Fermentation

Wort is the pumped into the washbacks which are large and open fermentation vessels, which can hold up to 70.000 litres and be as high as 5 or 6 m. They may be covered by detachable panels and are usually made of Oregon pine.
Some distilleries use fully closed vessels made of steel which are easier to clean.Yeast is added, being either distillers yeast or a mixture of the latest with brewer yeast, and will start fermentation. The action of yeast on wort's sugar will produce alcohol and carbon dioxide. Wort will bubble, and may even in some occasions generate strong vibrations of the washback itself in spite of its impressive size.
After about 48 hours, bubbling and fermentation are over and the wort has been transformed into wash, an alcoholic liquid of 7 to 8% vol. and not unlike a sort of crude beer, which is pumped into the wash charger.