What are cross cut staves?
First off, the wood "paneling" part of the traditional barrel is made up of staves, which are bound together with wooden or metal hoops.
No two staves, in traditional barrels, are the same shape! They have different thicknesses, widths, lengths, and curvatures! They are traditionally flat, with little texture on the inside. Normally, the spirit, or wine, or beer, inside of the barrel interacts chemically with the wood on the outside, bringing the flavor of the wood to the liquid inside. Spirits can penetrate a flat stave ½ the depth of a human hair every 7 days.
On the other side of the coin of complexity, HONEY COMB Staves (patented barrel alternative created by Black Swan Barrels and Russ Karasch) are very intricately shaped. The particular shape of these staves maximize the rate of extraction and accelerate the aging of the process. They provide the highest surface area to volume ratio for extraction.
In the middle of these two options are cross cut staves. It's less costly than the HONEY COMB method, because the method of producing a cross cut stave is not as expensive as honey combing a stave. It provides a similar "high performance" result, but costs less!
Cross cutting exposes the “end grain” and the wood’s capillaries. This results in alcohol will moving into the wood- the same way that water and nutrients moved through the tree while it was alive. This is an incredibly efficient method of working with the wood, as it results in aging a spirit 8 times faster than traditional means! It will extract even more quickly for beer and wine, as there is a higher ratio of water to content. In fact, beer and wine will age anywhere between 10 to 20 times faster than the average aging time! We are currently in the process of testing specifically how long it takes beer and wine to age with cross cut staves, in conjunction with the University of Northern Colorado, Colorado State University, and the University of Minnesota. We are using a variety of different products and methods to test exactly what the time it takes is, but for now, very, very quickly will suffice!
The inventor of the cross cut stave, Russ Karasch, first patented the idea back in 2002. Does the name Russ seem familiar to you? It should, as Russ is also the inventor of Squarrel Barrel technology! And I mentioned his name less than a paragraph ago. Russ is a brilliant inventor, and we are very lucky to work with his brilliant concepts here at Squarrel.
Seasoning and toasting is a fascinating area of barrel-aging that not everyone is entirely familiar with! Here's a little write-up so you can soak in a bit more information.
Oak destined for barrel-making is usually seasoned-artificially or naturally-to reduce excessive humidity, undesirable aldehydes, and harsh ellagitannins. Toasting will create a variety of flavors in the wood, depending on temperature and time.
In artificial seasoning, oak planks are heated in an oven (kiln) at approximately 50 °C (122 °F) for up to one month. This is a quick and economical way of seasoning oak but it doesn’t remove as much of the undesirable components. The most expensive barrels are coopered from two- or three-year air-dried wood, which increases concentrations of aromatic compounds.
The most dramatic structural and chemical changes in the wood occur with toasting where the inside barrel surface is set over a fire or subjected to another heat source. Toasting both mellows the tannins in the wood, as well as changes the flavors the barrel might impart from raw wood to more spicy, vanilla notes—toasting actually helps release vanillin from the lignin in the wood. There are varying degrees of toasting—from a light toast to a heavy toast and, as you might imagine, that changes the way they can influence the aged liquid.
LIGHT TOAST: Provides a slight color change to the wood providing scents of vanilla, caramel and clove.
MEDIUM TOAST: Provides a brown toned wood, and imparts scents of cedar, roasted nuts, vanilla and coffee.
HEAVY TOAST: Provides a dark toned wood, and imparts aromas of coffee bean, charcoal, ginger, nutmeg and toasted bread.
Lignin, cellulose and hemicellulose (wood sugar) are essential components of oak—their chemical bonds are broken during toasting, leading each compound to break down to simpler substances. Tannins also go through a similar process, emitting free ellagic and gallic acids. With enough heat, the tannins can be completely destroyed.
