Wood- and Barrel-Aging Part 2: Small Barrel Handling
A quick primer Barrels come in a variety of sizes, from homebrewer-sized 5, 8 and 10 gallons, to commercial 59 gallon wine and whiskey barrels and beyond. Keep in mind that wood makes a great home for bacteria and yeast, so sanitation becomes a concern with the lower alcohol content of beer. Used wine barrels seem to create an ideal environment for Brettanomyces, which could be considered a plus for certain styles of beer, but definitely the author of off tones for others.
Why use a small barrel? Capability (or not) of brewing 60+ gallons. Once filled, how are you going to move it? (Hint: you re not. A typical, empty 59 gallon wine barrel weighs roughly 110 pounds. Fill it with beer, and it jumps to about 582 pounds!) Storage space. Variety! Ability to have several barrels going at once.
Why NOT use a small barrel? Staves tend to be thinner in smaller barrels. This leads to more rapid evaporation and oxygen ingress (greater chance of oxidation, which could be good or bad, but also increases the chances of acetic acid buildup) There is also a higher surface-to-volume ratio, so extraction of wood and spirit character will occur more rapidly.
Acquisition If you can, purchase a barrel locally. This will give you the opportunity to inspect it personally without having to possibly send it back to the provider, or be stuck with an unsuitable barrel. Small and large barrels can be purchased online from a variety of sources. Some local distillers even sell small barrels to homebrewers or homebrew shops. Larger barrels require a bit more effort. The more recently a barrel has been emptied, the better. It will more likely still by hydrated and watertight and free of unwanted bacteria.
Inspection If you can, inspect the inside with a flashlight. Lees or liquor are acceptable, mold is not. Check the outside, including the bottom. Scuffs and scrapes are OK; gaps, cracks and holes are not. Sniff the bunghole. Aromas of the previous resident (wine, spirits), or toasty and oaky notes are fine. Dank, moldy, vinegary, acetone (nail polish) or otherwise unpleasant smells are no good.
Preparation When you acquire a new barrel, you should have a beer ready to fill it, or at least be prepared to fill within a couple days. Check for leaks. Either fill completely with water, or put 1-2 gallons of water in and roll it to check for the appearance of damp spots on the exterior.
Preparation (cont.) Rinse to flush out any loose bits of char or other particles, as well as lessen the impact of the wine or spirit character, if desired. Do nothing and just fill it with beer can be risky if you THEN find out that your barrel leaks like a sieve. Try to keep it filled! If empty, it s more likely to allow mold growth or just to fall apart. If you can t fill it soon (within a week or two), then you should fill it with a storage solution to prevent microbial growth (see Storage section).
Usage For a freshly-dumped whiskey barrel, it s advisable to first fill it with a strong, dark beer (imperial stout or barleywine, for example), something that can stand up to and complement the spirit character. Sampling Temperature and humidity. Warmer temps will age faster. The 60/60 rule: 60 degrees and 60% humidity is ideal. When the barrel is full of beer and with a bung in the bunghole to prevent extra spillage, drill a hole using a 7/64 drill bit in the middle of the barrel head. Quickly but gently hammer in the 1-1/2" nail. (McMaster-Carr Type 316 Stainless Steel Nail, 4D, 1-½ length) Wax around the nail if it keeps weeping. To pull a sample, remove the nail with pliers (remove the bung if there is not enough pressure), take a sample, and then hammer in the nail again. Keep 2" steel nails handy in case the hole in the barrel head starts to get too big. (McMaster-Carr Type 316 Stainless Steel Nail, 6D, 2 length) Topping off (Angel s share). Brew more than will fit in the barrel and use the excess to top off while aging. Watch out for acetic acid (vinegar character), usually the result of too much oxygen exposure. Sanitized turkey baster, wine thief or Vinnie nail:
Progression Try to take advantage of the current character of the beer Dark, strong beer Lighter beer that can use some oak character Still lighter beer - a lightly-oaked pilsener can be wonderful! Transition to sours - but not back to clean beers! Keep detailed notes! Keep a log of what has gone through the barrel, how often it was topped off, temperature it was stored at, how long it was in contact, tasting notes and any other anecdotes.
Fermentation Most breweries move beer into barrels after primary fermentation is complete. But yeast enzymes and components in the wood can create flavors similar to roasted coffee. Many sour beers (Belgian lambics, especially) are fermented entirely in oak.
Racking out With a newer (to you) barrel, sample frequently so as not to over-oak or extract too much spirit character. Rack to a keg when it s at the right level for your taste. You may want to let it go just a bit over, particularly if it s intended for competition, as the barrel character will mellow and fade somewhat over time. Gravity, low port, bulldog, pressurized racking cane or pump.
Storage Empty Full NOTE: Proceed with extreme caution! Fill ⅔ with water, then add.13 ounces per gallon citric acid and.017 ounces per gallon potassium metabisulfite (based on total volume of barrel), then fill the rest of the way to ensure even mixing of storage solution. Check barrel once a month and change solution as needed. The barrel should be intensely sprayed and rinsed prior to use, not just filled with hot water and dumped. Burn a sulfur stick, wick or disk in the barrel. Leave to burn for a few minutes, remove and bung the barrel for storage. Repeat every 40-50 days. DO NOT burn sulfur in a spirits barrel, as there is risk of explosion.
Solera Fill the barrel with some beer, say a saison for example. Empty ⅔ (or some other fraction) of the barrel into kegs or bottles or whatever, and refill with fresh wort, either already fermented cleanly, or allow to ferment in the barrel. Take notes along the way, as the character will drift and you may need to correct for too much acidity, for example.
Resources https://www.homebrewersassociation.org/attachments/presentations/pdf/2016/homebrewcon16%20-%20small%20barrel%20strategies.pdf http://www.homebrewersassociation.org/attachments/presentations/pdf/2014/musing%20on%20barrel%20aging%20from%20a%20homebrewer.pdf https://beerandbrewing.com/dictionary/h63pzw6odq/barrel-aging/ http://www.milkthefunk.com/wiki/barrel http://www.homebrewtalk.com/selecting-oak-varieties-shapes.html https://www.reddit.com/r/homebrewing/comments/4m748p/advanced_topics_thursday_wood_and_wood_aging/ http://brooklynbrewshop.com/themash/barrel-aging-your-beer-the-5-factors-to-consider-before-you-start/ https://abeerdiary.wordpress.com/2014/07/07/my-pressure-racking-cane/ American Sour Beers - Michael Tonsmeire Wood & Beer: A Brewer s Guide - Dick Cantwell and Peter Bouckaert