HOW WINE BARRELS ARE MADE : A WINEMAKER'S INSIDE LOOK AT A FRENCH COOPERAGE

Oregon winemaker Brianne Day of Day Wines shares her unique insights from working as a barrel sales representative in Bordeaux, where she learned firsthand how wine barrels are made.

Most wine lovers understand that oak barrels influence their favorite wines, but few grasp the extraordinary craftsmanship behind each barrel. During my conversations with Brianne Day, founder of Day Wines in Oregon's Willamette Valley, she shared her rare perspective on cooperage—gained while working as a barrel sales representative in Bordeaux.

Her firsthand account of French barrel production reveals a craft that combines forest management, precision engineering, and artisanal skill spanning generations.

Brianne Day knows her stuff when it comes to oak barrels. Photo: Bowler Wine, NY

From French Forests: The Foundation of Every Barrel

The story begins in carefully managed French forests, where oak trees destined for wine barrels grow under conditions designed for quality. As Brianne explained to me, the process starts at the Cité de Brantôme forests, where nature and human planning intersect.

"The forests themselves are planted by natural means—the acorns that drop from the oaks replant themselves, and the forest is regenerated that way," she observed during her time there. But the human element is crucial in tree selection.

The harvesting strategy fascinated her: "When the coopers come through to source the wood, they choose the trees and then they're optioned off to each cooperage. They harvest one time, then come back through many years later and harvest the second time, then come back through many years later and harvest the third time."

This rotation system serves a specific purpose. "They want there to be a lot of density of wood in the forest because it encourages the trees to grow tall and straight with not a lot of branches," Brianne explained. Since only wood below the branch line can be used for barrels, forest density directly impacts barrel quality.

The economics are stark. From any given tree, "you can only use about 20% of the wood that's on the trunk. So if you have 5 cubic meters of trunk, you get one cubic meter of staves." The rest? "You can't use the outside of the tree at all because it's too sappy and wet, and you can't use the heartwood because it's too old and brittle. You can only use the sweet spot in between."

How are wine barrels made? {Part 1 of 4) - From Ask A Winemaker

Precision Engineering: Converting Logs to Staves

Watching the sawmill operation gave Brianne deep appreciation for the engineering precision involved. The usable portions of trunks travel on conveyor systems to hydraulic splitters that generate six tons of force.

"It just cuts through the logs like a knife through butter," she recalled, but the cutting technique is critical for barrel integrity. "They're cut with the grain so that the wine doesn't have any channels to leak out of the barrel."

The dimensional planning impressed her as much as the raw power. Staves are cut to specific thicknesses—"typically 27mm and 22mm, depending on if they're thin stave or regular staves"—but here's where experience meets science.

"They cut them about 5mm thicker than that because the wood itself holds 85% humidity when it's first cut, and after it goes through the seasoning process it has less than 20% humidity, so they have to account for that shrinkage."

The variation in stave widths, created by cutting round trunks into pie-shaped sections, isn't a manufacturing defect—it's intentional engineering. "Each stave is going to have a different width, which later adds to the overall strength of the barrel because you have all these different widths of staves," Brianne explained. "If you had all wide staves, you'd put a lot of stress on the boards and it could cause cracking. If you had all narrow staves, you're increasing the amount of points where they come together where there could be leakage."

How are wine barrels made? {Part 2 of 4)

The Patience of Perfection: Outdoor Seasoning

What struck Brianne most about cooperage was the commitment to time. Staves spend years in outdoor seasoning yards, "exposed to the natural elements for anywhere from 2 years up—I saw some that had been seasoning for 4 or 5 years, but normal is 2 or 3 years."

During this extended seasoning, "the wood is exposed to rain and wind and drying out, and it loses a lot of mass." A 27mm stave shrinks to about 22mm. The visual evidence of this transformation impressed her: "All around the bottom of the pallets of staves, it looks like the color of black tea because all the tannins are coming out and staining the ground."

