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Winemakers Turn to Egg-Shaped Tanks

Eggs in a line. Credit: Sonoma Cast Stone

Eggs in a line. Credit: Sonoma Cast Stone

Like most wine writers, I’ve toured dozens of wineries, and seen the insides of more fermentation cellars than I care to recall. Vintners just love to show off their shiny stainless steel tanks, despite the fact that theirs look exactly like the ones at every other winery on the planet.

“You mean you have tanks?” they imagine us asking. “Well don’t just stand there, man, show them to me!”

Just when I thought I’d seen every variation of fermentation tank known to winemaking, I came across something truly different: the concrete egg. Made of the same material as the average driveway and shaped like a giant chicken egg, the concrete egg began appearing in the cellars of West Coast wineries in 2003, and it seems to be hatching a legitimate winemaking trend.

Because concrete is porous, the tanks are said to be “breathable,” like barrels, but without adding any oak character to the wine. The egg shape plays a role, too, by helping to create a natural stirring effect during fermentation. And, some say, by channeling the celestial energy of the universe.

Today, concrete eggs are being used by such respected wineries as Quintessa, Harlan Estate, Screaming Eagle, Viader and many others.

A concrete history

eggs at Quintessa

Concrete eggs at Quintessa. Credit: Tina Caputo

While egg-shaped tanks are a new invention, concrete tanks have been used in winemaking for centuries. Giant rectangular concrete vats were commonly used by large California wineries until a couple decades ago, when they fell out of fashion in favor of stainless steel.

But concrete vats continued to be used by wineries in Europe, including some of the great chateaux of Burgundy and Bordeaux. This caught the attention of Charles Thomas in the early 2000s, when he was the winemaker at Rudd Oakville Estate in the Napa Valley.

Thinking there must be something to this concrete thing, Thomas, now the head of winemaking at Quintessa in Napa Valley, went to see Marc Nomblot, whose family makes concrete wine vats in Burgundy. Nomblot told him that the egg-shaped tank was originally designed for French winemaker Michel Chapoutier, who, as a follower of the sometimes-mystical biodynamic approach to agriculture, believed there was special power in the egg shape.

“An upright egg is supposed to concentrate the energy vortex of the celestial energy,” Thomas said. “But it had already turned my head before Marc told me anything about the biodynamic philosophy.”

Thomas brought two eggs back to California in 2003. “These were probably the first new concrete tanks in Napa Valley in at least 40 years,” he said.

And so began a trend.

Physics or magic of egg-shaped tanks?

Once Thomas was able to test-drive his eggs, he discovered some unexpected benefits.

“My rationalization was that maybe I’d get the richness of a barrel fermentation without the oak character, and I did,” he said. “But what I didn’t count on was a greater level of complexity beyond what you would have seen in a stainless steel vessel.”

When Thomas moved to Quintessa in 2008, he began using concrete eggs for the winery’s Illumination Sauvignon Blanc. Now the winery has 13 of them.

Charles Thomas

Charles Thomas, an early fan of the eggs. Credit: Tina Caputo

“Stainless steel has a brightness and a purity of aroma and fruit,” he said. “Concrete also has purity of fruit, but with more complexity aromatically. In the mouthfeel, stainless steel is a bit leaner and tighter, and the concrete is going to have a little bit rounder, richer mouthfeel in the wine.”

Although some claim that the convection from fermentation inside the egg creates a vortex that continually mixes the lees, leading to better mouthfeel in the wine, Thomas isn’t completely convinced. “There are a lot of ‘true believers’ out there that go further with this than I would in terms of claims,” he said.

Anna Matzinger, winemaker at Archery Summit in Oregon’s Willamette Valley, takes a more lighthearted attitude toward the alleged powers of the concrete egg. She has used one to make Archery Summit’s Ab Ovo (“from the egg,” in Latin) Pinot Gris since 2008.

“What the egg offers is this really interesting textural depth, and then you still get the precision of what you might get in stainless steel fermentation,” Matzinger said.

And a little magic can’t hurt, either.

“Those who follow biodynamics think (the vortex theory) is a terrific idea,” she said, “because a vortex is connecting the energies of the cosmos to the energies of the earth.”

