I wouldn't worry much about evaporation since as I understand it, barrels typically lose between 0.5 - 1.5 percent of the current alcohol content annually depending on the tightness of the cask, the current ABV of the fill, and the conditions the cask is stored in. Assuming a 1 % average loss then if you start with a 46% fill, then after a year the ABV would be at 45.5%. This does argue that you should start with a higher proof charge rather than a normal commercial level bottling of 40%. Not sure how this will work for a much smaller cask but we have a pretty accurate hydrometer calibrated for alcohol content we'll use to track the changes in ABV as part of the "home warehousing" process.

There are a range of cooperages that sell new barrels on the internet but this is largely aimed at the wine industry instead of for aging spirits - not surprising since it's almost impossible to distill legally at home in the US. For wine applications they often recommend using a product like Barolkleen (www.homebrewit.com/aisle/1140) to strip out excess tannins before you use the barrel. I'm not convinced this is required or even done for aging bourbon (new casks) or subsequently for scotch whisky (refill bourbon casks) since the tannins are a huge component of the desired final product.

I'm still researching options and procedures but I'm now strongly leaning towards an initial use of a 1-gallon charred barrel, conditioning it for 6 months using a mid-range bourbon (not cheap but also not a bourbon that's already perfect for drinking) and then using it to age a gallon of the original US release of Springbank 10 yo from about 4-5 years ago. I made the mistake of buying a case of these without tasting it and it needs some help - it's drinkable but not transcendental as Springers so often are. The spirit character is fine but it was bottled too young IMO and has that estery green grassy character typical of younger malts.

We'll sample it as it ages to determine how long to leave it in the cask but the general rule here is that the smaller casks mature MUCH faster than larger casks due to the increased ratio of internal surface area (the contact zone) to the volume of spirit. We also own and have tasted samples of Bruichladdich stored in small (10 gallon?) "blood tubs" at their warehouses on Islay and this spirit is maturing MUCH faster than the fullsize barrels we also own at Bruichladdich as well as a couple of other distilleries. Some folks have already started bottling their Port Charlotte blood tubs at 4 yo but most folks are letting theirs mature for a couple of more years.

Of course, we'll need to archive incremental samples of both the bourbon conditioning as well as the spirit we fill the bourbon-conditioned casks with and then take comparison samples every few months so we can assess the entire process to determine when we rebottle it. I'm thinking we'll see detectable changes within a couple of months.

Surprised I haven't found much information on this topic yet... next best thing to owning a distillery IMO! The most promising cask I've found in the US so far is at www.redhillgeneralstore.com/A47524.htm but I'm going to continue researching my options before I pull the trigger and start my home warehousing project in a couple of weeks.

I'll post more as I move forward and will probably put up a section on my website to collect the procedures and provide photos sometime this summer.

slainte!

As a followup to your comments re: "bottle aging":

I also agree that many malts improve markedly once opened and when some headspace in the bottle is provided. The initial US release of the Springbank 10 yo 100 proof bottling is a good example of this. Last July we opened both the current US release and Euro release bottlings of the 10-100 (euro proof system is different and this one is actually 57% ABV) to do a head-to-head evaluation at a whisky tasting party.

No comparison! Even watered down to the same strength the Euro release was far better than the bottles they were simultaneously sending to the US. The US bottle is still open and about 1/2 full (the Euro bottling didn't last a month) and I tasted it during an online whisky tasting last week and it's remarkably better. However, when compared to the new Euro release 10-100 (the new black label lineup that includes the springer 10, 15 and 10-100 in Europe) the newly opened Euro release was still far better and even better than the last Euro release. This one is peatier than the last version but then again, springer bottlings vary significantly even within the same release sequence so no guarentees they will all be peatier.

I'm now thinking for the currently available US 10-100s (yes, I have a handful of these in the archives as well - D'oh!) that maybe I should open a bottle, pour off a 120 ml sample and then let it sit of the shelf a year before I expect to drink it...

Also, don't know anyone who has added oak chips to even age whisky faster or maybe even in the bottle but there's something that seems a little weird about this to me. Functionally it might work just as well but the esoteric, totally obsessive-compulsive approach to adding a few live casks to the drammery is much more appealing to me than going the oak chip route. Seems like "cheating" to me and I've never heard of the scottish distilleries doing this although I have heard of this being done with bourbon or corn whisky.

Never forget that perception IS reality.

slainte!