You see them when you tour older wineries in poorer parts of Spain or Portugal–big cement fermentation tanks, squarish in proportion and often open-topped or covered with a slab of metal. To those of us accustomed to polished stainless steel fermenters, they seem a throwback to the dark ages of winemaking, days when barber-surgeons operated on people with rusty tools and wines still had that elusive sense of place that can only be imbued by distinctly local bacteria and blissful ignorance of the niceties of microbiology and organic chemistry.
Many of the old-school concrete fermenters that are still in use in the United States and abroad have long since been coated in wax or some sort of inert material to keep the wine from direct contact with the concrete, often for reasons known precisely only to the ancestors of the previous winemaker.
In the U.S., those old concrete tanks are seldom seen on winery tours, and when they are, the official line is generally, “They’re being phased out.” But in similarly tech-savvy Australian wineries, concrete tanks are still the preferred fermentation vessel for production of many of the nation’s classic wines: Hardy’s Eileen Hardy Shiraz, Tyrell’s Vat 9 Shiraz and Torbreck RunRig Shiraz, to name but a few. Penfolds stopped using them for Grange in 1973, but the lined concrete fermenters at Penfolds’ Magill Winery are still used for other wines.
By some reports, square, open-top concrete fermenters are still widely used in Burgundy. While they aren’t necessarily fashionable throughout Bordeaux, Christian Moueix and his head winemaker Jean-Claude Berrouet exclusively employ modern concrete fermenters coated with an interior layer of cement to make Chateau Petrus, Chateau Lafleur-Petrus and Chateau Trotanoy in Pomerol.
For Moueix, concrete is more than just a sturdy alternative to stainless steel and oak foudres–it’s the material of choice. Does concrete have unique properties that oak and stainless steel lack? Some obviously believe that it does, and their success has piqued the curiosity of some American winemakers. Viader and Rudd Estate are two top-shelf Napa wineries that are taking a hard look at concrete fermenters.
Cement Versus Concrete
Cement and concrete are terms which are often used interchangeably, but the two materials aren’t identical.
Cement is generally composed of limestone, calcium, silicon, iron and aluminum, plus other trace materials. It is cooked in kilns to form marble-like “clinkers,” then ground into a powdery sand, to which gypsum is added. Mix it with a little water and allow it to set, and you have nice hard cement.
Concrete is made from crushed stone, rock and sand held together by cement. The cement is only about 15% of the total mass of concrete. Concrete is stronger and less porous than cement alone.
Advantages Of Concrete Fermenters
Advocates of concrete fermenters generally cite concrete’s ability to maintain a steady temperature during fermentation as one if its chief benefits. Even wax- or steel-coated concrete tanks share that temperature-stabilizing quality.
At the Bear Creek Winery facility in Lodi, Calif., where Ironstone and Leaping Horse wines are made, winemaker Craig Rous likes to use the 24,000 gallon epoxy-lined, closed-top fermenters, supplemented with oak staves, to produce his Chardonnay.
“They’re efficient, and not everyone ferments on oak. It gives you more integration into the wine … it softens the wine and adds butter and toffee character,” Rous says.
Christian Moueix also praises the temperature stability of concrete fermenters, and believes that they produce clean-tasting wines. “The fermenters maintain a stable temperature throughout fermentation, which is very beneficial during the end part of maceration,” says Moueix, whose fermenters range in size from 1,500 to 3,000 liters.
“You have a very clean wine and you do not get the residual musty essence from the barrels or cellar,” says Moueix, who also believes that concrete helps to combat reduction. “The disadvantage is that it is very hard to keep it sanitary.”
Like wood, concrete is also to some degree permeable. Does that give concrete a micro-oxygenative effect that helps to add texture? “It’s definitely permeable, which makes it very similar to wood–micro-ox is the new word for it,” says Charles Thomas, winemaker at Napa Valley’s Rudd Estate. “Don’t be surprised if, after you put the first wine in there, the level goes down six inches.”
Rudd Estate and Viader are two notable Napa Valley wineries that have been experimenting with concrete fermenters for the last couple of years. In fact, they split the cost of shipping a container of fermenters from a producer named Nomblot in Burgundy (cuves-a-vin.com). According to Rudd Estate’s Thomas, Nomblot was best known for producing concrete mausoleums before it began producing concrete fermenters in quirky sizes and shapes.
Thomas currently has one pyramid-shaped open top 1,050-gallon fermenter. Delia Viader has several 600-gallon egg-shaped fermenters, but says she may move to slightly larger ones with the same shape.
by Tim Teichgraeber