about a change of careers), confirmed that the molecular size difference makes the biggest differest in the change in alchol content. He used to run a lab for the DOD, and he believes, in laymans terms, its easier for water molecules to escape the "confines" of a wood barrel than water.

Randy B.

[Gillman]

But why then does proof generally decline in the barrel in Scotland?

Gary

[TNbourbon]

My immediate, off-the-cuff response (guess?) re Scotch is that it spends its barrel years in a more uniform, lower-temperature climate.

[gr8erdane]

And all along I just thought it was the Bourbon Fairies waving their magic wands....

[voigtman]

The humidity in Scotland is very significant (as in usually very high), from what I've read, so water loss is lessened relative to what it would be in a dry environment. But the ethanol loss is independent of humidity. In Scotland, the ethanol molecules are more readily lost than the smaller water molecules because the environment around the barrels/casks is humid and has only very low concentrations of ethanol (otherwise the folks in those facilities would be having a hard time staying on task!). In Kentucky, the generally dryer climate means that water molecules are preferentially lost. Both ethanol and water molecules are being lost though the wood to the air around the barrels, but the water loss can exceed the ethanol loss in a dry environment. On the other hand, the water loss can also be less than the ethanol loss: it is all complicated by differences in what might appear to be identical barrels, the detailed history of where the barrels are spending their time aging (way up near the roof, close to the floor, deep inside the facility, etc.), and the detailed temperature and humidity history of each barrel. I would look at it as each barrel being a little "universe" unto itself, so I would not be surprised if two apparently identical barrels, filled on the same day with the same new make spirit, should end up with significantly different proofs. Even if one ended up above entry proof and the other below it. Cheers, Ed

[tdelling]

>The part I have trouble wrapping my head around is that distillation is based on

>the fact that alcohol vaporizes at a lower temperature than water, so why is it

>that it's water that is mostly lost in barrel evaporation and not alcohol?

This is what I call "The Apparent Contradiction", and you've done a good job

putting into words. (Perhaps you should be a writer ).

I've dug through the whisk(e)y literature a fair bit looking for a

possible explaination, and I haven't found one. Yet. But if you sit

and think for a while, though, you eventually conclude that the answer

must be that wood somehow interacts with water different than it interacts

with ethanol. The way I see it, there are two possible causes that

might contribute:

1) Ethanol is less soluble in wood than water is. If the ethanol has a

harder time getting into the wood, then less of it will make it out the

other side.

2) Wood is more "permeable" to water than to ethanol. Perhaps there are

barrier-layers of some sort (cell walls? growth rings?) that are difficult

for ethanol to cross, thus reducing permeability.

I haven't seen any published data concerning either situation.

As an aside, I will mention that a tree trunk is designed with water

transport in mind. It has to pull water out of the ground and

(through capillary action) bring it up to the leaves and branches.

It has been pointed out to me that most of the trunk does not in fact

participate in this endeavor, but rather a thin green layer right below

the bark is where all the water flows.

Most of the wood chemistry that I've looked at concerns wood degradation

in the presence of ethanol and water. I might find some answers if I

start looking in some of the more traditional wood chemistry overview

books.

Tim Dellinger

[tdelling]

>Well, it seems that one "Tim Dellinger" posted a very nice answer to this matter

>of how whiske(e)y can increase in proof on the M****-L newslist (sorry for the

>reference to those infidels), back on March 24th, 2003.

I'm guilty, as charged.

What I was really addressing in that post was the quandry that for some

reason in Scotland, whisk(e)y decreases in proof over time, whereas in

America, the opposite happens: proof goes up. The answer, of course,

is humidity.

>...He can speak for himself, VERY capably...

That's rather flattering, but in actuality, I'm just a Fool with a passion

for science of all sorts, a love of whiskies, and an argumentative streak

that was honed by living with pre-law students who are now trial lawyers.

I'm rather happy to see that there are now others here on Straightbourbon

who also share my interest in technical matters concerning bourbon. I

really enjoy the other contributors here.

>OK, I know Pappy Van Winkle had that famous sign about "No Chemists Allowed"

>in his distillery, and I think he was right...

>...

>...I hope the whisskey making process stays firmly in the hands of the master

>distillers...

Two points:

(1) Chemists might try to analyse things things to death, but in the end,

every last one of them has a whole handfull of tricks that are just plain

"black magic". Things that "just plain work, we're not quite sure why,

but anything you do, don't change the recipe!" We have a healthy respect

for effectiveness. It is true that we like to tinker, and we often

can't stop ourselves from attempting to optimize everything we come

across...

(2) I think that in the end, it turned out that the real enemy was not

the chemists, but rather the accountants.

>...despite being a chemistry professor...

Be careful saying things like that! The first time I said "gas chromatography"

around here, I almost got shot at!

Tim Dellinger

[TNbourbon]

Gas chromatography? -- I think that's what the doctors used to look at my colon during a decade-long bout with ulcerative colitis They finally just removed the thing, making me a real-life 'gutless wonder'.

[cowdery]

To muddy the water a little big, consider Wild Turkey Rare Breed, which is bottled at barrel proof. Wild Turkey, we know, goes into the barrel at about 110 proof. So what is Rare Breed's barrel proof? 108.

