Immediately’s coopers use fashionable instruments to craft bourbon barrels, however the course of hasn’t modified a lot via the years. Every barrel is assembled by hand over the span of about two hours, and held collectively utilizing fastidiously utilized stress and exact geometry—all with out nails, glue, or different adhesives. Right here’s a take a look at the way it all occurs.
The Start of A Bourbon Barrel
1. Gathering the Wooden
American white oak is probably the most generally used barrel wooden, resulting from its superior water retention. The timber are sometimes felled when 80–100 years previous and 70 to 100 ft tall, and a mean of 1 to 2 barrels might be produced from every tree. Logs are minimize into three-foot sections (roughly the peak of 53-gallon barrels), then sawn into 4 quarters and minimize into tough staves. The staves are stacked onto pallets and left outdoors to air dry for a mean of three to 6 months. Some distillers request longer seasoning intervals of as much as 36 months.
2. Form It Up
Coopers run the seasoned staves via equipment to trim them to a size of round 35 inches. Brown-Forman Cooperage in Louisville has a very superior setup that automates the whole course of. However as a result of they’re quarter-sawn the staves don’t all have the identical width, which makes meeting like fixing a jigsaw puzzle. Coopers begin by including staves one after the other, inserting them right into a metallic ring used as a brief base, choosing ones that can match collectively exactly. As soon as the match is tight (it often takes 25–32 staves), a second ring is positioned across the prime to carry issues in place for the following step.
3. Steaming Into Form
The staves are then despatched via a steam tunnel which heats them to round 120°F to allow them to be bent into the barrel form, often utilizing an overhead inverted cone that presses down on the staves and replaces the ring with a brief hoop that matches extra tightly. Coopers add extra of those “building rings” till the ultimate hoops are added later. After including these rings, coopers set the form by heating the barrels once more.
4. Toasting and Charring Time
Now the barrels are able to be toasted and/ or charred, which could have a serious affect on the flavors drawn out of the barrel. Gasoline ovens, wooden fires, or electrical tubes produce temperatures between 250° and 550°, toasting the barrel for 9 to 40 minutes. Length and temperature are as much as the distiller, and a few skip toasting completely. Subsequent comes charring, which is required by legislation. Gasoline-fed fires burn the within of the barrel, making a layer of carbon and breaking down compounds like lignin, tannins, and cellulose that contribute key flavors. The char ranges are numbered 1 to 4: No. 1 (as much as 15 seconds), No. 2 (20–30 seconds), No. 3 (30–35 seconds), or No. 4 (as much as 60 seconds.)
5. Put a Head on It
After charring, coopers minimize notches across the inside fringe of the staves at each ends of the barrel. This “V” or “U” formed minimize is named the croze, and it’s the place the barrel heads relaxation. As soon as every head is popped in, coopers take away the short-term building rings, changing them with “head hoops”—the primary two of the six hoops to be utilized. The heads are pressed down and the hoops are tightened, which clamps the croze down on the heads, creating a good seal earlier than being riveted in place.
6. Ship within the Hooper
Setting the heads within the earlier step required stress, which may warmth the barrels up once more. To stop the wooden from turning into pliable and doubtlessly deforming, coopers let the barrels cool off for a couple of minutes earlier than the hoopers add the remaining 4 hoops. The innermost two hoops are referred to as the bilge or stomach hoops, whereas the quarter hoops sit between these and the pinnacle hoops. These 4 hoops are additionally riveted, closing the joints in the midst of the barrel. As soon as the hoops are in place, coopers drill the bunghole— a gap in a single stave on the middle of the barrel’s physique—via which liquid might be added or eliminated. The bunghole will probably be plugged with a chunk of wooden referred to as a bung, which is sort of a stopper or cork. Now the barrel is actually full.
7. Strain Testing the Completed Barrel
Subsequent, the coopers put the barrel to a closing stress take a look at. A couple of gallon or two of water is added to the barrel together with 5 to 9 kilos per sq. inch of air stress. The thought is to make use of that stress to detect any latent defects within the wooden—like wormholes, knots, or mineral streaks—which may result in leaks. Smaller defects might be plugged with cedar wedges. A defective stave might require the barrel to be disassembled and the stave changed—a course of coopers often can accomplish shortly. The brand new staves should be minimize precisely to duplicate those they substitute, from the size and width to the depth and exact location of the croze cuts, to make sure the match will probably be good. As soon as a barrel passes the take a look at, it’s despatched off to a distillery the place it’s prepared to simply accept whiskey.
