Glass Maturation Pro Tip: Never Fill your Jars

[nzbourbonguy]

After 6 years of ranging experiments across different spirits, proofs, wood varieties, heat treatments, and other factors, I've identified a unique factor that holds more influence than most give credit: Headspace

Over the past few weeks, I've been assessing all of the glass jars I filled over the years to create a funky blend. All of the jars that I filled to capacity still have a bright new-make bite that doesn't exist in any of the jars filled below 2/3rds full or any barrel aged product.

There isnt much different between 1/4 to 1/2 full, but saw a bit more complexity for any of the 1/2 to 2/3 full jars. The 3/4 full jars were better than any full jar, but not as flavorful as the others in comparison.

This behavior was seen across bourbon, single malt, apple or grape brandy, and rhum

[Thatguy1307]

Interesting. So the amount of air in the glass made that noticeable of a difference? I wonder if sloshing the jars around to introduce more air into the distillate would make a difference.

[LWTCS]

Pour your jar into a pot from a distance.
Then pour it back into the jar.

[SW_Shiner]

I crack my jars and swirl every now and then to let new oxygen in.

[nzbourbonguy]

It really does make a difference.

All of these are great practices.

Also, the air gas mixture reaches equilibrium every 6 months, so if you decant the spirit into another vessel and back twice a year, it can ensure a constant state of micro oxidation in sealed vessels.

[MooseMan]

Great observation.

I go with shoulder filled glass and try to give them a hard swirl and a sniff as often as possible.

I have noticed also, that the ones I leave in my conservatory, which gets hot in the day and cold at night, smooth out the fastest.

[Deplorable]

Pour your jar into a pot from a distance.
Then pour it back into the jar.

+1
I usually do this a few times over a 12 month aging period. my batches are usually 1.5 gallons of barrel proof spread across two gallon jugs. Pouring them into a pot, and back into the glass jugs, blends the 2 jugs in the event there is any variation in the oak sticks they are sitting on, and introduces a lot of micro bubbles to help oxidize the whiskey.

[PalCabral]

Very interesting and thanks for sharing your findings. I've been trying to keep headspace in my jars but I know I have faltered. Will have a look at it this weekend and maybe the reshuffle a bit? I aerate the jars with an aquarium pump and a diffusion stone, or whatever, about once a month, and I do re-distribute the contents in jars at the 6 month intervall. If it make a difference I don't know but I like to think it does.

[nzbourbonguy]

Very interesting and thanks for sharing your findings. I've been trying to keep headspace in my jars but I know I have faltered. Will have a look at it this weekend and maybe the reshuffle a bit? I aerate the jars with an aquarium pump and a diffusion stone, or whatever, about once a month, and I do re-distribute the contents in jars at the 6 month intervall. If it make a difference I don't know but I like to think it does.

More than you realize. The redistribution and aeration both help promote oxidation, especially in the timeframe mentioned. Its ideal for maximizing possible air-gas exchange with sealed containers.

[PalCabral]

Very interesting and thanks for sharing your findings. I've been trying to keep headspace in my jars but I know I have faltered. Will have a look at it this weekend and maybe the reshuffle a bit? I aerate the jars with an aquarium pump and a diffusion stone, or whatever, about once a month, and I do re-distribute the contents in jars at the 6 month intervall. If it make a difference I don't know but I like to think it does.

More than you realize. The redistribution and aeration both help promote oxidation, especially in the timeframe mentioned. Its ideal for maximizing possible air-gas exchange with sealed containers.

Curious if the ABV may have something to do with it. At what ABV are you oaking your whiskies and rums, nzbourbonguy?

[nzbourbonguy]

The oxidative effects were independent of abv of the distillate.

The lowest would be 48% and highest was 72% amongst the various experiments. There are clear flavor differences from the proof that the spirit rests at. Ive even done a slow proofed grape brandy edv that started at 70.2% and worked down to 58% over the span of 4 years.

My preferences are:
53.5%-65% for whiskey
58%-70% for Brandy (most often still strength edv)
57%-68% for R(h)um (lower proof for higher ester content)
48%-52% for Tequila/Mezcal (or other agave spirits)