Our friend Jeremy Parzen commented on Montalcino Report and asked what the name of the glass device on the top of the botte in my last post. It is called a "tappo colmatore" in Italian and a "hydraulic bung" in English. It works by allowing the gas from the wine to escape while it still keeps the botte full. I found this illustration above to show how it works. As the wine is aging, it releases some gas but at the same time you do not want oxygen to enter the botte and to come into contact with the wine (because that would oxidize the wine and create unwanted aromas). By keeping the bottom chamber filled with wine racked off from other barrels as the wine is aging, the gas is released with out any oxygen entering the barrel since the gas can escape through the bung. Thank you Jeremy for your question.
