Q. What do sparging and ullage refer to?

A. Sparging is part of the bottling process that helps to preserve wine freshness and prevent premature oxidation and other problems. After being rinsed and filled with wine, the bottle will have inert gas (usually CO2 or nitrogen) pumped into the neck to form a protective layer on top of the wine, rather than exposing it directly to oxygen.

When evaluating older bottles of wine for potential problems, the amount of ullage -- the level to which the wine fills the neck - is an important indicator. Young bottles are filled to a standard point below the bottom of the cork. As wines age, slow evaporation takes place and the ullage -- air space -- increases. Once the wine level falls to the sloping shoulder of the bottle, below the neck, it suggests that the wine may be getting a bit long in the tooth. Time to drink up!

Paul Gregutt answers questions weekly. He can be reached by e-mail at wine@seattletimes.com.