Our coopers recently worked on an out-of-the-ordinary project for Huber Orchard & Winery’s Starlight Distillery: charring American oak bourbon barrels.
The distillery is based in Starlight, Indiana—at the southern edge of the state, some 30 minutes from Louisville, Kentucky. It released its first brandy in 2004.
The Seguin Moreau cooperage in Merpins, France often produces spirits barrels, though generally in larger formats for Cognac. It was a very unusual event in Napa. Not as much, however, for Master Cooper Andy Byars.
He began his coopering career in Scotland (whiskey barrels) and came over to California for the opening of the Napa cooperage.
Byars, along with Rosendo Leon on the toasting floor, built up the fires for the barrels using smaller pieces of wood and in greater quantities than are used for wine barrels.
The barrels also differ in size. American white oak barrels for bourbon hold 53 gallons, or 200 liters. Standard wine barrels in the Bordeaux shape are 59 gallons/225L and 60 gal/228L in the Burgundy shape.
As the fires became bigger and hotter, the coopers used the toasting lid to concentrate the head and to bar all oxygen.
Byars removing the toasting lid below:
Removing the lid gave the fire oxygen, which in turn blasted the barrel, burning the wood and creating the char.
Char vs. toast? And why char? Bill Owens in the Craft of Whiskey Distilling explains char on pages 44-45 of Chapter Four:
It acts like an activated-carbon filter to adsorb sulfur compounds and it provides a passage for the spirit into the pores of the oak. In the United States a full-depth charring of barrels (i.e., 1/8 inch) used to age American straight whiskey is predicated by law. This is in spite of the fact that over-charring can actually destroy some of the flavors that are needed to develop the finish of the spirit. This is why toasting, or even a light char, may be a better route, but it is illegal in the United States to age straight whiskies, such as bourbon, in any-thing but fully-charred barrels. A medium-depth char is required just to crack the wood, and a heavier char burns up wood compounds that would only be caramelized by a low- or medium-level char.
That legal requirement is set for in the Code of Federal Regulations for the Standards of Identity for Distilled Spirits, which stipulates that bourbon must be stored in charred new oak containers.