At Los Milics Vineyards in Sonoita, we’re hosting tastings on our crush pad while the tasting room is built. If I am not in the weeds, I give tours of the production facility. Invariably, someone asks about barrels. Questions like “Where do you get your barrels?” or “Are they all new?” are common. There are three major reasons to use oak barrels: to add aromatic and flavor compounds; allow for slow oxygen exchange through porous...