More on Wood and Barrels!

Please,  read the iStill Blog post “Odin’s got Wood!” first! Otherwise you will miss out on half of the story.

Synopsis so far …

Barrels are responsible for 50 to 65% of the taste of your whiskey. Barrels are made from oak. Not all oak is created equal. If you want sweetness and vanila, choose American White Oak. If you want character and complexity, you need European Oak (EUO). Which barrels you need, if character and complexity is your goal? The ones made from European Winter Oak from Hungary’s Zemplén region. That’s the best “terroir”.

But there’s more. We didn’t dive into the role of the Master Cooper yet. And what age should the trees be, that are used by these Master Coopers? How should they be treated? What size barrel do you need, and what are the advantages and disadvantages of charring and toasting? Stay with me and let’s dive in deeper!

The Master Cooper’s Role

It is important to understand the difference between a Cooper and a Master Cooper. Where the Cooper makes barrels, it is the Master Cooper that decides which Cooper makes what part of the barrel. Who does the cleaving? Who makes the staves? Which Cooper is best at building up the barrel? And who does the toasting? The Master trains his employees and puts them to work. Important? Yes, but there’s more …

First of all, it is the Master Cooper that decides on what wood to use. Secondly, he decides how the production process is organized.

The Master Cooper personally visits the forests and selects the trees he wants to buy. This is an extremely important part of the whole oak to barrel to whiskey process. A well-experienced Master Cooper, that probably learned the trade from his father and grandfather, will select better trees in order to be able to make better barrels. And a well-connected Master Cooper gets the first choice on trees that become available.

When the trees are selected, cut down, and brought over to the cooperage, the Master Cooper has to decide on how to cut trunks into staves and how to age them. He has to be able to forecast demand for around 5 years ahead and plan accordingly. In short? This is not a low entry level profession!

The choice for working with a specific Master Cooper may well be more important than checking the wood that’s used. The questions I’d ask myself, as a distiller, considering a certain cooperage and Master Cooper to co-operate with, would be these:

  • How long is the cooperage in existence? The longer the better!
  • Is the cooperage family owned or not? In general, it’s the family owned cooperages, that exist for a long time, which are most involved, most experienced, and best connected.
  • How big is the company? You need at least 5 to 10 employees to reap the benefits of specialization, co-ordination, and good service and after sales.
  • How involved is their workforce? Do they hit the road the moment it’s five o’clock or do they finish the task at hand and put in that extra 15 or 20 minutes?
  • How tidy is the workplace? Cleaving, sawing, sanding wood is dusty labour. For me, a tidy workplace signifies the attention to detail I am looking for.

What age the trees should be

In general, the best age is between 100 and 150 years. With the mean being something like 120 years. Older trees may start to crack or mold. Younger trees are still relatively fresh and green, and contain higher dosages of new, unaged tanins.

How the trees should be treated

Preferably, the trees and trunks should be layed to rest for a year. After that year, the trees will be cleaved and sawed into staves. The staves need to dry out, to lower the overal water content of the oak. Two years is the minimum dry out period. Three years is optimal. More than three years of drying can cause the wood to become too dry to work with.

The way the staves are dried is essential. They should dry outside, stapled and placed in such a way that the wind, the sun, and the rain have easy access. The rain rinses out some tanins. The sun dries the wood. The wind helps evaporation. An open field aligned with general wind direction is considered best.

What size barrel suits you best?

That depends on when you want to bring your product to the market! Here is a few general rules of thumb:

  1. If you want to release your product in a year, a 55 liter barrel is great;
  2. For two to three years of barrel ageing, a 110 liter barrel is perfect;
  3. Do you want to age for three to five years? Choose a 220 liter barrel!

What shape should the barrel have?

There are various styles and shapes. In general, though, a higher, more cigar shaped “barique” barrel is considered better than a wider and lower cask. The reason is that a higher and more narow design allows for more stave contact, where a wider and lower design gives more top and bottom end contact. And since the heads and bottoms are made from left over wood, and since normally only the staves are toasted … a barique design gives of more and better taste.

Toasting and Charring

Toasting is done by placing an open barrel, so without top and bottom ends, over a fire. The longer the fire is kept going, the higher the toast level. Charring is done by actually putting the inside of the barrel on fire for some time.

Toast gives off the most character. Charring creates a nice looking aligator skin on the inside of the barrel and generates slightly more colouring. In general, I would not advice charring European Oak (EUO). It may be needed in American White Oak (AWO), but not in EUO.

What level of toast is needed? Depends on the taste profile you are after and the product you are making. A higher toast level releases more wood tastes faster. And a higher toast level also creates heavier notes.

Here are some guidelines that can help you out:

  1. Heavy or Medium Plus toast for whiskey;
  2. Medium Plus or Medium toast for rum;
  3. Medium toast for brandy or Cognac;
  4. Light toast for fruit brandy and genever.

Toasting and Charring II

It is easy to decide on the toast level, if you know what product you will barrel age. See the above guidelines. But there’s another take on it. You can use barrels multiple times! Each time they are used, they give off less taste, that’s the clue. You could, for example, buy a 220 liter barrel with Heavy toast and proceed as follows:

  1. Age a whisky for thee years;
  2. Then age rum in it for three years;
  3. Then age genever or a fruit brandy in that same barrel.

The older the barrel gets, the more of the flavours it already has given up. It is as if a once Heavy toasted barrel for whiskey now becomes a Medium toast barrel for rum, and then a Light toast barrel for fruit brandy or genever.

And after the fruit brandy or genever is done, you can even decide to re-use the barrel again. You could, for instance, soak like 10 liters of Sherry or Port in that old barrel, overturning it like every second day. After a month, the Sherry or Port will be absorbed by the wood. You can now use the barrel one last time: for a three months to one year Sherry or Port finish on your Special Reserve Whiskey, Rum or Brandy!


The experience and network of the Master Cooper you work with are essential, if you want to obtain the best barrels. He will use his skills and connections to hand select the best 100 to 150 year old trees.

The barrel sizes you need depend on your ageing strategy, but 55, 110, and 220 liter sizes give you all the versatility you need. Make sure you buy barique style casks, since they impart the best tastes, and choose the toast level that goes with your product or line of products.

The journey so far …

… has been great! I have learned so much about the craft of barrel making, that I feel confident we should take the next step. The talks to so many Master Coopers has inspired me to discuss a special design, dedicated to spirits ageing instead of wine, Sherry or Port ageing. An iStill designed and approved barrel? With more quality and versatility than anything else out there? Based on the lessons I learned and shared on the iStill Blog? I think we can do that. We have come up with some intriguing innovations. I will share more information on them in another post, somewhere next week. And I will need your feedback. In the end, I want you to tell me if we should bring this to the market place or not …


Zemplén Region …

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