This is a rough guide to help you with your barrel. Keep in mind all barrels are different and some may require you to get your hands dirty and start googling potential fixes.
Anatomy of a Barrel
First off let's start out with some basic barrel terminology. First off these actually are not barrels they are casks but that is not important.
Head: Ends of the barrel. Each barrel has 2 heads
Stave: The slats of wood running from 1 head to the other
Cant: Stave but on the heads
Stave Joint: Space between staves
Hoop: The metal used to hold the staves together and give the barrel its Shape
Bilge: Also known as the belly, the widest part of the barrel. The Bung hole is along the
Bung hole: Where the bung goes and where liquid comes in/goes out located on the bilge
Rivet: The metal device used to keep the hoops together in a circle
Croze: a groove cut into the stave that keeps the head in place
Chime: The angled part of the stave on either end that leads to the croze
Our barrels are 5 gallon barrels from Reservoir Distillery in Richmond Virginia. They are constructed out of American White Oak and charred on the inside. They previously held an award winning whisky from Reservoir. The staves and cants should be ~⅞” thick. Expect notes of cinnamon, maple syrup, vanilla and caramel.
American Whiskey barrels are built way differently than wine barrels as these barrels are supposed to be used once and replaced. Because of this, extra attention to maintenance is needed. More on this and how to below. These barrels are also charred like all whisk(e)y unlike the toasted barrels used for wine.
Barrels should always be stored wet (full of liquid). If they are not they can begin to dry and cause problems that will require maintenance. If you cannot store the barrel wet it is strongly suggested that you wrap it thoroughly with cling wrap. A few layers of the stuff from your kitchen will help immensely.
If you cannot fill for a while the barrel should be filled full with a storage solution (10 grams potassium metabisulfite and 5 grams of citric acid/5 gal of water). However this will require a goods rinse to make sure there are no flavours carried to the intended aging beverage. A fresh whiskey barrel wrapped in cling wrap tightly can stay hydrated for +2 weeks. It is not recommended, but it has been heard of places storing barrels like this for several months.
Wine Producers often store their barrels by burning a sulphur stick in them and bunging them up. DO NOT DO THIS WITH SPIRIT BARRELS. Those vapours are flammable and potentially explosive. Unless you like the idea of various sized splinters being shot into you - keep fire away from this barrel.
Prior to filling with your intended aging beverage, barrels should be checked for leaks caused by drying from shipping. The best way to do this is to wrap the barrel staves in cling wrap (tightly) and set it on its head. Fill the head up like a dish with water. Come back the following day to see if the water is gone. If it is - you have a leak. Repeat on the other head. The most likely area to have a leak on your barrel is on the head in the croze.
Barrels this small also tend to let a lot more O2 into your beer than full sized barrels (volume:surface area). To counteract the impending O2, it is recommended that you wax the top ¼ + heads of your barrel (or the entire thing) with paraffin wax. Beeswax has also been reported to work well. See the below link for a how to.
Because this is a spirit barrel there is little risk of it being contaminated with wild yeast, bacteria or mold. However, it is still recommended to give a sniff and a visual inspection with a flashlight. If mold is clearly present see below for troubleshooting.
If you have made it this far without needing to reference the troubleshooting section then you are golden! Make sure you have a beverage appropriate for this use. Finishing wine in whisk(e)y casks has started to become popular. Heck you could buy a bunch of white whisk(e)y or gin in here to age. Barrel aged meads are absolutely delicious. Imperial Stouts and Barley wines too are excellent. If you have not noticed there is a bit of a theme. Higher ABV beverages are best and strongly flavoured beverages.
Before barreling you beer should be at final gravity. Unless you want a mess and a lower yield. Rack off trub/yeast cake into the barrel, age and then package.
For aging beer you should look for something that is more malt forward, imperial and a style that ages well in bottles. The classic Whiskey barrel aged Russian imperial stout comes to mind. One thing to be aware of is the increased surface area to volume ratio. These barrels will flavour beverages at an accelerated rate compared to standard barrels.
