and are found in various concentrations in many blends and vintage wines. Bastardo, Complexa, and Tinta Negra are red grape varieties. Regulations enacted recently by the European Union have applied the rule that 85% of the grapes in the wine must be of the variety on the label. Thus, wines from before the late 19th century (pre-phylloxera) and after the late 20th century conform to this rule. Many "varietally labelled" Madeiras, from most of the 20th century, do not. Modern Madeiras which do not carry a varietal label are generally made from Negra Mole. Other varieties planted on the island, though not legally permitted for Madeira production, include Arnsburger, Cabernet Sauvignon, and the American hybrids Cunningham and Jacquet. Winemaking The initial winemaking steps of Madeira start out like most other wines: grapes are harvested, crushed, pressed, and then fermented in either stainless steel or oak casks. The grape varieties destined for sweeter wines – Bual and Malvasia – are often fermented on their skins to leach more phenols from the grapes to balance the sweetness of the wine. The more dry wines – made from Sercial, Verdelho, and Negra Mole – are separated from their skins prior to fermentation. Depending on the level of sweetness desired, fermentation of the wine is halted at some point by the addition of neutral grape spirits. The younger wines (typically 3 and 5 years old) undergo the estufagem aging process to produce Madeira's distinctive flavor by artificial heating, whereas the wines destined for long aging are barrel-aged using only the naturally high temperatures of the barrel storage rooms (see canteiro process). Colourings such as caramel colouring have been used in the past to give some consistency (see also whiskey), although this practice is decreasing. The aging process What makes Madeira wine production unique is how the wines are aged in relatively high temperatures, meant to duplicate the effect of a long sea voyage on the aging barrels through tropical climates. Three main methods are used to heat the wine during aging. The two processes belong to the estufagem process (estufa means hothouse or stove in Portuguese), in which artificial heat is used to accelerate the aging process of the wines, whereas the canteiro process is used for the older and more expensive wines and employs only the natural heat of the barrel warehouses. Estufagem processes: Armazém de Calor: Only used by the Madeira Wine