How a father-and-son team from Spain make oak wine barrels that sell for $670 apiece

• A family-run business in Spain has been making handmade wine barrels since 1975.
• Tonelería Herfe makes about 6,000 oak barrels a year and sells them for up to $670 each.
• Their artisan techniques have earned praise from their clientele.
• View more episodes of Business Insider Today on Facebook.

Making a barrel by hand is a precise science.

And one family business in southern Spain has been perfecting the process since 1975.

Tonelería Herfe makes thousands of artisanal wooden barrels for winemakers in Spain and France, and more recently, for Scottish whisky distilleries.

The company makes around 20 to 25 barrels a day, and charges as much as $670 for one. Its process involves both machinery and handmade techniques, something CEO Antonio Hernandez prides his reputation on.

"We are a small workshop that respects the essence of the process," Hernandez said. "Some clients know that and that's why they respect the prices, and pay a bit more for the barrels. It is not the same to make 20 or 25 barrels a day as it is to make 100 barrels a day."

Read on to see how the $670 barrels get made:

The Spanish manufacturer Tonelería Herfe makes about 6,000 wooden barrels a year using a process combining handmade techniques with specialized machinery.

The barrel-makers use wood from American, French, and Central European oak trees.

Each slat of the barrel is perfectly cut using this machine …

… and fitted together using metal rings. They don't use glue out of fear it could pollute the wine.

The oak must have exactly the right amount of moisture. "No more, no less," said workshop manager Antonio Hernandez Jr. "If it's too dry, it can break during the process, and if it's too wet it will look green."

The wood is toasted over a fire to give the wine a unique oak flavor.

Tonelería Herfe makes about 20 to 25 barrels a day — far less than some of its competitors. But CEO Antonio Hernandez said his customers can tell the difference in quality.

"We are a small workshop that respects the essence of the process," Hernandez said. "Some clients know that and that's why they respect the prices, and pay a bit more for the barrels. It is not the same to make 20 or 25 barrels a day as it is to make 100 barrels a day."

The company makes around $1 to $2 million in sales a year.

The company could produce thousands of more barrels a year with its machinery alone, but Hernandez insists on giving his barrels a handmade touch.

"Even though the machinery we have gives us the capacity to produce many casks, I want to maintain the quality of the barrel," he said. "The mix of artisan work and modern machinery is the essence of our company, and I'd like to keep it that way."