“Angels’ share” is an endearing term which describes the loss of water and alcohol (depending on humidity) from the barrel during storage. The oak soaks up a lot of liquid when first put into service, then, while some oxygen seeps into the wine, some liquid also evaporates. The Angels’ Share can amount to 2-3 gallons of wine over time. As a result, the barrels need to be topped off occasionally.
- Cooperage - any company that makes barrels.
- Heads - the round ends of the barrels made of 1-inch thick oak. One end contains the cooperage name and toasting information.
- Stave - also 1-inch thick oak boards that run the length of the barrel. Usually 28-31 staves in a wine barrel.
- Hoops - The galvanized (zinc coated) steel bands that hold the staves together.
- Bung hole - The only hole in the barrel. It’s used to load, unload, and sample the wine.
- Bung - the “cork” that fills the bung hole. It must be food grade for wine and is usually silicone.
Barrels have a rather short working life, sometimes only 1-2 years, so they usually enter retirement in pretty good shape. When a winery decides that a barrel is no longer suitable for their uses, they find an alternative purpose for it. An informal survey of Napa vineyards revealed the following ways in which barrels are reused after their prime:
- Sold to someone like us to be re-purposed as furniture or planters
- Donated to a non-profit charity
- Sold to other breweries or vineyards to continue being used
- Broken down to use as firewood for a pizza oven
- Sent to a Scottish distillery to age scotch whiskey
All barrels need to be shipped to vineyards, which takes time, and even more time if shipped internationally. While the barrels are water-tight at the cooperage, over time the wood dries out and contracts, leaving gaps between the staves. To avoid losing a lot of wine, vineyards commonly re-hydrate the barrels with steam before putting wine in them.
Bore beetles create yet another issue. These pesky guys lay their eggs in barrel crevices. When the larvae hatch, they tunnel into the oak, eating their way completely through the 1-inch boards, causing a leak. This is easily repaired by carving a toothpick out of oak and sticking it into the hole. The toothpick swells up, thus stopping the leak. Of course, if there is wine in the barrel, the little bugs drown, hopefully after drinking their fill!
When a barrel has been used for years as a storage vessel, a crusty substance begins to form on the insides of the barrel. This is called tartrates. This can actually be refined into “cream of tartar”!
Contemporary barrels are made from white oak. However, Western European oaks and North American oaks are slightly different species of tree. Also, they are aged and processed differently. In general, the French oak wood is aged from 24 - 36 months. This aging helps to neutralize some of the coarser flavors. Many (not all) American coopers use a kiln-dry method of seasoning which is generally thought to be less refined, but much faster. A French oak tree may be 80 to 120 years old before being harvested, but only produces two barrels due to the fact that their oak must be split, yielding only 25% of the tree as usable for barrels. American oak may be serrated, making it twice as economical. The taste difference in wines aged in French oak vs. American oak are subtle, but generally those lucky souls with fine pallets declare the French oak is more subtle while the American oak is more “in your face,” as one critic described it. As one might imagine, French oak is more expensive than American oak. For example, in 2007 prices, the American barrels were selling for about $600 - $800 while the French barrels commanded around $1200 per barrel.