Balsamic begins with just-picked Lambrusco and Trebbiano grapes. They are cooked to a temperature no higher than 194 degrees -- to release their juices but not to cook away any of the flavor. The juice is cooled, filtered, then stored in barrels filled no more than 3/4's full. Many different types of wood, mostly castagno but also ginepro (juniper) and ciliegia (cherry) are used to make special reserve vinegars. As the vinegar ages and evaporates over years it is transferred from the large 'mother' barrel to smaller ones. The taste of vinegar that's years old is a rare treat.