The use of oak barrels in winemaking is curiously not much talked about outside winemaker and cooper circles. In the industry most of us sweep it all away, preferring to talk about the vineyard – the terroir, the grapes. At most we talk about the wine`s duration in barrel, a steer to its oak-aged style. We might even reference the extent to which new oak has been used: “The newer the oak, the more it gives, until finally it is spent and useful only as a holding vessel”. Today, however, I will expand briefly on cooperage itself. First, the basics: Winemakers choose the type of oak barrels according to the wine they want to make. Oak hewn from the northerly flank of a forest might have tight grains due to slow growth, as compared to the more open-grained, faster growing oak trees on the forest`s south side. The first, as a barrel, ensures a wine matures slowly, imparting its tannins and flavour compounds to the wine slowing, barely even, smoothening it out over the years without excess. The open-grained barrel gives far more, far quicker. The oak changes the wine fundamentally, contributing first and foremost vanilla and spices. Coopers offer a range of barrels with differing properties, and they offer a variety of charring options as well: light-toast, medium-toast, heavy-toast. The more toasting there is, the bigger the flavours it imparts, of chocolate, mocha, coffee, smoke and toast. And the choices are far more nuanced now days, with winemakers and coopers often working closely together to achieve the best possible wines. But there is another element, facilitated by oak and key to wine`s aging development, and that`s wine`s slow interaction with air: evaporation and oxygenation. Oak`s porous nature concentrates wine, while softening the tannins. It`s not the only wood used in winemaking, but it`s the best, the most widely used and the most expensive. Next time you smell vanilla or toast in your wine, spare a thought for the unsung hero of winemaking: the cooper.