Making Barrel-Aged Homebrews

I started barrel aging beer over a decade ago after attending a National Homebrewers Conference. It is amazing to watch the trend start up again with the little guys and trickle up to large production breweries. Now every big brewery has some variation of a whiskey stout this or a double bourbon barrel aged that.

Barrel aging beer is not a new trend, but it does seem to be one that goes in and out of fashion. Simply put, making beer in barrels sounds cool, but it is not as easy as just putting beer in a barrel. The easier route, especially on a small scale, is to add wood cubes, chips, planks, or spirals to achieve similar flavors. But there is something about working with a real wooden barrel that makes a beer exciting.

Barrels are fickle objects and must be dealt with quickly after a distiller, vintner, or brewer has dispatched its contents. The fresher the barrel, the more moisture content is locked in the wood. That liquid (wine or spirit) is what keeps a liquid-tight seal on the barrel and also contributes its own flavor to the beer.

The wood adds additional aromas and flavor components such as vanillin, tannins, spice, and toast that homebrewers can use to their advantage. Many craft breweries have barrel programs dealing in wine and liquor barrel-aged brews. The barrels they use usually range from 55 to 65 gallons (208 to 246 L) and are sourced from major liquor distilleries, barrel brokers and vineyards from across the country. These larger barrels are normally too large for homebrewers, unless you are having a club brew session to help fill it up (which is a very fun group project by the way).

The increasing availability of (5- to 15-gallon/19- to 57-L) American and French oak barrels are making it easier for homebrewers to create an authentic barrel-aged beer at home. You can find these smaller barrels on various homebrew websites, as well as some larger or better-stocked local homebrew retailers. Many distillers across the country are choosing to age their whiskey, rum, and bourbon in smaller barrels because of the higher surface-to-volume ratio. Distillers can age their spirits for six months instead of 12 months and achieve the similar flavor profiles. This is advantageous for the brewer also, as the rate at which the beer absorbs the flavors from the oak in smaller barrels is much greater than the rate in larger barrels. As a result, beer aged in smaller oak barrels may become over-oaked if not watched (tasted) often to achieve the perfect balance.

Barrel Anatomy

There are a few parts that make up a wooden barrel. The wood slats (staves) are cut to specific shapes in order for the wood worker (cooper) to be able to form the barrel’s shape. The staves are put on their ends in a temporary hoop and toasted over a burning bucket of wood.

The wood is heat steamed by applying water to the interior and exterior then bent slowly until it reaches the desired shape. Barrel caps (heads) are assembled using staves and cut into their circular shape. The heads and riveted metal ring (hoops) are then put into place with special coopering tools. Finally a hole is drilled through a strong stave for a cork (bung).

The wood chosen for making barrels must be mature, straight, and knot-free. Wood that is low in sap is also ideal. White oak is traditionally used due to its pliability and tight grain composition.

Once the barrels have been assembled, the cooper will sand, plane, and polish the exterior. The barrels are filled with water to check for leaks, and after passing inspection the barrels are ready.

Preparation for Use

Barrels are an ideal breeding ground for wild yeast and bugs (bacteria), so when a new barrel arrives at your doorstep, especially one used for winemaking or brewing, you need to hit it with hot water as soon as possible to keep the microorganisms under control. The hot water bath will kill off some surface bacteria and wild yeast, but not those found deep in the porous wood.

First Use Barrel Prep List:
1. Inspect the barrel for damage or leaks
2. Fill barrel with 140–185 °F (60–85 °C) water
3. Soak barrel for 60 minutes
4. Clean exterior of barrel with Powdered Brewery Wash (PBW)
5. Dump barrel contents and fill with fresh wort

Dry Barrels

If your barrel is dried out, and you find after filling it that it is leaking, you can submerge the barrel in water for 24 hours and the wood should swell back up (see photo below). Ratchet straps can come in handy for holding together loose staves and heads during the re-swelling process.

Fermenting in Barrels

Once your wort has been inoculated in the barrel it is best to keep it fitted with an airlock or barrel blowoff assembly (see photo below). Beer fermenting in wooden barrels gets very active causing high kräusens, and some beer will go through the airlock or blowoff and beer will be lost. You will need to top off the barrels after the initial round of fermentation to reduce exposure to airborne contaminants and oxygen in the barrel headspace. It helps to brew an additional round of wort, or a larger initial batch (fermenting the rest in a carboy), for topping barrels off. If you find yourself without additional wort for topping off, you can use sterilized marbles to displace the beer and reduce air exposure inside the barrel.

Barrels can be fermented in a large range of temperatures. You can cold ferment barreled beer or ferment barreled beer at high temperatures. Most beers are fermented at cellaring temperatures, but this is not necessary for all styles.


