The red wine is then aged in vat (50-200 hl stainless steel, epoxy, or concrete) or oak (foudres, and/or different-sized oak barrels). During this period (10-18 months), racking may be done one or more times. This slow and harmonious maturation makes the wine more rich and complex.
Prior to bottling (or earlier in some instances), the wine is blended, fined, and/or filtered if the winemaker so wishes. Once bottled it is, ideally, stored for 1 to 12 months to stabilize before labeling and shipment.
The oak barrel of more modest size - 225 liters in its version of Bordeaux and Burgundy 228 liters - has made its appearance in the cellar. It softens the tannins in the wine and highlights the vanilla and toasted aromas. The seek is for balance to avoid any dominance from the oak. Often only a specific selected part of the wine is aged in oak barrels (e.g. Mourvèdre and Syrah and Roussanne).
More recently, the winemakers of Chateauneuf-du-Pape use the bigger 600 liters oak barrels (demi-muid) who offer a more gradual and smooth wood contact to the wine. Especially grapes from old Grenache vines age very well in these demi-muid barrels as well do Syrah and Mourvèdre.