Madeira is made in a number of different ways and methods of production vary enormously according to the market and the price that the wine commands. Production revolves around the use of the estufa system and its natural alternatives.
The estufagem process has been much improved in recent years with concrete tanks having been largely replaced by stainless steel (cubas de calor) ranging in size between 20,000 and 50,000 l/13,200 gal and most widely used for large-volume production. Hot water circulates either through a stainless steel coil in the middle of the tank or a jacket, heating the wine to a maximum temperature of 55 °C/130 °F for at least 90 days. The process is carefully monitored by the wine industry’s controlling body IVBAM (Instituto do Vinho, do Bordado e do Artesanato da Madeira) which also, rather quaintly, represents Madeira’s other traditional industries, embroidery and handicrafts.