A Vinnie Nail is a great tool for sampling the beverage while it ages without opening the barrel. Stainless steel nails are not easy to come by in small amounts in Canada so a stainless screw is best/easiest. 2” is fine. Drill into the barrel on the center of the center cant on one head about ¾ of the way down. Unscrew to collect a sample and rescrew to plug it again. Screwdriver can work but a drill is best.
Taste after a month and then doing so weekly. 4-6 weeks is usually the right amount of time for this size. These barrels will give flavour for a few cycles. Afterwards can can always “re-season” with a bottle of the spirit you want.
Long Term Care
For re-seasoning rinse the barrel until the water runs clear. Afterwards add a 750 ml bottle of whatever you want. Tequila, Bourbon, Rum or whatever tickles your fancy. Put a solid bung in and swish daily while rotating 30 degrees each day as well as doing both heads. Afterwards either leave the spirit in or drain out. It can be tasty if you filter it through a coffee filter! For more oak some cubes can go a long way.
After each fill you run the risk of possibly getting an infection. Microbes love to live in wood! Brett can penetrate more than 5 mm into american oak. Steaming is recommended every few turns or turning it into a sour/funk vessel.
If you are interested in using your barrel as a souring vessel, it is recommended to first run a few clean beers through it. Options like a RIS or Belgian Quad will help to strip the intense barrel character. You can choose to dechar the barrel (below in the troubleshooting section) or keep it with char. It is also recommended to more thoroughly wax the barrel for long term aging. Beers should generally not sit any longer than 6 months because of the surface area:volume ratio, though let sampling be your guide. To inoculate the barrel, add your microbes directly to the barrel when you rack the beer in and then it’s time to wait. Once FG is reached and it is tasting right take it out of the barrel and package or fruit. You can directly fruit in the barrel but getting the fruit back out can be a huge pain. Taste and take reading on these beers once a month or so from the Vinnie Nail.
Problem: My barrel is leaking!
Solution: Find the source of the leak. Hopefully you found this prior to filling with your beverage. Steaming or swelling with water can help rehydrate the barrel to stop the leaks. This also can strip some character from the barrel but you can always re-season therm as mentioned above. If that does not work you may need to tighten the hoops. As you can see this guy loosening the hoops here (https://www.youtube.com/watch?v=POo1Yu5aYbs) you can do the opposite and try to tighten them. You man need to use a spile. Here you can see someone repairing a leak along a stave with some (https://www.youtube.com/watch?v=R1zMcz1isLc). If you run into a particularly fussy leak you may need to do some more research to find an exact fix. Google will be your best friend.
Problem: I want to dechar my barrel!
Solution: See the above youtube video about knocking a barrel apart. Before doing so number every stave in order (heads should stay together) and with a number on each end of the stave correlating with that same head. Knock apart, sand/scrap the char off, knock back together and test for leakes. It is highly recommend steaming to rehydrate before checking for leaks.
Problem: My beverage is infected/has a pellicle!
Solution: This happens from time to time. Either dump it, let it ride to FG or pitch some other bugs with it. Once done either dedicate the barrel for funky/sour beer or fill with boiling water and let it rest for 20-30 min.
Problem: My barrel smells moldy!
Solution: Fill with boiling water. It is probably best to knock it apart as well and check. If there is mold scrub scrub scrub it away. Put back together and fill with boiling and thoroughly rinse it, re-season and carry on.
Problem: My beer smells and taste like vinegar and/or nail polish remover?
Solution: This is a common off flavour found in barrel aged beers with brett in them. There is no coming back from this flavour. Once it is there it is staying. Unfortunately the only way to deal is either blending out (no recommended) or dumping the batch.
Each barrel is unique and can have its own unique issues Check out the Milk the Funk wiki page on barrels as well as google and watch lots of videos.
It may sound like barrels are a nightmare but with the proper maintenance and care you should never have to troubleshoot anything.