A basic definition of bourbon is that is has to contain at least 51% corn and be aged in new oak barrels charred on the inside. There are other criteria, too, but these are the two basics requirements.
As part of the Bourbon Classic in Louisville, a bunch of other journalists and I were invited for tours of distilleries like Jim Beam and Buffalo Trace. Visiting those places was cool, but almost more fascinating were tours of the cooperage that made the barrels and the metal works that created the stills used in the making of bourbon.
"The barrel is an ingredient," said our guide at Brown-Foreman, a mammoth and diversified company that owns brands like Jack Daniels (which is not bourbon, by choice) and Old Forester (the oldest bottled bourbon).
Because new oak is required for bourbon, it takes a lot of trees to make a year's worth of bourbon barrels. This year has been a problem: because the spring was so wet, the trees couldn't be harvested and the barrels could not be made. That is a constraint on production of bourbon…but we won't have to worry about that for a while (straight bourbon has to be aged a minimum of two years – four if it's "bottled in bond").
Making bourbon barrels is still very much a hands-on activity, and none of the barrels are assembled using nails or glue, which could contaminate the contents. Guys still array the staves in copper rings as they have done for centuries. The only process that we saw that was almost entirely automated was the most dangerous step, where a low-mounted flame-thrower chars the inside of the barrels before they're filled. It's this charring that helps gives aged bourbon its color: when it comes out of the distillation process, it's "white dog," colorless; after a while in the barrel, it acquires from the wood the dark brown-to-reddish color that is so closely identified with bourbon, as well as notes of vanilla, caramel and tobacco. Like the man said, the barrel is an ingredient.
Every distillery we visited around Louisville had equipment bearing the Vendome nameplate. Vendome Copper & Brass Works has been turning out stills and related equipment for the local bourbon industry for over a century.
Copper is the preferred metal for stills because copper is very easy to work with, it's highly malleable, and it reacts with and binds sulfites that remain on the copper after the liquid is removed.
Like the construction of the barrels, making copper stills is very much a hand-crafted operation that requires time-honed skills. There's welding equipment and power tools that might not have been available to metal workers in years past, but these products from Vendome, like many things related to bourbon, are made in the old ways.
Vendome Copper & Brass Works has been owned by the same family for over a century, and tradition is important in this part of the country.