[Dave_in_Canada]

Chuck, this past summer in a discussion with Eddie Russell, he stated that the proof lowers in the barrel (at least the specific barrels he was pointing to). We were in a particular warehouse, and I may have taken his words "out of context". I have often thought he was mistaken - I did not want to press the issue - but I'm now surprised to learn that if one does the research, proof can either increase or decrease with barrel storage/aging.

[gr8erdane]

Could there be a phenomenon that the proof goes down to a certain point in aging and then goes up again? Might it be a seasonal thing as we are told that in the warmer months there is more bourbon soaked into the wood and either absorbing or leaving the alcohol? And could there be a point where ethanol is produced by the oak barrel adding to the proof? Curiouser and curiouser.

[Marvin]

Chuck,

That question has been raised ever since I have been reading books, asking master distillers and any one else that would listen to me and no one has ever answered my questions satisfactorily. So, a few months ago, I did an experiment. I made two little wooden boxes out of white oak. I drilled a little hole in the middle of each, so they would leak. I filled one with water and the other with alcohol and then sealed them. After a few days, the one with water in it stopped leaking but the other one did not. So here is the way I look at it, water soaks into the wood and expands it stopping all leakage, but alcohol will not stop a leak. You need the water to contain the alcohol. It is all the water that goes into a barrel; for example- if you had a 50/50 mixture and 10% of the water went into the barrel then you would have a 60% alcohol content, which is a 10% increase. I have tried this experiment several times and each time the results were the same. I think this might be the answer to your question, at least until somebody can prove me wrong!!

Cheers,

Marvin

[bourbonv]

Chuck,

Warehouse location. The higher the hotter it gets and the more proof is gained. The lower and more towards the center conditions get more like Scotland and proof is not raised and may be lowered.

Mike Veach

[tommy]

This EPA document discusses evaporation a bit. Click on the "Emissions" bookmark.

EPA on whiskey

I hope this works--never tried to do a link before!

[jimbo]

It's entirely a function of evaporation and not that unusual. Some of the 1992 vintage of Evan Williams Single Barrel came out of the barrel at 145 proof, and that's just a 9-year-old.

The part I have trouble wrapping my head around is that distillation is based on the fact that alcohol vaporizes at a lower temperature than water, so why is it that it's water that is mostly lost in barrel evaporation and not alcohol?

Well, maybe not. Alcohol is more volatile than water under all conditions. More alcohol than water will always evaporate. For example, if the humidity was 100%, NO water would evaporate but alcohol would evaporate unhindered. So the percent alcohol in the barrel would decrease over time. If the humidity was 0%, both water and alcohol would evaporate but since alcohol is more volatile than water, more alcohol would evaporate. So the percent alcohol in the barrel would decrease over time. There is just no combination of time, temperature or humidity that would cause more water than alcohol to evaporate.

But, migration of liquid in the barrel through microscopic pores in the wood could lead to an increase in the percent alcohol in the barrel over time. These pores are not big enough to be a "leak", but big enough to allow molecules of liquid to travel from inside the barrel to the outside, somewhat like liquid travels through a wick. Since water is a much smaller molecule than alcohol, water would migrate out of the barrel at a higher rate than alcohol and the percent alcohol in the barrel would increase over time.

So, if whisky in Scotland decreases in percent alcohol over time in the barrel and whiskey in Kentucky increases in percent alcohol over time in the barrel there must be some factors present in the respective environments that causes the loss of liquid from the barrel to shift between evaporation and migration. I suppose conditions from place to place in a warehouse could also result in shifts between evaporation and migration which could lead to some barrels increasing in percent alcohol and some barrels decreasing in percent alcohol.

Anyway, it would be interesting to see some actual measurements of percent alcohol in the barrel over time from several locations in a warehouse.

Regards, jimbo

[jimbo]

Just one additional thought. If there was a place in a warehouse where the atmosphere was saturated with alcohol vapor (100% alcohol humidity) then NO alcohol would evaporate, but water would continue to evaporate. So the percent alcohol in the barrel would increase over time. It seems unlikely that such a situation could exist, but who knows? I guess distillers could even build special rooms where there was no air circulation and alcohol vapor could accumulate. The problem with such a scenario is that if the room or location allowed alcohol vapor to accumulate to saturation, then water vapor would also accumulate to saturation and all evaporation would stop.

Regards, jimbo

[tdelling]

> Since water is a much smaller molecule than alcohol, water would migrate out

> of the barrel at a higher rate than alcohol and the percent alcohol in the

> barrel would increase over time.

You've grossly oversimplified things here. "Size" isn't really the answer here.

Yoahizawa et. at (J Agric Chem Soc Jpn 55: 1063-8, 1981) studied "Subastances

Evaporated Through Barrel of Whisky", and found the following losses over time:

acetaldehyde 32%

ethanol 12.7 %

acetic acid 1.0%

These molecules are very close in size, but very different in barrel

permeability!

Tim Dellinger

[tdelling]

> Anyway, it would be interesting to see some actual measurements of percent

> alcohol in the barrel over time from several locations in a warehouse.

The only published numbers I'm aware of for American whiskey are in

GH Reazin, Am J of Enology and Viticulture 32: 283-9 (1981)

There's probably more data out there, I just haven't found it yet.

Tim Dellinger

[jimbo]

You've grossly oversimplified things here. "Size" isn't really the answer here.

Maybe, but the point I was trying to make is that loss of liquid from a barrel is more complicated than just evaporation. And that a "migration" mechanism through the wood could explain how the percent alcohol in a barrel increases over time.

Regards, jimbo