This image is from the Louisville Cooperage file created by Schenley after they purchased the business in the 1940s. I find this to be a very interesting photograph. For one, it shows the latest technology of the day. The barrels are on a turntable-type device that places the barrels over gas burners to be charred. When the barrel has been charred, it is discharged to roll to the next station. It appears that this device can char four barrels at a time. What I can’t detect from the photograph is if each barrel has a separate jet of flame or if they are rotated over the flames and the barrels on the right are burning with residual flames.
Technological advances have changed the coopering industry, just as it has changed the distilling industry. Machinery such as this sped up the process allowing more barrels to be produced in a day. The use of gas burners instead of wood chip fires also sped up the process. Kelvin Cooperage still chars their barrels the old fashioned way using wood chip fires with workers placing the barrels over the fires by hand. Independent Stave uses gas jets and a mechanized system feeding the barrels into the gas jets. Independent Stave can make more barrels per day than Kelvin Cooperage because of the technology. However, there are distillers that feel the wood fires used by Kelvin create a better flavor from the barrel.
When a barrel is charred it creates two major levels of flavor. The first is the outer layer of charred wood. This char gives the whiskey tannins that color the whiskey and gives the whiskey the dry, tannic flavor. Just under the layer of char is the second layer of flavor, caramelization of the natural sugars in the wood. This gives the caramel, and other sweet notes to the whiskey. Just under this layer is the toasted wood. Toasted wood will create vanilla flavors in the whiskey. Toasting does not come from the charring process, but instead, it comes from the heat used to bend the staves into place as the barrel is raised. Some distillers ask for additional time over this heat to toast the wood deeper. In fact, the charring process will burn away some of this toasted wood, so a deeper toast helps keep the vanilla flavors in a heavily charred barrel.
One of the problems with barrels smaller than the standard 53-gallon size is the toasting process. It takes less time to heat the thinner staves and bend them into shape, so when they are deeply charred, they lose most of the toasted wood unless additional toasting has been applied to the barrel. The smaller the barrel, the more likely this will happen.
By the 1960s, Schenley had sold its cooperages. Louisville Cooperage is no longer in existence. One of the old office buildings still stands near the campus of the University of Louisville. These old images are all that exist of the industrial past of the cooperage.
Image from the archives of Michael Veach