Does she actually believe that stuff about the cosmos?

“Any time you can talk about the universe conspiring to help you do something better, why not just go with it?” she said. “I say that in jest a little bit, but I also think it’s kind of interesting. If you stood over any stainless steel tank of white wine fermenting, it’s kind of moving around in a circle. Whether it’s doing that differently in the egg because of the rounded bottom, and if it’s more connected with the cosmos because of that, I’m not quite sure. But I still think there’s something magical about the egg.”

Seeing red

Although concrete eggs are used primarily for white wines, they can also be used for reds.

Viader Vineyards & Winery in Napa Valley has used concrete eggs for a variety of wines since 2004. “I find it ideal for our Petit Verdot,” director of operations Alan Viader said. The egg-fermented wine is part of the blend for Viader’s V, which sells for $150 per bottle.

The egg contributes to the mouthfeel and weight of the wine, Viader said, while preserving fruit character and delicate aromatics. “Wines are usually better quality than the exact same lot of wine fermented in our square concrete tanks,” he said. “If I had the space I’d love to have dozens of eggs in all different sizes.”

At nearly double the price of an equivalent-capacity stainless steel tank, that could get expensive. But even so, interest in the eggs continues to grow, according to Steve Rosenblatt of Sonoma Cast Stone in Northern California.

“We began by selling exactly a dozen eggs the first year,” said Rosenblatt, whose company began producing them in 2010. Last year, he sold more than double that number.

Although that doesn’t exactly constitute widespread adoption, Rosenblatt predicts that more wineries will try the eggs as word gets around. “With any trend there are always the leaders and the followers.”

And the leaders tend to give much more interesting cellar tours.

Eggs in a row. Credit: Sonoma Cast Stone

Zester Daily contributor Tina Caputo is a wine, food and lifestyle writer based in Northern California. Her stories have also appeared in the San Francisco Chronicle, Wine Review Online, and Sonoma magazine. 

  • Arnold Waldstein 1·22·13

    Thanks for the post.

    One correction…egg shaped vessels for both fermenting and storing wine have been around for at least 8,000 years starting in the Republic of Georgia with Kviri.

    A good post covering that is here:

  • Tina Caputo 1·22·13

    True, Kviri vessels are rather egg-shaped! Interesting article, thanks for sharing.

  • marco cecchini 1·22·13

    one question.. on the inside surface are the ” eggs” covered with something ???

  • Tina Caputo 1·22·13

    There’s no interior lining — they want the wine to come into direct contact with the concrete.

  • Julian Scholefield 1·22·13

    Great post, the tanks in the above photo with the embezzled “O” are located at Okanagan Crush Pad Winery, located in Summerland, British Columbia, Canada. They were delivered to us from Sonoma Cast Stone and were the first egg-shaped concrete fermentation tanks in Canada. We have used them to great success for the last two years and are hoping to purchase more concrete tanks in the near future. For more info on our wines visit, Cheers!

  • Tina Caputo 1·22·13

    So cool, and what a great display. Would love to see your operation sometime.

  • JD 7·15·13

    How long does the wine (red and white) stay in the tank and how much does a tank cost; say 5, 10 or 20K?

  • Tina 7·17·13

    Hi JD,

    I’ve asked Steve at Sonoma Cast Stone to answer that one for you. Stay tuned…

  • Steve Rosenblatt 7·17·13

    JD – We now have 6 styles and sizes of concrete wine tanks. They range in size from 200 gallons to 2200 gallons. The costs also range from $6500 to $32,000. The popular egg discussed in this article begins at $10,500 and averages around $14,000 with all options specified.

    The fermentation ranges from about 2 weeks to a few months, depending on the type of wine and the winemaker desire. If you have a specific wine in mind, let me know and we can get you a more specific answer. To learn much more about using concrete take a look at

    Thanks, Steve

  • PETE MCHENRY 4·11·14

    good article with helpful information, I hang out in NZ and may have a go at concrete eggs for
    our winery

  • Tina 4·12·14

    Thanks, Pete, I hope it goes well for you!