Solera System: Fractional Blending (Sherry, Madeira, Some Ports)

The solera system is a multi-tiered barrel arrangement where wine moves through progressively older age stages in a predetermined sequence. In Jerez it is called the criaderas y solera system, and the Consejo Regulador describes it as a dynamic system in which wines from different stages of the ageing process are blended together to perpetuate specific characteristics in the wine finally sold. Each solera is made up of several scales, or tiers, each composed of a number of butts. The tier holding the oldest wine sits at floor level, and the term solera derives from the Spanish word for floor, suelo. The tiers above it hold progressively younger wine and are called criaderas (nurseries), numbered by their closeness in age to the solera. Wine for bottling is drawn only from the solera, which is then replenished from the primera criadera (first nursery), which is in turn refilled from the segunda criadera (second nursery), and so on up to the youngest tier, which receives young wine from the añada system.

• Solera: the oldest tier, at floor level, which produces wine ready for bottling; the Jerez rules define it as the final ageing scale, drawn for shipment or for later blends (cabeceos)
• Criaderas: the intermediate tiers, numbered by closeness in age to the solera (1st criadera, 2nd criadera, and so on)
• Each tier is formed of butts holding wine of a homogeneous level of age
• A saca takes only a specific proportion of the wine in each butt, leaving the butts partially empty

During each racking (trasiego), the winemaker draws a fraction of wine from the solera - called the saca - and prepares it for bottling. That same volume is replaced from the primera criadera in an operation called the rocío (sprinkling). This creates a cascade upward through every tier until the youngest criadera is topped up with young wine from the añada system. The whole process of carrying out the sacas and rocíos in a solera is called correr escalas (running the scales). The Consejo Regulador calculates the average age of a solera's wine by dividing the total volume of wine in the system by the volume extracted from the solera each year; under its norms, and so that no sherry reaches the market with less than two years of ageing, that ratio must be greater than two.

• Saca (taking out): the periodic extraction of a specific proportion of the wine in each butt of a tier
• Rocío (sprinkling): topping up, or refreshing, the space created in a tier with wine from the next younger tier
• Trasiegos: the movements of wine within the solera, carried out by specialist bodega workers called trasegadores, who homogenise the wine in each butt after the rocío without disturbing the flor or the cabezuelas (fine lees) at the bottom
• Average age: total volume in the system divided by the annual volume extracted; the Consejo Regulador requires this ratio to be greater than two
• How often the operations take place and what proportion is extracted are dictated by the wine's characteristics

The Consejo Regulador says the solera system maintains the characteristics of the wine in the solera while eliminating the variations that occur between one vintage and another, and that the oldest wines benefit both from being refreshed with young wines and from the characteristics acquired over years of crianza. For biological ageing under flor the system is essential: the flor yeast needs micro-nutrients, which are supplied by adding small quantities of young wine, and the Consejo Regulador calls criaderas y solera the only viable method for successfully carrying out biological ageing. Each transfer also dissolves some oxygen in the wine, stimulating regeneration of the flor; in wines aged without flor, the oxygen introduced during these operations accelerates oxidative maturation.

• Labels may refer to the year the solera or the bodega was founded, provided it can be documented and does not cause confusion
• Flor nutrition: successive refreshments carry small quantities of young wine to the oldest scales, supporting vigorous biological ageing
• Oxygen: moving the wine dissolves oxygen that stimulates flor growth in biologically aged wines and accelerates oxidation in wines aged without flor
• Merma: evaporation of 3 to 5 percent a year, mostly water, continually concentrates the wine's other components

According to the Consejo Regulador, the criaderas and solera system, bodega architecture, and Jerez wines as they are known today began to take on their distinct characteristics in the late 18th century, when the prolonged storage of wines from different harvests and the need to supply the market with a wine of consistent quality gave rise to the method. The ageing of sherry must last a minimum of two years, either in criaderas y solera or in the static añada system, in which the wine of each harvest is aged separately without blending. In 2000 the Consejo Regulador created two certified-age categories, V.O.S. (Vinum Optimum Signatum, over 20 years) and V.O.R.S. (Vinum Optimum Rare Signatum, over 30 years), certified for each individual saca by an independent Tasting Committee supported by laboratory analyses that include Carbon 14.