Hemicellulose begins to release its basic sugar compounds, which contribute to toasty aromas. Lignin breakdown leads to the creation of vanillin, oak’s signature flavor, as well as syringaldehyde. At higher temperatures, lignin creates volatile phenols, such as guaiacol, lending smoke notes.
Toasting substantially reduces the plank-smelling aldehydes and the heat causes lignins to degrade into their volatile aldehyde and ketone derivatives. There is an increase in phenolic aldehydes and ketones and substantial production in guaiacol and syringol and their respective derivatives, all responsible for the smoky, spicy aromas. Heavy toasting also introduces little cresol, which impart a tar-like smell, 4-ethylguaiacol and 4-propylguaiacol, responsible for bacon, spice, clove or smoky aromas. It also results in ketones, which can add aromas of freshly baked bread and caramel.
Toasting also increases the amount of oak lactones responsible for flowery, spice, coconut aromas though the incremental effects of heavy vs. medium toasting are not significant. Toasting introduces furfurals or furanic aldehydes, including 5-hydroxyfurfural, which imparts caramel, bread and almond aromas, and 5-methylfurfural, which imparts notes of toasted almond.
Charring increases levels of lignin breakdown products extracted by the spirit. Although the char layer contains few aromatics, heat penetration to subsurface layers promotes thermal degradation reactions and increases aromatic aldehydes and acids to a depth of 6mm. Although deeper in the stave, the char layer does not hinder their extraction because the disruption of the wood structure during charring increases the penetration of the maturing spirit.
The grain is the sum of annual growth rings added each year in the life of a tree. Oak belongs to the family of the “ring porous” hardwoods so the early spring wood tends to be more porous to allow the flow of nutrients to the awakening tree.
Although more than 600 different oak species are found globally, only 3 species are suitable for making wine barrels. These are Quercus patraea and Quercus robur, which are mainly found in Europe and Quercus alba which is indigenous to North East America. In Europe oak trees are usually 150 years old before they are used for barrels. Contrary to that North American trees are already used after 60 years. Another important difference between the two species is the appearance of more tyloses or radial rays in American oak. It causes higher density than the European oak and consequently it can be sawn, while European oak needs to be split along the grain to prevent barrels leaking.
As result of this difference only 10 to 14 barrels can be made from a cubic meter of European oak. The utilization of American oak for barrels is 40 to 45%, compared with 20 to 30% of French oak. This is one of the reasons why American barrels are cheaper than European barrels.
Oak is the primary species used to make barrels. Its possible to create a broad variety of flavor profiles within the oak species depending on the region from which the oak is harvested, the seasoning of the wood and the toasting/charring of the barrel. There are additional species of wood used in coopering around the world that can extend the range of flavors obtained. Squarrel is committed to provide you with a breadth of wood species to best enhance your amazing craft product.
Oak contains many flavor components. The primary compounds that may influence beer are tannins, which are a type of phenol. Although brewers generally seek to minimize the amount of tannins in their wort and beer, tannins may offer benefits to cask-aged beer. It is thought that tannins act as “body-builders,” contributing to a beer’s mouthfeel. Ellagitannin and gallotannin are known to clarify wine by reacting with proteins and precipitating them out of solution; it is likely that they have a similar effect on beer. The hydrolysis and oxidation of lignin, also found in white oak, produce vanillin syringaldehyde and other compounds in alcoholic beverages during cask aging.
The most significant non-volatile compounds in raw untreated oak include: cellulose and hemicellulose which together with lignin make up the complex, strong woody matrix of tree trunks; astringent and bitter-tasting hydrolyzable tannins; coumarins; gallic acid; and small concentrations of harsh condensed tannins.
Cellulose is a very large polymer of glucose, which gives wood its structural strength. Hemicellulose is a shorter polymer of glucose and many different sugar monomers form hydrogen bonds with cellulose. And lignin fills the spaces in the cell wall between cellulose, hemicellulose and pectin components. Cellulose undergoes relatively little change during seasoning and toasting and therefore has little impact on the final aging chemistry. But hemicellulose and lignin contents are reduced with increased levels of toasting.
