Why are wine barrels toasted?

The staves – i.e. the individual planks – are only held together with metal hoops. How does it not leak? Well, to make the staves pliable enough to seamlessly join together, the cooper uses heat. He splays the half-finished barrels over a small gas fire and burns them from the inside out. This process is called toasting. It doesn’t just make the staves pliable enough to be bent together, it also imparts additional aromas to the wine, such as vanilla, coffee or cocoa, tobacco, clove and coconut. The winemaker can have a say in how strongly the barrels should be toasted – the stronger the toasting, the stronger the aromatic effect.