Grape Cap Winery Punch

When Joel Peterson of Ravenswood Winery, in Sonoma, California, made his first Zinfandel wine in 1976, he used dry-farmed (non-irrigated) grapes from old vines and fermented them in open-top casks. He also used this 5-foot-long aluminum tool made by a local metalworker to “punch down the cap.”
During fermentation, a solid mass of grape skins, stems, and seeds (the “must”) rises to the top of the fermentation vessel, typically a wooden cask or metal tank. The cap must be broken up and stay moist to benefit the wine’s color and flavor, which results from the mixing of yeasts into the must and the dissipation of bacteria-friendly heat that occurs during the course of normal fermentations. The winemaker has to punch down the cap several times a day while fermentation is underway.
To carry out a punch-down, the winemaker stands above the tank and, with a great deal of strength, shoves the punch into the cap, breaking it apart and keeping the must moving. Many modern winemakers prefer using electric pumps to do “pump-overs” in closed tanks or rotary tanks to swirl the wine, both the mechanical equivalent of the old-style punch-down by hand. The open tank punch-down remains the artisanal practice to date, and it is still used by winemakers from Oregon to France.
Physical Description
metal (overall material)
overall: 58 in x 9 1/2 in x 12 1/2 in; 147.32 cm x 24.13 cm x 31.75 cm
ID Number
accession number
catalog number
Credit Line
Gift of Joel Peterson
See more items in
Work and Industry: Food Technology
FOOD: Transforming the American Table 1950-2000
Food: Transforming the American Table, 1950-2000
Exhibition Location
National Museum of American History
Data Source
National Museum of American History


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