Issue link: http://winesandvines.uberflip.com/i/804714
April 2017 WINES&VINES 61 WINEMAKING Six years ago, shortly after the egg shape started to make in- roads in wine production, an egg- shaped tank made of oak was designed and produced by artisan Joseph François and exhibited at the 2011 SIMEI trade show in Milan. (See "Egg-Shaped Wine Tanks Whet Appetite" at wine- s a n d v i n e s . c o m . ) A t a b o u t $28,600 and 1,000 liters, the egg-shaped oak tank is undoubt- edly one of the most expensive tanks on a per-liter basis that has ever been produced. Today, however, the egg- shaped tank is usually constructed of concrete. In this new iteration, concrete as a tank material is of- fering alternatives for how wine can be made without oak. These tanks are "naked," meaning that the tanks do not have any coat- ings on the inside surface. New techniques are being de- veloped for the construction of these tanks by companies such as Sonoma Cast Stone. These tech- niques include some complex ac- cessories and provide additional utility to these tanks. Sonoma Cast Stone and another company, Vital Vessels, are both pushing the enve- lope in design and functionality. According to Steve Rosen- blatt, president of Sonoma Cast Stone, the company is in the last stages of patenting a new tank- construction process. The patent will secure the company's current innovations in tank design, add greater control over the final wine contact surface and provide more longevity to the tanks. In addition, the patent will include the company's development of new concrete materials. In Rosen- blatt's view, the new materials will offer greater ability to clean the tanks and leave less potential for any interaction (especially at first) of residual Portland cement with the wine. In concrete tanks, the Portland cement moves to the surface dur- ing curing of the concrete. As of now, before any concrete egg is used for wine, the tank's inside surface must be washed with an aqueous solution of 12% tartaric acid to remove residual Portland cement. After that process, wine- makers using these tanks should not scrub the inside surface or use hot water to wash the tanks. Hot water could crack a tank due to the unequal expansion of any stainless steel fittings such as manways and/or valve inserts. Scrubbing the surface could even- tually mar and/or gradually roughen and remove it. The construction of an egg tank is a process similar to con- structing a swimming pool. Flow- able concrete, embedded with fiberglass and other materials, creates the structural outside of the tank. Next, Sonoma Cast Stone adds PEX tubing to the in- side surface. The tubing will be used for their glycol chilling sys- tem that is embedded in this layer of the concrete wall of the tank. Once that process is finished, the final layer of very fine-grained materials is formed against a highly polished mold facing the tank's interior. Once cured, the mold form is removed, leaving a smooth production finish. The Sonoma Cast Stone tanks start at about 1,600 liters, and the cost is approximately twice that of stain- less steel tanks of equivalent size. Vital Vessels in Carmel, Calif., is another high-tech company making egg-shaped tanks—in this case using ceramic materials. The manufacturer's concept is based on KEY POINTS Tanks made of concrete have become increasingly popular in the past several years. While often impressive in size and shape, tanks made of concrete are heavy and therefore difficult to move. Innovations in egg-shaped tanks include manway-like lids, valves and support structures that allow the tanks to be moved. Alterna- tive materials such as ceramic and modern plastics also are being utilized to achieve many of the same goals as concrete egg- shaped tanks. TANNINS From harvest to pre-bottling, exclusive tannin products from BSG Wine help make your very best wines.