The many sought-after bourbon in the world, Pappy van Winkle 23-year-old, begins life together 53 gallons that new-make whiskey at 114 proof.

What's left in the barrel ~ 23 years is a only 14 gallons the bourbon at roughly 135-140 proof. What renders it right into the bottle is also less.

So I determined to run the numbers on just how much Pappy valve Winkle is left in the barrel yearly after evaporation (aka the "angel's share").

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According to Harlen Wheately, master Distiller in ~ Buffalo Trace, the angel's share is 10 percent for the very first year (because whiskey is soaking up into the wood of barrel and evaporating), climate 4 percent because that the next 8 years after that, then roughly 3 percent every year ~ that.

(They save the future Pappy in barrels in the parts of the warehouse through the least evaporation as they recognize they want it to period for a very long time.)

According come those calculations, there room 22.4 gallons left in the barrel, yet this assumes that the alcohol percent stays the exact same as the started.

The actual last proof is around 140 (70% ABV), so the 14 gallons the Wheately reports are identical to around 17.2 gallons at the initial proof the 114 (57% ABV). That's a lot of closer come the calculation number.

Wheately filled me in top top some other practical components for the math discrepancy.

“We have actually done a lot of proprietary work to identify the genuine proof autumn while the barrels room aging so i wouldn’t desire to expose all our info....

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(but)

While handling such tiny batches you obtain quite a little of loss during the bottling procedure during the filtration process.

Also, throughout the course of 23 years there often tends to be other factors such together leaks that rise the loss and also are daunting to placed numbers to. A typical/perfect 23 year old barrel that wheated bourbon need to yield about 14 alcohol gallons with around a 1-2 gallon loss throughout bottling which it s okay it down to 12-13 wine gallons recovered.”

So when you're paying for a party of Pappy van Winkle 23 even at non-surge pricing, you're not just paying because that the raw products used to make and also the time spent to period what's in the bottle, you're also paying because that the life materials and also aging of 39 gallons of bourbon the evaporated prior to it got to the bottling facility, and a complete of almost 80% that the initial juice the didn't do it right into the bottle.