Clay vessels have been used to ferment and age wine since ancient times. Iron Age wine vessels recently found in the Republic of Georgia were tested and confirmed to be the world’s oldest. “Almost every ancient culture, from the Canaanites to the Egyptians to the Assyrians to the Greeks and Romans, vinified in pottery vessels,” says Patrick McGovern, Ph. D., the scientific director of the Biomolecular Archaeology Laboratory at the University of Pennsylvania Museum in Philadelphia. His team conducted the liquid chromatography-mass spectrometry testing that confirmed the age of the Georgian vessels.
While these pots are an uncontested link to the past, they are also becoming a resource for the future of winemaking. Beyond the romanticism involved in borrowing ancient techniques, terra-cotta pots offer unique interactive properties with wine—they pull out acidity, allow oxygen exchange, and provide superior insulation, among other benefits—that are different from those of stainless steel, wood barrels, or concrete. These factors are are capturing the attention of winemakers around the world and encouraging new scholarship.
There are several types of clay vessels in use today, including the amphora, the tinaja, and dolium. “One real issue that we are running into is the nomenclature of these vessels,” says potter-turned-winemaker Andrew Beckham of Beckham Estate Vineyard in Oregon’s Chehalem Mountain AVA. An amphora, which many people use as a catchall term for any clay vessel, actually refers to a specific vessel shape. “An amphora would be skinny, with a completely conical bottom,” Beckham says, “and have hooked handles at the shoulders. It would be used for transporting wine on ships.” Amphorae would be small, stackable, and stored under ships’ decks.
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More common, and less noted, are tinajas and dolia. A tinaja is a Spanish clay vessel that tapers at the top and the bottom, like an egg, and is large enough to ferment in. A dolium is similar to Georgian qvevri (but is made outside Georgia and isn’t quite as big) and has a tapered but flat bottom. It stands out in comparison to the others for its wide-open top. Dolia are ideal for red-wine fermentations or skin-contact whites, as the larger opening at the top makes the removal of must from the juice far easier.
Georgia’s Clay Winemaking Legacy
Georgia’s Kakheti Valley abuts the southern slopes of the Caucasus Mountains. Here, the winemaking style is defined by the use of extended skin macerations—especially for white grapes—creating what locals call amber wine. A vital aspect of the historic recipe is the fermentation and aging of these wines in qvevri (pronounced kway-vree): huge earthenware, inverse teardrop–shaped vessels. Like tea leaves being steeped, the grape juice and must are macerated in the subterranean qvevri for six months. The resulting wine has a deep, whiskey-like amber color that is unmistakable in the glass. The extended skin-contact of endemic Rkatsiteli or Kisi grapes yields the wines’ unique flavor spectrum, from floral, marigold honey to tannic, peach notes of raw pu’er tea.
As the winemaker for Vinoterra, in eastern Georgia’s Kakheti, Gogi Dakishvili is an unmatched expert in the use of qvevri. With 98 of the vessels, holding up to 2,000 liters apiece, Vinoterra is the largest qvevri operation in the country. At such a scale, the physical effort required is extraordinary. “It takes eight men per season running qvevri production to make around 150,000 bottles,” says Dakishvili. In comparison, “those same eight workers would be able to make 10 times that much wine using conventional Western technology.”
What makes qvevri vessels unique? The locally mined Kakhetian clay has a limestone base and is speckled with trace minerals. Also, “the qvevri are fired at around 1,832°F [1,000°C],” explains Dakishvili. “If you go above 2,192°F [1,200°C], the pots become ceramic and are too fragile.” With only two commercial producers of qvevri in Georgia—one in western Imeriti and the other in eastern Kakheti—obtaining one of these handmade vessels is a lengthy proposition. “If you order one today, you will get it next year, maybe,” Dakishvili says. However, with the opening of the Qvevri Academy in Ikalto, Kakheti, the timeline is likely to shrink as more artisans are educated in making Georgia’s signature vessels.
Qvevri are flavor neutral, with a favorable oxygen exchange similar to that of concrete. To clean them, Dakishvili resorts to an ancient remedy of limestone ash mixed with water. This is because hot water under pressure could cause the qvevri to crack. While Dakishvili notes that cleaning is the most important activity, he says that what sets qvevri apart in winemaking “is that [they are] a natural cooling system.” With walls that are around 1.5 inches [4 cm] thick, the qvevri naturally shed heat during fermentation.
After fermentation, the must temperature falls and creates a vacuum in the qvevri, submerging the pomace cap and sealing the stone qvevri lid. Because the vessels’ interiors are lined with beeswax before they’re buried—a technique that reduces oxygen transfer through the qvevri walls—only small amounts of oxygen penetrate from the stone lid. “From this,” says Dakishvili, “we get riper and more polymerized tannins, which improves the taste of our wine.”
The Reemergence of Italian Amphorae
Archaeological records show that winemakers throughout the Italian Peninsula and Sicily transported wine in clay amphorae—small terracotta jars with handles just above the shoulders—as far back as the Copper Age. It’s possible that winemakers of the time fermented and aged wine in these vessels too. This historical context was on the mind of Giusto Occhipinti, the coproprietor of Azienda Agricola COS in Vittoria, Sicily, when he started using clay vessels in 2000. “We work with 150 amphorae of approximately 400 liters [each],” he says, “so what we are doing are 150 micro fermentations.” While the vessels he uses are far larger than those used in Roman times, Occhipinti still employs the more familiar term amphora. The labor-intensive regimen forces him to keep a close eye on the nuances of each individual fermentation ecosystem.
Using clay amphorae buried in Sicilian earth, COS produces two wines for its Pithos series: Bianco, made from 100 percent Grecanico, and Rosso, from 60 percent Nero d’Avola and 40 percent Frappato. The juices are skin fermented, then aged for seven months, all in clay. To Occhipinti, the resulting cuvées highlight the grape varieties and their terroir, allowing drinkers to “better appreciate the aspects of the vineyard.”