As your beer ferments you should taste it periodically. Don’t open the bung and pull a sample with a wine thief (a tube winemakers use to extract a sample from a barrel). This opens the barrel up to oxygen (which causes oxidation in beer).

Instead, use a stainless steel nail (Vinnie Nail) in the barrel head to create a sampling port. (Pre-drill the hole before filling, so you don’t split the wood.) See the photo below for an example. Drill a hole using a 7⁄64-inch drill bit on the bottom of the barrel head (6 o’ clock position).

Have two sizes of stainless steel nails on hand from McMaster-Carr:
•1–1⁄2-inch 4d smooth common nail–316 stainless steel #97990A102
•2-inch 6d smooth common nail-316 stainless steel #97990A104

Aging in Barrels

After primary and secondary fermen-tations have finished, depending on the style, it is time to barrel age your homebrew. Beer can be aged for varying times depending on the beer style and maturation period needed.

As the brewer, you can age anywhere from two weeks to many years. The smaller homebrew-style barrels tend to impart oak flavor much quicker due to the surface ratio, so a few weeks to a month is usually enough. It takes at least six months for the Brettanomyces (wild yeast) to show any signs of the work it has been doing, and Lactobacillus and Pediococcus (bacteria) are not much faster, depending on the strain. Some of the most common beer styles for barrel aging include:
Wild ale
Double IPA
Imperial porter
Imperial stout
Strong ale
Belgian blonde
Belgian quad
Belgian tripel
Belgian dubbel
Grand cru
Imperial brown
Imperial pumpkin
Imperial red ale
Winter warmer
Holiday/spiced ale

Transferring Beer

You can use gravity and auto-siphon beer out of a barrel and into bottles or kegs, but you expose the beer to more oxygen. I made a small gas barrel transfer tool for a true closed transfer with limited exposure to O2. With just a few parts you can transfer beer from barrel to bottle or keg using CO2.

Cleaning and Storing Barrels

Once you have transferred the beer out of the barrel it is time for cleaning. The best way to keep an oak barrel clean is to always have it filled with beer. It is a good idea to plan your barrel aged beer program schedule in advance so you always have a new beer ready to fill the barrel as soon as you empty it.

Flush the barrel with warm water to remove the left over trub and fill  it immediately with a new beer. Flushing the barrel with hot water should kill off a good portion of the microbial flora that coats barrel walls and outer barrel surfaces.


If you do not have a new beer ready to fill the barrel then you should fill the barrel with hot water and let it soak for an hour. Dump the water, cap (bung) and store the barrel in a cool dark place.

If you have the ability, inject a CO2 blanket into the barrel to retard microbial growth. As barrels breathe the CO2 will dissipate, so repeat the process as necessary during long storage sessions.

Most professional brewers do not recommend storing empty barrels. It is just a matter of time before the barrels dry out or become overrun with wild yeast or bacteria. Some professional brewers use a hot steam system to sanitize their barrels, but this is not very practical on a homebrew scale.

Do not store barrels filled with water for an extended period of time. This is a breeding ground for barrel bacteria like Acetobacter. I also don’t recommend using chemicals for storage purposes.

Separate Equipment

Remember that any piece of equipment that comes in contact with a sour beer in your homebrewery should be isolated from any “clean” brewing in the future. Brett, Lacto and Pedio are very resilient and are difficult to completely sanitize off equipment. If you don’t do this you may end up with every beer you make being a sour beer. Isolate plastic transfer hoses, airlocks, bungs, connectors, glass/plastic carboys, transfer gaskets and siphons. Basically any soft rubber parts should not be used again for clean brewing in the future.

A great book on brewing with barrels, wild yeast, and microorg-anisms is Wild Brews: Beer Beyond
the Influence of Brewer’s Yeast by Jeff Sparrow (Brewers Publications, 2005). There is a nice chapter on
how to manage a barrel and more than enough information for a homebrewer to be successful making their own barrel aged beer at home. Another book that I recommend is American Sour Beers: Innovative Techniques for Mixed Fermentations (Brewers Publications, 2014), written by The Mad Fermentationist (and BYO “Advanced Brewing” columnist), Michael Tonsmeire.

Barrel Questions and Answers with Professional Brewers

For a larger scale perspective on barrel aging, I sat down with Josh Hare of Hops & Grain Brewing and Joe Mohrfeld of Pinthouse Pizza Brew-pub (both in Austin, Texas) to discuss their barrel programs, and got some insight from these two passionate homebrewers turned pro.

The first is Josh Hare, the founder of Hops & Grain Brewing, who has been homebrewing beer since he was 17, and came to Austin via Boulder, Colorado where he trained and competed as a triathlete. He opened the brewery, which focuses on sustainable practices, in Austin in 2011.
“Create a beer for the barrels, not the other way around.”
– Josh Hare, Hops & Grain Brewing

Q: How can a first-time barrel user get good results from a barrel?

