Another aptly-named tank! Open-top tanks offer winemakers the most cap management options since they allow complete access to the cap for punchdowns, but also have the necessary valves for pumpovers. They will typically have a 1:3 surface area to volume ratio, and temperature control. The biggest concern with red ferments in these tanks are keeping fruit flies out, easily remedied by covering with a mesh screen. Niven Family Wine Estates has the best of both worlds: stainless steel tanks with removable lids, allowing tanks to convert from open-top fermentors to multi-purpose tanks.
Rotary tanks produce high extraction due to their horizontal orientation, which creates a very high surface area to volume ratio, and their unique cap management. A rotary tank will sit on a set of rollers and attached machinery can spin the entire tank, meaning vigorous cap management with minimal manual labor. The high rate of extraction allows winemakers to press the wine off skins earlier in fermentation and avoid phenolic extraction. Thus, these tanks tend to producer rounder, fruit-driven wines that are approachable sooner than wines fermented in other vessels. Rotary tanks require a significant amount of infrastructure and space, while also having limited usability outside of the vintage period.
Oak Barrels and Tanks
More winemakers are integrating oak fermentation into their red wine programs. Some wineries have begun removing one head of a new, 225-litre (60-gallon) barrel to use for on-skins ferments. They then press the must off skins, put the head back on the barrel, and re-fill it with the resulting wine. There are also varying sizes of wooden tanks available in today's market, including temperature-controlled options. Proponents of fermenting reds in oak contend the wine benefits from increased color stability, fuller mid-palate structure, and better oak integration. Many winemakers are opting for the addition of oak adjuncts (oak chips, oak dust, etc.) to tank ferments.