In Northern Italy, Elisabetta Foradori, the doyenne of Trentino viticulture, shares that sentiment. She began using clay at her Trentino winery, Azienda Agricola Foradori, in 2008. “There is a direct transfer of the message of the terroir from the grape to the wine,” she says, “with an incredible purity and energy.”
Foradori cites control and cleanliness as important factors in her winemaking style, and she keeps her unlined clay vessels aboveground to maximize these aspects. The vessels allow for a long skin contact of seven to nine months, she says, which gives her a practical advantage: “We don’t use sulfites because of the protection from the grape skins.” Foradori is now using clay vessels to ferment and age four of her seven wines: Fontanasanta Nosiola, Fuoripista Pinot Grigio, Teroldego Morei, and Teroldego Sgarzon.
Both Occhipinti and Foradori work with Juan Padilla, a fifth-generation craftsman of clay vessels from Villarrobledo, Albacete, Spain. Padilla uses three types of clay to construct the pots; after firing, he matures them for two years before they’re used.
While Occhipinti is happy with the results, he sounds a warning for winemakers looking for shortcuts to improve their wines. “The amphora,” he says, “is not a magic box that will change the grapes and turn banality into complexity or into a great wine.”
New World Clay Experiments
While historic wine regions are showing renewed interest in making wine in clay vessels, New World winemakers have also launched experiments. Beckham, of Oregon’s Beckham Estate Vineyard, came to winemaking after 17 years as a ceramicist, and he’s experimented extensively with clay vessels. He makes two historically referenced shapes, the dolium and the tinaja, which range in size from around 151 liters to about 757 liters. All his pots are unlined and are able to hold wine without any beeswax.
Like Dakishvili, Beckham calls out the temperature-regulating properties of clay as one of its primary benefits. “Two tons of grapes will ferment for 30 to 35 days with peak temperatures around 20° to 22°C [68° to 71.6°F] in clay,” Beckham says. “While the same two tons of grapes in non-temperature-controlled wood or steel will finish fermenting in 10 or 11 days. The temperatures will max out around 30°C [86°F]!” The lower temperatures for clay-fermented wines create brighter and fresher wines.
Regarding shape specifically, there are advantages to using dolium versus tinajas, as well as varying usage between the two. The wide-top opening in dolia makes these a preferable vessel for primary fermentations of red wine and skin-contact white, as it allows the pomace cap to rise and the must to be strained from the juice. For any pressed wine, Beckham uses the more tapered tinaja. “Because of the [their] shape and kinetic quality, [tinajas] work like an egg and always maintain a state of turbidity.” Fermenting wine is forced into circular motions, rising up the concave sides and then falling down the middle. The wines’ continuous motion carries everything in its wake, including lees. “If you look in the top,” says Beckham, “you can see the vortex. In fact, we don’t have to do any battonage!”
Beckham also tests firing temperatures to make vessels with different levels of porosity. As the firing temperature increases, the pot becomes less porous. He fires the pots over a spectrum of 100 degrees. “Those at the lower end of the temperature spectrum weep and sweat—the wines have more gas exchange and are the most expressive,” he says. “At the high end of the spectrum, the vessels are vitrified and the wines are much more reductive and the vessel is tight.” That’s allowed him to experiment as a winemaker would in deciding to use oak barrels from a particular forest, or cooperage because of its grain size and toasting. In general, Beckham finds that the clay allows oxygen into the wine twice as fast as wood. But the subtleties of oxygen transfer at each temperature constitute additional variables that he and other winemakers can use to their advantage.
Vessels fired at higher temperatures have practical benefits: None of Beckham’s vessels need to be buried underground to prevent leaking, or to be lined with beeswax, as classic qvevri would. And while lined clay is usually easier to clean, these unlined pots can be cleaned with high-pressure hot water without fear of cracking the pots.
In his efforts to better understand clay-aged wine, Beckham tracks a slew of other analytics. He notes that the clay reacts enzymatically with wine and raises its pH by pulling out acids. “I took a Riesling with a pH of 2.8, and in just two months, it went to 4,” he says. This effect can be lessened by treating a new pot with hot water, and it can be used practically to soften the edges of very acidic wines.
Another benefit of clay is its natural clarification properties. While many winemakers stir in negatively charged diatomaceous earth to fine their wine, clay pots have this property built in. “If you look at a wine aged in clay versus wood,” says Beckham, “the wine in clay will look like it’s been fined.”
Beckham uses homemade clay vessels for his A.D. MMXV Amphora series wines, including two Pinot Noirs, a Pinot Gris, a Grenache, and a Syrah-Viognier. All this work has been leading Beckham to bringing a proprietary vessel to the market, which he’s calling Novum. “I want people to go into wineries and say, Oh that’s a Novum—like someone might say of Kleenex,” he says. The 350-liter vessels are shaped like the wide-mouthed, flat-bottomed dolium. With Novum, Beckham anticipates producing and selling 50 vessels for the forthcoming 2018 vintage, with plans to expand production in 2019. The price has yet to be set but most likely will be several thousand dollars.
After the near-extinction of clay vessels from the world of winemaking, it’s fascinating that they’re reemerging in Old and New World countries. And while McGovern continues to lead the historical research at the University of Pennsylvania Museum, he’s looking excitedly to the future, sensing that today, as in the past, “this area of research and practice should dramatically transform the world of wine.”
Peter Weltman is a sommelier and entrepreneur based in San Francisco who explores native grapes from ancient sources. He writes for global food publications, gives speeches on wine activism, and creates immersive experiences about his movement, #BorderlessWine.
