Why winemakers use oak
Oak barrels do two things at once: they add flavour (vanilla, spice, toast, sometimes coconut) and they let in a tiny amount of air, which softens and matures the wine.
- New oak gives strong flavour; old oak gives mostly gentle oxygen.
- French oak = subtle, spicy; American oak = bolder, vanilla/coconut.
- Heavier 'toast' (charring) inside the barrel = more toasty, smoky notes.
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Oak is seasoning
Like salt in cooking, oak should support the wine, not drown it. Over-oaked wine tastes of sawdust and vanilla rather than fruit.