The true masters behind barrel aged beer!

December 15, 2015


Beer is hype; almost forgotten beer styles revive as worldwide trends (just think of IPA’s ore Sour Beers); brewers become idols – the beer world is dramatically changing. And customers start understanding the fact that beer is more than a cheap thirst quencher!


But sometimes, success forgets about some of its makers. The old technique of aging beer in wooden barrels, which is one of the rising stars in the brewing scene at this moment, is not only based on the knowhow of the brew masters around the world – they could do almost nothing without the precious craftsmanship of those building these barrels: the coopers!


Not so long ago, barrel aging was old fashioned and the cooper crafts became a vanishing species. Besides wineries and spirit producers, there was no demand for new barrels. And even they use them for such a long time that the demand could be satisfied by only few of them.

But the Craft Beer Trend has not only positive effects on the beer scene itself, a lot of connected crafts and industries benefit from it. And so do the coopers as the barrel aging beer scene needs loads of new and old vessels.


Time to look at the cooper crafts, which are mostly unknown und unfortunately unrecognized…

The profession of coopers exist for at least 900 years and their job is to build and repair wooden barrels of all sizes and for all type of liquids. Most of them were closed in order to lager beer, wine, whiskey and all other type of drinks; some of them were open in order to be used as washing barrels or water tub.

Traditionally, the vessels that were build, had a straight shape. This was easier to build in the beginning, as the techniques did not allow building the typical bulbous shape we know today. And with the further development of modern production methods and new materials, the wooden barrels – and thus the coopers – lost importance. Fortunately this has turned again and the demand for wooden vessels exceeds production nowadays.


The building itself is time consuming and needs a profound knowledge.

Almost all wooden barrels are made of oak that is mirror or half mirror cut. (This means that the wood is cut vertically or diagonally against its year rings.)

After cutting, the wood has to be air-dried. This takes (when the traditional method is used) about one year per one centimetre of wood from both sides. So a wooden plank of 4 centimetres thickness needs 2 years to dry.

The characteristic metal bands around the barrels are made of black, bare or galvanized strip steal. Copper or brass is only used for ornamental vessels - they are too weak for bigger barrels. Most commonly, the metal bands are riveted. Only sometimes they are welded.


The barrel itself consists of staves and bottoms. The wood for the staves is cooked in a traditional manner and then bent with help of a machine. Then the staves are put together to form a body that is drawn together with a winch.

Then, the bottoms are put into a groove at both ends of the staves.

Reed is used between the staves and in the grooves. Reed swells up and seals up the barrel. Its only this and the pressure that keeps the barrel together – they are not glued!

Beer barrels are built of quite thick wood (30-45 mm) and fitted with broad, strong bands. Logic, they need to resist the pressure of a secondary fermentation.

The inside of the barrels is pitched or, the modern variant, fitted with a Durolite interior trim. You can imagine, that the second variant is not really the thing you want when aging beer. It’s the tar (a natural product distilled from tree resin) that lets marry wood and liquid. Disadvantage is that these barrels have to be pitched yearly.


The synthetic Duralite interior trim does not need yearly treatment. And it’s a fine alternative if you don’t want the barrel to influence the taste of your brew. This is e.g. the case at the Oktoberfest where the wooden barrels are a part of the tradition, but today nobody wants its Oktoberfest Bier to have a wood flavour.


Wine and spirit barrels are in general made of thinner wood and weaker metal bands, as they do not need to resist pressure. And especially wine barrels are untreated at the inside in order to create the unique flavour picture of barrel aged wines – and this is exactly what the new generation of brewers is looking for.

Before they can be used, the new barrels have to be filled at one third with boiling water to ‘close’ the barrel. Therefore it is in deed closed and shaken for a while so that the boiling water can reach the entire inside. Then the water is poured, black of the resolved tannic acid from the oak wood. This procedure is repeated two or there times as the cooper wants to extract most of the tannic acid (even as it’s harmless). Then, the barrel is completely filled with clear, cold water and put aside for two weeks. Nevertheless, the water has to be changed a couple of times during these period. The longer the barrel is ‘watered’, the less of its later content will be lost.


The demand for pre-used barrels is extremely high as brewers look to capture the aromas and tastes of the previously barrelled liquids into their beers. Wines, Whiskey, Brandy, Cognac are just some of the most favourite pre-used barrels. And due to above mentioned difference between wine and spirit barrels and those built for beer, the brewers have the added problematic when they work with old wine and spirit vessels that the aged beer will lose carbonation and needs either to be re-carbonated or to be blend with ‘fresh’ beer. But mostly, the effort is worth the result. Barrel aged beers offer an uncommon richness of aromas and tastes, no wonder that these beers are so popular at the moment.


A popularity that brings with it some problematic that had to be solved. As mentioned above, pre-used barrels become quite rare and expensive. But seen the number of ‘barrel aged’ beers making their appearance, there must be another method…

Some might use new barrels and create their own flavour profile, a good thing I think. Others use wood chips. These wood chips are made of old barrels that cannot be used or repaired anymore, but that still transport all the flavours a brewer might want. So the beer is not matured in wood, but wood is added into the worth or the final beer in order to ‘flavour’ the brew.


There is nothing wrong with this method, besides that brewers shouldn’t be allowed then to mark ‘barrel aged’ on these beers. They are simply not aged in barrels (and mostly not aged at all)…

Tell your customers that you use wood chips, be transparent, and they’ll accept and appreciate that. And they’ll nevertheless love the beer!


Cheers to the coopers!

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