Hydrolyzable tannins can be hydrolyzed, or split, into their gallic and/or ellagic acid and glucose components. Those tannins from gallic acid are known as gallotannins and those from ellagic acid as ellagitannins. The class of ellagitannins is the more significant of these two and, specifically, castalagin and vescalagin are the most important ellagitannins derived from oak wood.
Coumarins in oak wood include bitter-tasting scopoline and esculin, compounds which are found bound to sugar components but which then hydrolyze to the more neutral tasting scopoletin and esculetin compounds.
European oak is known to have higher concentrations of ellagitannins and coumarins compared to American oak. Harshness and bitterness are exacerbated by gallic acid (a phenolic acid) content, which contributes an acidic taste which enhances bitterness But hydrolyzable tannins and coumarins can impart that familiar oak sweetness because these compounds can hydrolyze and release sugar molecules.
Condensed tannins, also known as proanthocyanidins, are very large catechin and epicatechin polymers which are less astringent than hydrolyzable tannins and polymerize over long periods of time to give wine its stability.
The most significant volatile compounds include: long straight-chained and phenolic aldehydes; volatile phenols; and oak lactones. In raw oak wood, long straight-chained aldehydes include high concentrations of trans-oct-2-enal, trans-non-2-enal, and decanal, 8, 9 and 10-carbon aldehydes, which are responsible for the odor known as “plank smell.”
Phenolic aldehydes are characterized by a closed-ring chemical structure; the most significant is vanillaldehyde, commonly referred to as vanillin, which is responsible for imparting vanilla-like aromas. Phenolic aldehydes in wines affect taste, color and mouthfeel. Other less significant phenolic aldehydes include syringaldehyde, coniferaldehyde and sinapaldehyde; however, these will only play an important role in toasted oak.
Volatile phenols include compounds that are most often associated with toasted oak, but in raw wood, there is only eugenol, which is responsible for aromas of cloves, and to a lesser extent, phenol.
And then there are oak lactones, namely, methyloctalactone and its variants, which are found in higher concentrations in American oak. These are responsible for sweet, spicy, woody, fresh, leather, and coconut aromas.
There is obviously a lot that goes into barrel making and wood choice, and it’s important to note that the process of making barrels has not changed in hundreds of years. Squarrel is seeking to advance a traditional process; maintaining the strength of those customs while making them more modern and environmentally friendly.
Happy Great American Beer Festival, friends and Squarrel lovers! This is an exciting time of year for everyone, from the parties, presentations, lunches, and beer releases, to the delightful and unique collaborations. We're delighted to be celebrating GABF with you!
Squarrel is lucky to be participating in SIX collaborations with some incredible local breweries! That's a lot of beer!
One of my favorite things about the Squarrel aging process is the sheer amount of variety that goes into each barrel. Since our staves are interchangeable, you can mix and match with whatever flavor works best for you! Local brewers are perhaps even more excited about it than we are, and have created some unique beers for you to try during GABF.
This week, our collaborators include Purpose Brewing, Black Bottle Brewery, Jagged Mountain Craft Brewery, Snowbank Brewing, Weldwerks Brewing Co., and Wynkoop Brewing Company. Since that's such a mouthful, we're going to break it down into individual beers!
Squarrel Barrels at Wynkoop Brewing Company
Wynkoop Brewing Company is releasing a special Sour Stave Saison with some of our White American Oak, which should be a delightfully distinctive treat during your time at GABF. Here's the event on GABF's website, just remember it's available all week, in downtown Denver!
Squarrel Barrel on Wynkoop's bar.
Next up, we have a special surprise beer at Purpose Brewing! Wow!
Purpose beer atop a lovely Squarrel Barrel.
