From the moment when the boiled must is put into a 60 liter cask, to the moment the finished product leaves the acetaia as table-ready balsam vinegar, at least 12 years will have elapsed. Up to 25 years are needed to earn a product the distinction aceto extra vecchio. During this period, the must is successively decanted (an operation called rincalzo) into a series of five barrels, each of a different wood, each smaller than the previous barrel, each lending its special aroma to the liquid inside.
The initial cask, generally of oak, contains about 60 liters. The balsamico then moves to the second chestnut cask (50 l.), and so it continues on its way to casks of cherry wood (40l.), ash (30l.) and mulberry (20l.).

In other words, the original volume of must is reduced by two-thirds by means of this long and complex process. For this reason, the true aceto balsamico tradizionale di Modena, particularly the extravecchio (aged 25 years), costs considerably more than the most expensive vintage champagnes.

Balsamic vinegar barrels:
each barrels is made of a different wood.

The rincalzo: It's all in the family

After having been boiled, the must is filtered and cooled before being transferred into a 60-liter oaken barrel. This decanting procedure, known in Modena as the rincalzo, is a veritable ritual, its rites differing somewhat from family to family.
It goes like this: a quantity of mature, table-ready aceto is drawn off the final mulberry barrel, which is then refilled from the barrel made of ash and so on down the line each barrel refilled from the preceding until, finally, the large oaken barrel is refilled with a new batch of boiled and cooled must. The rincalzo normally takes place in spring, but many of the family-owned and operated acetaie have their own ideas...

The very barrels used for ageing aceto balsamico, often a century old, are highly prized. So much so, in fact, that Modenese estate executors have actually found themselves involved in legal battles among the heirs over their rightful ownership.