What's that in my wine: tartrate crystals

Source: http://tablascreek.typepad.com/tablas/2011/05/whats-in-my-wine-tartrate-crystals.html

Armagnac Baron de Lustrac Armagnac Baron de Sigognac Armagnac Baron de Sigognac ans Armagnac Chateau de Laubade NV Armagnac Clos des Saveurs