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June 15, 2021 62 min

Oak stabilizes color and smooths tannins, some think of it as a seasoning ingredient. But what about the other vessels that are increasingly popular for fermentation and aging? What do they do and are they really more than hype? We discuss the main alternatives to oak -- concrete and amphora, what each does and the benefits of each.

Photo: Concrete eggs made by Sonoma Cast Stone 

The show is a hybrid of discussion and interview, as I welcome Steve Rosenblatt of Sonoma Cast Stone, who manufactures custom concrete eggs and tanks, and Debbie Passin of who sells custom, next generation amphora.

Photo: Vinethos

We start at the beginning and explain the purpose of all vessels for fermentation and aging.


For winemakers looking for good texture and small transfers of oxygen to smooth the tannins in reds and provide a good medium for sur lie aging in whites, but who don't want the oak flavor, they have a few choices.

  • They can use aged, neutral oak barrels. These neutral barrels provide the benefits people seek but they do absorb a lot of wine, are hard to clean, and don't always keep the fresh flavors of the wine. 
  • They can use stainless steel tanks or smaller stainless steel drums. These are great for wines that don't need any oxygen, as they keep flavors fresh and clean. They are temperature controlled, easy to clean and sanitize, and they allow the wine's flavor to shine. For those who want a more intense flavor, the smaller vessels will allow more contact with the lees (dead yeast cells that break up and give nutty, breads flavors to the wine). 
  • Photo: Quality Stainless Tanks 

    But what if you want the benefits of oak without the flavor? That's where concrete eggs and amphoras come in. 

    We first address concrete, which is at this time, a bit more popular than amphora. The main benefits we discuss:

  • The shape of the egg allows for continuous flow to the wine as it ferments and matures, creating a more homogenous wine.
  • As fermentation creates heat, convection currents move the wine around, as it does in a tank or barrel. The currents are so strong, that the wine barely needs to be punched down or pumped over during fermentation. Battonage (stirring lees for increased flavor) also is barely needed. The lack of corners in the container mean there are no "dead areas" and the wine is more complex and uniform in quality and texture.
  • Tannins are softened during maturation: Similar to the benefits during fermentation, the egg shape constantly circulates the lees as the wine matures after malolactic fermentation so the tannins in reds are softer and finer with age in eggs.

  • Insulation: Concrete can be up to six inches thick so there is natural insulation from outside temperature swings that stainless steel tanks cannot provide without cooling or heating coils. This allows wine from concrete eggs to maintain freshness.

  • Oxygenation (with a caveat): Unlined concrete allows tiny amounts of oxygen to permeate and come into contact with the wine (from inside of the tank when it first is put in the tank). This softens tannins, creates complexity, texture, and a better mouthfeel especially during fermentation. The wine is fruity without any oak flavors.
  • Beauty and sustainability: The vessels are beautiful, can be customized, and they last forever if they are taken care of – score for sustainability!

  • Ease of cleaning in a fermentation or aging vessel is really essential in wine. Sanitized vessels = clean wine. Concrete is easy to sanitize and clean.
  • Photo: Steve Rosenblatt, Sonoma Cast Stone

    After we set up the history and benefits of concrete, I welcome the wonderful Steve Rosenblatt, founder and owner of Sonoma Cast Stone (and hobbyist winemaker!), the only manufacturer of concrete eggs in the United States, who gives us incredible detail on these benefits and more.

    Next, we discuss amphoras. The benefits are largely the same (shape allows convection, clay is great for insulation, they are beautiful and sustainable, and easy to clean) but the real difference is porosity of amphoras, which mimics oak without flavor more than concrete…

  • True mico-oxygenation...Amphoras are made of clay and the newest generation have materials that can be fired at very high temperatures (in a kiln). These new amphoras don’t impart flavor, don’t crack or leak, and they have small pores, which allow for slow and steady micro-oxygenation similar to oak. The wine has complex texture, tannins relax over time, and lees are integrated into the wine. The difference: the grape and terroir are preserved with no oaky flavor.
  • Photo: Deborah Passin of

    Deborah Passin of VinEthos, who sells the top amphora producer, helps explain amphora and, importantly, dispel the myth that somehow amphora are only for natural wine or for funky, oxidized styles.  Amphoras are great vessels for all wine.


    I learned so much in this show – I hope you will too!


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