Artisanal Assembly: Every Barrel a Custom Creation

After years of seasoning, the real artistry begins. Brianne discovered that each barrel requires a completely custom selection of staves.

"Since all the staves have slightly different widths, each barrel has a unique set of staves that goes into it," she explained. "You have a person who selects the staves to make up the exact width of a barrel—he has a tabletop that's the exact width of a regular barrel and he finds the staves, puts them in until they fit perfectly to make the width of a barrel. It's like he's building a little puzzle for each barrel."

The selected staves are arranged into what coopers call a "rose"—staves placed upright in a working hoop to create what looks like "a big open, one-sided barrel." The cooper then "rearranges the staves until they fit really tight and then knocks them into place."

How are wine barrels made? {Part 2 of 4)

Fire and Artistry: The Art of Barrel Building

The most dramatic part of the process involves fire. "Essentially all barrels are fire-bent," Brianne told me, though some undergo steam or water treatment first to reduce astringency from the wood.

The fire-bending process combines ancient technique with mechanical assistance. The open-sided barrel is positioned over fire with "a metal coil around it that pulls tension in opposite directions. As the fire is toasting in the middle of the barrel, a winch rolls in some of the metal coil and pulls it in opposite directions to make the splayed-out staves come together into the barrel shape."

What amazed her most was the human element in this high-stakes process. "They don't have any way of monitoring it as far as temperature gauges or anything like that. They build the fires and there's one guy whose job it is to monitor the toasting of the barrels. He moves them around and flips them around so that they're getting even toasting all throughout, but it's completely human-controlled."

From Function to Beauty: Finishing and Quality Control

Barrel heads are crafted from "pieces of staves that are too short to be used for barrels," assembled with double-sided nails that act "like dowels that go into both sides of the stave." Natural reed provides gasket material "because it minimizes channels for wine to leak out of the barrel and acts like a gasket in between places that would be more prone to drying out."

Quality control impressed Brianne with its thoroughness. "When the barrel has been finished, they test it by putting a small amount of water in it and enough air pressure to mimic a full barrel of wine, then they put it on a machine that rolls it around to see where there might be any leaks in the barrel. If there is a leak, it will shoot out air and water, and the cooper can see where that leak is and fix the problem before it goes to the final stage."

The finishing process includes precision sanding and laser engraving. "It puts on the company's logo, and if the winery also has a logo or branding that they want on it, we can put that information on it as well—the toast level, the company, and the winery's brand."

How wine barrels are made (Part 4 of 4)

A Global Craft with Zero Waste

The finished barrels travel worldwide. During Brianne's December visit to the cooperage, "the barrels that were being made and shipped out were mostly all for the southern hemisphere—Australia, New Zealand, Argentina, Israel, China, India."

Nothing goes to waste in this process. The cooperage "also owns a railroad tie company and a pallet company, so anything that they can't use" for barrels serves other purposes, completing a cycle of utilization that spans from forest floor to finished product.

Why Understanding Cooperage Matters

Brianne's insight into barrel production has influenced her winemaking at Day Wines, where she uses neutral French oak barrels for aging wines like her split-fermented Vin de Days Rouge. "When I choose neutral French oak for aging our wines, I'm not just buying a container—I'm investing in centuries of craftsmanship, forest management, and artisanal skill," she reflected.

Her experience reveals that every barrel represents years of forest planning, patient seasoning, and individual craftsmanship. Understanding this process helps explain why premium cooperage commands respect among serious winemakers—and why the flavors that develop during barrel aging carry the signature of ancient craft traditions.

The next time you taste a wine aged in French oak, remember Brianne's words: that flavor came from "forests managed across generations, staves seasoned through multiple seasons, and coopers who still bend barrels over open flames, guided only by experience and intuition."

Brianne Day founded Day Wines in 2012 in Oregon's Willamette Valley, where she produces natural wines from biodynamic and organic vineyard sources. Her wines are available in Illinois at Candid Wines. Since her first vintage, we have been proud to be Brianne's first distributor outside of Oregon!