In the Madeira solera system, the wine of a single grape variety is kept for decades. Then occasionally some wine is drained and sold, a maximum of 10% at a time. The vessel is then refilled with new wine from the same grape. In total, the winemaker is allowed to undertake this process 10 times, after which the entire barrel must be bottled at once. The solera system provides a wonderful blend of flavors: the old wines in it provide intensity and complexity, the young wines count for a fresh vibrancy.