It's a Mongolian Oak aged beer, to be released on September 20th! It's a blonde mixed culture fermentation that is slightly sour, they describe the flavor as having "notes of "dark chocolate, espresso, vanilla, cinnamon, and nutmeg. The tannin structure is more complex and earthy. Trees grow in a harsh climate and this oak is known as the 'holy grail' of Japanese whiskey barrels. The rarest of all, it leans on the brittle side." You can get it starting at 3 pm on Thursday, in one of Squarrel's hometowns, Fort Collins!
One of the brewers at Purpose, Peter, cheesing next to one of our very own Squarrel Barrels.
Weldwerks Brewing Co. is also releasing a distinctive beer of its own, it's a sake style lager that was fermented and aged in a Squarrel Barrel. You can find the event for GABF here, and Weldwerk's hours on their website, here! They're located in Greeley, so you can participate in GABF wherever you are!
A very sexy sake lager at Weldwerks!
Snowbank Brewing is releasing a Colorado Red, aged in one of our very own American Oak staved barrels! Go see them in Fort Collins, you won't regret it!
Jagged Mountain Craft Brewery is releasing TWO new beers this week in collaboration with us! First is their Oaked Wolf Pack Black Saison with Palo Santo, a very flavorful and distinctive wood that we offer. They are also featuring an Imperial Oak Aged Brut IPA with Palisade Peaches, which is a very distinctly Colorado beer. There aren't very many Palisade Peaches left this year, so why not try them out in Denver with your beer?
Here's that Peach Brut, still squirreled away in one of our Squarrels.
Last, but almost certainly not least, Fort Collin's very own Black Bottle is bringing you a maple wood aged beer, an American Oaked Pumpkin Spice Ale! If you're tired of the hot Colorado summer, come check out this autumnal ale that is sure to delight!
We're very lucky to be working with some of the best breweries all over Colorado, come celebrate GABF with us!
the trees lives and ours- past and future- are intertwined
life is a network, there is no nature or environment separate from humans
-the songs of trees, David George Haskell
each piece of wood gives itself to the spirit, beer, wine, all of its history & its experiences are all imbued into the liquid it touches
Don’t want to read 5 pages of website- well here’s a snapshot. Here’s what makes the Squarrel, the Squarrel.
We’re a group who cares a ton about wood. Like A TON.
And a we’re a group who cares deeply about what we’re drinking.
And we’re a group who loves the people and the process behind it all.
We’re basically just people for the ethical treatment of trees as natural resource.
Squarrels are square barrels. Clever, eh? They’re reusable and they’re customizable. Use them for spirits, use them for beer, use them for wine. Use them for kombucha or cider or coffee. Use them for chocolate. Use them for pickles or for hot sauce.
Squarrels are barrels, they do everything a barrel does. And ironically, their rigid structure is quite flexible.
The Squarrel happened because these 2 things happened: 1- the shortage of white oak meant there was a shortage of oak staves available for traditional barrel making. 2- there was plethora of unwanted/unused short oaks staves (consisting of the very same quality as those longer normal looking staves) being trashed by cooperages and stave mills.
Squarrel is designed to give you everything you need in a barrel while minimizing waste and maximizing our precious oak tree resource.
Yes, maybe we’re a bit tree hugger-y but guess what- we’re ok with that.
The Squarrel Situation
Its replaceable staves provide an infinite number of combinations of wood, allowing for myriads of flavor combinations. From different wood species to stave styles to treatments- every barrel is fully customizable and easily replicated at the same time.
It’s taking BYOB to a whole new level!
That’s ‘build your own barrel,’ of course. You can find more information here on our Customizability page!
From the traditional and tried and true, all the way to the experimental and progressive, Squarrel is here to help foster your creativity all while preserving our natural resources.
We love wood and all things wood related- and constantly experimenting and questioning and challenging the status quo is something else we love. So, stay tuned. Discoveries and experiments and all sorts of projects are headed your way.
Peace, love, and honor for the Oak,
The Squarrel Squad