The Solera method is at the origin the traditional method of aging sherry.
The method consists in arranging barrels into superimposed rows. Each row is composed of rums of the same average age. The barrels thus stored form stages of 3, 4, 5 and up to 8 levels.
A solera is literally the row of barrels placed in the bottom, where alcoholic beverages are more aged, while a criadera is the row placed in the top of the pyramid, where alcoholic beverages are younger.
The method is starting to fill only the high barrels; after a year one part of the content is decanted into barrels that were located at the lower level and the upper ones are filled with the new wine or distilled.
The process is renewed from year to year, so that the drink in barrels at the base ready to be consumed is composed of products of different vintages, that contribute to give it a distinctive flavor.
The Solera method can also consist to associate different types of barrels: old barrels of bourbons, sherry, port wine, etc.