Solera Series Part 1: Planning & First Fill

fresh barrel

I’ve been itching to start my own sour solera project ever since I started making sour beer. Barrels aren’t a requirement for a solera, lots of people make them in carboys or other vessels. But I have a romantic image of barrel aged beers and wanted to try the process for myself.

Prior to this project I’d never brewed with a barrel or even seriously considered getting one. I did a lot of background reading and I want to share what I learned getting ready for my project.

Choose a barrel size

Used barrels come in a wide variety of sizes. A standard American whiskey barrel is 53 gallons. Wine barrels are typically a little larger. 60 gallons is a common size.

Smaller barrels in the 5 to 30 gallon range are also available on the used market. Most come from small whiskey producers. I’m not aware of any sources for small wine barrels or if any wineries even use small barrels. It seems that if you want a small used barrel, you’re getting a whiskey barrel.

For my project, I want the barrel to be big enough to produce a significant volume each year, while still maintaining a good average age in the barrel. A 5 gallon barrel would give a pretty wimpy output. A full size 53 gallon whiskey barrel would be difficult to fill, and produce an overwhelming amount of beer each year once it was running.

For me, a solo sour brewer, I think the ideal solera size is the 15-30 gallon range. Accounting for some evaporation and top-offs, if you pull 5 gallons once a year from a 15 gallon barrel, you’ll approach an average solera age of about 2.5 years. To run the numbers for yourself, check out this handy solera age spreadsheet from The Mad Fermentationist.

In addition to the volume of yearly beer production, another consideration in choosing a barrel is that the smaller a barrel is, the higher its surface to volume ratio. Smaller barrels impart more oak flavor faster, have higher relative evaporative losses, and allow more oxygen exposure than larger barrels. None of this is good for beer that you want to age for years.

Because of these drawbacks, it seems like the best barrel for a homebrew solera is the biggest barrel that the brewer is willing to put up with. If you have a few sour beer brewing friends, or maybe just one really ambitious sour beer friend, I think a full sized barrel is the way to go. I didn’t get a full size barrel for this project, but I hope I’ll get to try one some day.

I chose a 15 gallon barrel because that was the biggest size I could talk myself into using for a couple of high gravity clean beers, which would make the most of the barrel’s delicious whiskey character before it was moved on to sour duty.

Plan your storage

If you have a basement where the day-to-day temperature is stable, this is going to be a pretty easy step for you. For everybody else, creating a good environment to nurture a giant barrel of souring beer year round might be the hardest part of the whole sour beer-making process.

You need a space that stays in the rough range of 60-75 °F with minimal day to day temperature swings. It’s ok if there are gradual seasonal temperature changes, but large fast swings are bad. Cooler temperatures slow the sour bacteria and favor more brett funkiness. Temperatures on the warmer side will tend to produce more sourness faster but also risk increased acetic acid production.

These temperatures seem to be safe guidelines more than absolute requirements. As reported in Tonsmeire’s American Sour Beers, Dave and Becky Pyle brew award winning lambics in their un-airconditioned mid-atlantic garage!

I don’t have anywhere in my house that is naturally suitable for sour beer aging, but I solved this by installing a small portable heat pump in a closet. It can both heat and cool the closet as needed. It was kind expensive but I plan to keep my beer closet packed with conditioning beers and I don’t want to risk harming them in the natural temperatures of 50’s in the winter and 80’s in the summer.

Source a barrel

Fresher is better when it comes to used barrels. I would start by looking for local distilleries that might sell you a used barrel, or a local home brew store that has a reliable source for them.

If you have to order online, there are a lot of choices out there. Here are some of the used small barrel sellers I found in my search:

I ended up ordering a 15 gallon Dad’s Hat barrel shipped from Keystone Homebrew.

My barrel seemed pretty fresh when it arrived. There was no liquid in it, but it had an encouraging hot smell of whiskey when I opened it. Overall I had a good experience ordering from keystone and I’d use them again.

To wax or not to wax?

Since small barrels have higer surface to volume ratios and let in more oxygen than larger barrels, some people apply paraffin wax to the a portion of their barrels. The idea isn’t to completely seal the barrel, but just to reduce to oxygen transmission to a level simiar to what a full size barrel would give. Waxing also helps seal the staves at the top of the barrel, which are prone to drying and leaking during long aging.

There’s a good how-to over at Funk Factory Brewing.

I decided to wax the top ~40% of my barrel – just the staves. I left the heads alone.

Plan for top ups

To minimize oxygen in the headspace and keep the barrel well hydrated, you may want to top up occasionally. I’ve found that in my storage conditions, the 15 gallon barrel needs about half a gallon of top up every 3-4 months. Your mileage may vary.

I brewed a couple gallons of extra beer when I originally filled the barrel. It’s the same age and innoculated with the same microbes, so it shouldn’t impact the fermentability of the beer when I add it to the barrel over time.

Fill the barrel and wait

racking

You want to have the beer ready to go in when the barrel arrives. The less time the barrel spends empty, the better.

A common approach for brewing with used spirits barrels is to first age one or two strong clean beers that will benefit from the intense initial whiskey and oak character in the barrel. After aging these first beers, the barrel will be more mellow and appropriate for sour beer aging.

The clean beers I put through my barrel (Rye Barrel Stout and Rye Barrel Old Ale) were collaborations with my friend Adam. It was great to brew these beers on his 20 gallon system, and also to have someone to share 30 gallons of boozy barrel aged beer with. Cheers, Adam!

After the stout and old ale, the barrel was finally ready for solera duty. I brewed three batches of flanders red on my home system, waited for primary fermentation to finish, and racked them all into the barrel the day after packaging the old ale.

I plan to check the fill level occasionally and top up with similar beer if needed.

If it’s tasting ready, I’ll take the first 5 gallon pull at one year, approximately February 10, 2021. Fingers crossed for some good results!

Wallflower Brewing