For centuries, European vintners used monstrous concrete tanks to ferment and store their wines, a technique used in California's oldest wineries before Prohibition.
But when the state's wine industry blossomed in the 1970s and 1980s, many wineries turned to stainless steel.
Now, concrete is making a comeback. North Coast wineries are trying an old technique in a new way, installing small, portly concrete tanks that look like creatures from another world.
In Sonoma County, it all started when Don Van Staaveren, winemaker at Three Sticks Wines, pitched the idea of making concrete wine tanks to his neighbor, Steve Rosenblatt, the president of Sonoma Cast Stone. Rosenblatt was already making unusual countertops, sinks and walls, and with a small vineyard of his own, he had an interest in winemaking.
"In the early history of winemaking, concrete tanks were very prevalent, and there were some really outstanding wines made in concrete tanks," Van Staaveren said. "So I thought, well, there's no reason why we can't do it again."
After a few years of developing a prototype together, Rosenblatt sold his first concrete egg in 2011, and he has been challenged to keep up with the pace of orders ever since. He sold about a dozen tanks in 2011, and 26 tanks this year. For 2013, he has already received orders for at least 54 tanks.
"We've got a window of opportunity, and it will last maybe 10 years," Rosenblatt said. "We're investing in it, because we see the market going this way, and we want to become the name in concrete wine tanks."
Five years ago, before Rosenblatt entered the scene, the go-to source for concrete-curious winemakers was Nomblot, a French company that has manufactured concrete wine tanks since 1922. International shipping for bulky tanks can cost thousands of dollars, so Rosenblatt saw an opportunity to fill a local need.
Winemakers in Europe have fermented their wines in concrete tanks for thousands of years. Some of the cement structures installed by early California wineries are as large as a building, spanning 20 feet by 20 feet.
But in the 1970s and &‘80s, when the California wine industry was blossoming into a powerhouse, wineries began turning to stainless steel fermentation tanks, which were easier to clean. Around Sonoma Valley, some of those blocky former concrete tanks have been transformed into shops or winery rooms, with rough-hewn doors cut into the boxy shapes.
"All the old wineries used to have cement cooperage and redwood tanks. That was the name of the game in the old days," said Jon Fredrikson, president of Gomberg, Fredrikson & Associates, a Woodside wine industry consulting firm. "I guess the old guys knew something that has now been rediscovered.
"It's the ultimate irony when you think of how many millions of gallons of cement cooperage were ripped out of wineries," Fredrikson continued. "They're definitely making a comeback."
The concrete tanks made today are different from the previous generation. They're generally smaller, and the tanks made by Sonoma Cast Stone are porous, allowing tiny amounts of oxygen to gradually seep into the tank during fermentation. Because the egg-shaped tanks are smaller at the top, the oxygen bubbles that rise during fermentation are pressured to move more quickly. That creates a liquid current within the tank, so the wine is constantly moving.
"When you look in it when it's fermenting, you can see it moving, like it's an ocean," Rosenblatt said. "The wine loves to touch the concrete for two reasons. One is the air exchange, the other is it picks up a minerality."
Thomas George Estates in Healdsburg was among the first wineries to try one of Rosenblatt's egg-shaped concrete tanks. Winemaker Chris Russi had encountered the concrete eggs when he worked in Australia, but they were coated with an epoxy, so they couldn't "breathe," he said.
"It's like a barrel in that it breathes, but it's not going to have an oak influence into the wine," Russi said.
The bulbous tanks also have been a hit with visitors.
"Whenever somebody sees it, they just need to put their hands on it," Russi said. "It's like the egg ship from &‘Mork and Mindy.'"
Inside the walls of Rosenblatt's concrete eggs are optional glycol tubes that vintners can use to control the temperature.
"We really like the character," Van Staaveren said. "I think the biggest contribution of the egg-shaped fermenter for white wines is textural. The fermentation dynamics are really nice, also, because it's slow to warm up and slow to cool down, so you have a nice, long, controlled, cool fermentation."
The current that builds up inside the egg keeps the sediment, or "lees," in suspension, instead of settling on the bottom of the tank, changing the wine's texture, he said.
"It's just a richness on the palate. A little bit of creaminess to the wines," Van Staaveren said. "They just taste fuller on the palate. A little smoother or well-rounded."
But the technique doesn't work for everyone, and opinions differ on how fermenting in concrete impacts the flavor.
Flowers Vineyard & Winery in Cazadero tried fermenting its Sonoma Coast chardonnay in egg-shaped cement tanks for several vintages, but didn't like the results.
"Every year, the chardonnay made in the concrete egg just seemed to be tired," said Jason Jardine of Flowers Vineyard & Winery. "It didn't really have the focus and clarity as the one made in stainless, and in the barrel. It didn't really create the development of aromatics for texture. ... It just seemed muddy, from all the continual movement in the lees."
Others have stuck with stainless steel because it's easier to clean.
The 500-gallon concrete egg-shaped tank made by Sonoma Cast Stone costs $7,700 for the basic model, according to the company's brochure. Prices for larger, rectangular concrete tanks can cost up to $30,000, Rosenblatt said. By comparison, Quality Stainless Tanks, based in Windsor, sells custom-made 500-gallon stainless steel fermentation tanks for $5,800 to $7,000, "depending on the bells and whistles," said Scott Dapelo, sales manager.
Rosenblatt, 78, acknowledges the concrete egg-shaped tank could lose favor just as quickly as it gained popularity. In the meantime, he's developing new prototypes to capitalize on the trend, including stackable concrete wine tanks that look like treasure chests.
"Something else will come along, but it will be a long time before it does, because it's an inherently good product," Rosenblatt said. "It's either going to meet with huge success, or people are going to say, &‘What, are you crazy?'"