- A quaint term that refers to the wine that goes missing from the barrel during ageing. Real world cause is evaporation through the pores and seams of the barrel. Can amount to a loss of 5% or more over a year of barrel ageing, which must be periodically topped up. Contributes to a wine’s concentration
For centuries, winemakers have turned to wooden barrels for the final ageing of their best wines. Usually made from oak, wine barrels are held together with nothing more than a few reinforcing rings -- no glue, no nails. Even the heads are sealed with simple strips of bulrush. The result is a barrel that is water-tight and very nearly air-tight. And it’s that “very nearly” part that’s important here. Microscopic spaces between the staves and the heads and around the bung hole allow a minute amount of evaporation. Over time, which ranges from a few months to several years, liquid evaporates through the various gaps in the barrel, to be replaced by air. This condenses the wine, making it richer while adding subtle amounts of oxygen. The loss -- the angel’s share -- can range from 5% of the volume to as much as 20% before the wine is ready to offer to the market. On the down side, that loss in volume must be regularly made up. While the ‘micro-oxygenation’ that barrels add is beneficial, too much will often yield an oxidized wine, so winemakers routinely top up the barrels with the same (or similar) wine kept in reserve. In the case of older or large barrels, it’s principally the angel’s share at work, since these barrels contribute little in the way of oak character. Either way, the finished wine is softer, more complex and more concentrated than its younger self.