• Origins: in the mid-18th century, wines exported from Jerez were very different to what is now recognised as Sherry; the modern system took shape in the late 18th century
• Minimum ageing: two years, by criaderas y solera or by the static añada system
• V.O.S. and V.O.R.S.: created in 2000 for wines of over 20 and over 30 years, limited to Amontillado, Oloroso, Palo Cortado, and Pedro Ximénez
• 12 and 15 years: certification covers the whole system of criaderas and soleras, with annual sales of one-twelfth or one-fifteenth of the stock
• Sales quota: in general terms, for each litre sold three litres must remain in stock, so all sherry sold is at least three years old

González Byass, whose founder Manuel María González Ángel entered the wine business in 1835, makes Tío Pepe, a Fino from Palomino Fino grapes aged for approximately 4 years in the criaderas and soleras system. The brand refers to José Ángel y Vargas, González Ángel's maternal uncle, and the bodega's founding solera butts were labelled 'Solera del Tío Pepe'. Lustau's East India Solera is a cream sherry: Oloroso and Pedro Ximénez are each matured separately in their own solera for 12 years, then blended and returned to a 45-cask solera for a further 3 years. Beyond Jerez, Wine Spectator describes the solera process as common to Sherry, Madeira, brandies, and some Ports and whiskies. Marsala's in perpetuum system, which Wine Spectator likens to the Sherry solera, also works as a cascade: wine is drawn each year from the barrels holding the longest-aged blend, each is replenished with the next oldest wine, and the barrel with the youngest blend is replenished with new wine from the latest harvest.

• González Byass Tío Pepe: Fino from Palomino Fino, aged for approximately 4 years in criaderas and soleras
• Lustau East India Solera: Oloroso and Pedro Ximénez, 12 years each in separate soleras, then 3 years in a 45-cask solera; 20% alcohol, average age 15 years
• Madeira and some Ports: Wine Spectator lists them, with brandies and whiskies, among the users of the solera process
• Marsala in perpetuum: a year-by-year cascade from the longest-aged barrels down to new wine from the latest harvest

The standard sherry vessel is the 600-litre American oak butt; for biologically aged wines, butts are deliberately filled to only about 500 litres, leaving headspace for flor yeast to form its protective surface film. The Consejo Regulador names this butt, equivalent to 36 arrobas and also known as a bodega butt, as the preferred and most widely employed type, and says butts for ageing under flor are filled to 30 arrobas (500 litres), leaving a space of 'two fists' of air. Fortification sets the path: wines for fino and manzanilla are fortified to 15% by volume, enough for the flor to form but intolerable for other micro-organisms, while wines for oloroso reach at least 17%. Above 17%, biological activity cannot be sustained and not even the flor survives. Butts are thoroughly wine-seasoned before being put into service for ageing. Evaporation through the wood, called merma, accounts for losses of 3 to 5 percent per year of the total wine stored; because the loss is essentially water, the wine's other components are continually concentrated.

• Butt: American oak, 600 litres; flor-aged wines filled to 500 litres (30 arrobas)
• Rules: ageing in oak butts of no more than 1,000 litres, with historic exceptions recognised by the Consejo Regulador
• Fortification: 15% by volume for fino and manzanilla; at least 17% for oloroso
• Flor limit: above 17% by volume, biological activity is impossible to sustain
• Merma: 3 to 5 percent annual loss, mostly water, which concentrates the wine

Primary sources: https://www.sherry.wine/sherry-wine/production/ageing, https://www.sherry.wine/sherry-wine/special-categories, https://www.sherry.wine/sherry-wine/production/fortification, https://www.sherry.wine/sherry-region/history-of-sherry, https://www.sherry.wine/documents/597/21052026_Pliego_Jerez_1wBQg8y.pdf, https://www.tiopepe.com/en/node/41, https://www.gonzalezbyass.com/en/wineries-and-brands, https://lustau.es/en/coleccion/rare-and-vintage,sherry-wines/cream-east-india/. Secondary sources: https://www.winespectator.com/glossary/index/word/solera, https://www.winespectator.com/articles/sicilian-wine-s-unfinished-poem. Last verified 2026-09-25