Oak ageing is an art. The barrels a winemaker chooses have a marked effect on how the wine will taste, lending flavours that range from sweet to austere, says Margaret Rand.

Every wine has a back-story. We’re accustomed to tracing a wine’s history back to the unbroken grape, then shrinking and greening the grape on the vine to a hard speck, and then watching the flowering. Is it early? Late? Homogenous? It’s how we explain why wine tastes the way it does.

But from the moment we reach the barrel in which the wine is aged, there’s another back-story. It branches to the cooperage – to the fire that toasts the wood, to a cooper examining the grain, to the ageing of the staves in the rain and the wind, to an oak tree growing straight in a French forest. In the first story we ask, which vineyard? Which winemaker? When it comes to oak, we ask, which forest? Which cooper?

If you’re a winemaker, the second question is more vital than the first. If you’re a winemaker, all forests look alike. And yet the barrels you buy from Taransaud, say, are different to those you buy from, say, Boutes or Sylvain, and they make the wine taste different. Really extraordinarily different.

House style

A quick, simplistic summary: Taransaud barrels are reckoned by winemakers to make wine taste less seductive in youth than others, but are excellent in the long term – they’re powerful, a little austere. You might use them for your grand vin, maybe less so for your earlier-drinking second wine; Boutes might be better for that. Nadalié barrels give a certain sweetness. Sylvain is somewhere in between. Mercurey gives a lovely balance between fruit and wood. Seguin-Moreau is fairly similar to Taransaud. And that’s to name only a fraction of the coopers, and to ignore the subtlety with which coopers can adjust their barrels to suit your wine.

What you want, whether you’re buying a barrel or a suit, is something that fits. Your terroir, your blend of grapes, and what you are trying to achieve or express, is unique. Serious châteaux do not buy barrels off the peg. They invite their coopers along to taste their wines – the day I spoke to Véronique Sanders of Haut-Bailly she’d spent the morning doing just that, discussing with all seven of them her terroir and her grapes and the intricacies of her wine. ‘There were tiny differences between [the wines of] the different coopers; the differences were much greater a few years ago. There was a feeling that they all understand what we want.’

When the cooper understands the wine, he can suggest the right wood for it. The number of variables is mind-boggling. There’s the forest, which is usually linked to the sort of grain, but different parts of the same forest – and even different trees in the same part of said forest – may have very different grains. Basically, a tight grain from a slow-growing tree will give more elegance and less tannin; a more open grain from a faster-growing tree will give more tannins and less fruit aroma. Some winemakers have favourite forests as well as favourite coopers, but even here the cooper counts.

‘All coopers have access to the same forests, so barrels should be more or less the same, but they’re not’ says Benjamin Sichel of Château Angludet. Benjamin had been saying to Tonnellerie St-Martin that the wood needed to integrate better into his wine. ‘He said: “We have to try the forest of Jupilles” [near Le Mans]. I didn’t know it before, but I tried it and I always ask for it from him now. He tells me I’m his only client asking for 100% Jupilles. In our wine it integrates the complexity without overpowering the wine. But on its own it’s too much, and misses something. Barrels from Tonnellerie Taransaud complement it.’

A blend of coopers is always best, complementing not only different aspects of the same wine, but also different grape varieties from different terroirs. Eric Murisasco, technical director at JP Moueix, likes Remond and Taransaud barrels for the limestone of Château Bélair-Monange, and Demptos and Seguin- Moreau for the clay of Château Trotanoy. Three or four different coopers is probably the minimum, plus one or two new ones on trial. There doesn’t seem to be a big difference in approach between Right and Left Banks. When I asked John Kolasa if he treated the Merlot of Château Canon differently to the Cabernet Sauvignon of Rauzan-Ségla, he said: ‘It’s Merlot on the plateau of St-Emilion, with power and structure. If you want Vivaldi, it’s different to wanting Beethoven.’

Chewing on wood

Fabien Teitgen, technical director at Château Smith Haut Lafitte, goes a step further. The château has its own cooperage on site, so he chooses the wood. ‘When the wood is split open you can see the grain. And the smell is very important. You get an idea of the style of the wood from the smell. I chew it too, to feel the tannins, to see if they’re dry, and to judge the aromatics. From that I decide what to buy.’

Ageing is another variable – are the staves aged out in the open for one year, two years, three, or even longer? What happens in ageing is not only that rain washes tannins from the wood but also that enzymes develop in the wood, and those enzymes affect aromas. Camille Poupon of Tonnellerie Sylvain says: ‘Aquitaine has a maritime climate, so the ageing is faster than in, say, California. Two to three years in a maritime climate is enough to wash the tannins.’ Two years’ ageing gives a different result to three years. Again, it’s all about what suits your wine.

First you need rain, and then fire. The toast of a barrel (done by lighting a fire inside the half-finished barrel) comes in different grades: light, medium, medium+, heavy…. The heavier the toast, the more pronounced the flavours of chocolate, coffee and what the French call ‘torrefaction’ – roasted flavours – you’ll get. But you’ll also get less wood flavour. A heavier toast means less aroma and less finesse. With a lower toast you get more wine flavour but also more wood flavour. Complicated? Yes, very.

Most winemakers settle for more-or-less medium toast, but every cooper will have its own version of that. A short, hot toast will give different results to a longer, slower toast, even if both are called ‘medium’. A longer, slower toast gets further into the wood and gives more subtlety, more sweetness. ‘You get different flavours with different temperatures,’ says Véronique Dausse, general director of Château Phélan Ségur. ‘Burnt wood is not just burnt wood.’ Sichel was interested in low toast, ‘to gain more complexity. But coopers don’t like low toast because it only works on wood which is perfectly matured. And low toast integrates less well with the wine.’

We’re back to the fit. That integration of wood with wine is the nub of the matter. Sanders compares the perfect barrel to a Diane von Furstenberg wrap dress: ‘It shows off your femininity, it’s extremely comfortable and doesn’t hide anything, and it fits and flatters.’ And actually, like a dress, you can try it on and change your mind – sometimes.

Tasting samples of the same wine from different coopers after 18 months’ ageing shows just how different the results are. Taste wines after just 10 days in barrel and you can already see the direction in which they are travelling – they’re branching away from each other, some to opulence, some to structure. At Phélan Ségur, Dausse and her staff taste all the barrels when the wine has been in them for just two hours. That’s enough to tell them if the combination of wood and wine is going to work. If not, they can change the combination. It’s a fair old task, because it involves several hundred barrels; but if it’s necessary (‘We’ve done it a couple of times’) they’ll do it. With a top-quality, new French barrique costing €600-€700 (£500-£575), it’s too expensive a story to get wrong.

Written by Margaret Rand