A: A homebrew recipe you may have success fermenting/aging in steel or plastic could curtail or amplify flavors you weren’t expecting in a barrel, so I recommend that you taste as you go. Whether you are going for a clean or sour beer it is always good to keep some type of flavor stage journal. We (Hops & Grain) created a series of flavor stages for our sour (Bret-tanomyces) barrel program that includes descriptors of taste and aroma. It has really helped us identify where the beer is at any point during the aging process.

Once you get familiar identifying the stages fermenting wild yeast goes through you will quickly know where your beer is in the aging/souring process. Brett (wild yeast) goes through many phases, during which some kick off horrible aromas like wet barnyard and dirty diapers. This is what I call the rank stage. Wait a few more months and it all changes.

Q: How long should a beer be aged in a barrel?

A: Patience is key in any barrel project. Most beers are put in the barrels and sealed off for four to six months. Some beers finish quicker than others, so it is just a matter of tasting the beers and determining if they are finished.

Q: Can an oak barrel be used more than once?

A: Oh yeah, two to three times for clean beers and then infinite sours. If souring with wild yeast and bacteria in a barrel, keep all your transfer equipment separate from equipment used for clean beer transfers. A wild barrel can never be fully cleaned for brewing a regular brewer’s yeast beer again.

Q: Is fermenting in a barrel OK?

A: Use a tight fitting blow off tube if you are fermenting in the barrel and run it into something like
a bucket of sanitizer and you should be alright.

Q: What else should a homebrewer do before bottling or kegging barrel beer?

A: With barrel beers I find that carbonation only intensifies the barrel aromatics. Sometimes I think an aroma or flavor is low-key until I carb up the beer and then POW. Just remember that when you are doing your sampling. You can try ratio blending a small sample with CO2 when doing your final tasting, so you don’t ruin a whole batch.

Now on to Joe Mohrfeld. A transplant from the Odell Brewing Company in Colorado, Joe recently set up shop in Austin, Texas as the Head Brewer at Pinthouse Pizza Brewpub. Joe is no stranger to brewing beer in barrels. At Odell he managed their ever changing wood-aged beer list and wood cut series. He is growing the Pint House Pizza wood-aged beer list with his latest barrel offering, Jaguar Shark — an imperial stout aged in Wild Turkey barrels. Joe was kind enough to share some of his best practices when it comes to brewing with barrels.

“Just because beer goes in a barrel doesn’t mean it’s going to be good.”
– Joe Mohrfeld, Pinthouse Pizza Brewpub

Q: Most important step when brewing with barrels?

A: A clean barrel inside and outside is important, but the date you get the barrel really determines how you should treat it. If the barrel is wet then it’s probably ok. I like to get a barrel within two weeks of it being dumped. I flush the barrel with 180 °F (82 °C) water for 45 minutes and clean the outside of the barrel with PBW.

Q: Do you ever have to store any barrels unfilled?

A: I really don’t store barrels unused, but if I had to then I would not keep them full of water. I would store them closed after a steam or hot water flush and possibly hit it with a CO2 blanket.

Q: A barrel is falling apart or leaking. What do you do?

A: Ratchet straps are your friend. Have loose staves? Ratchet strap. Using the barrel as a pressurized cask for serving? Ratchet strap the heads. You can use the straps to hold a
barrel together if you need to re-swell it too.

Q: How long do you normally age beer in barrels and how long before retiring or making it a permanent sour barrel?

A: Most information circulating on aging time is never true and is a big generalization. To be really good at this you have to actively manage the barrel. I taste the beer one week after filling to see where we are and leave beer in the barrel for two to two and a half months on average. Just because beer goes in a barrel doesn’t mean it’s going to be good when it comes out, so I use the barrels one or two times on clean fermentations and then five or six times for sours.

If when you find that your barrel is dried out, which can lead to leaking between the staves, submerge it in water for 24 hours and the wood should swell back up.

Just like fermenting in carboys, when fermenting in barrels you need to keep your homebrew protected with an airlock and bung to prevent exposure to air.

To prevent exposing your homebrew to air when sampling, drill a small hole and use a stainless steel nail to make a sampling port that you can easily open and close.

Barrel Transfer Tool

Parts List

Double drilled #6.5 stopper
Stainless racking cane
¼-inch flare/barb fitting for gas
Hose clamps
Gas line
Beer line

Step by step

1. Clean and sanitize all parts of the barrel transfer assembly (tool), exterior of the barrel and whatever you are transferring into.

2. Purge receiving vessel with CO2 to reduce oxygen exposure.

3. Insert barrel assembly tool into barrel and secure stopper.

4. Attach CO2 line to the inlet on the stopper.

5. Adjust PSI to 1-2 PSI or just until beer/wort starts to flow at a slow pace.

6. Fill receiving vessel(s).

Issue: May-June 2015