A natural wine is a wine made,
- in small quantities,
- by an independent producer,
- on low-yielding vineyards,
- from handpicked, organically grown grapes,
- without added sugars or foreign yeasts,
- without adjustments for acidity,
- without micro-oxygenation or reverse-osmosis.
Most natural wines are neither filtered nor fined. The few that are will either be filtered extremely lightly or fined with organic egg-white. A natural wine contains no more than,
- 10 mg/l total sulfur if red,
- 25 mg/l total sulfur if white.
If sulfur dioxide is added, it will be only at bottling and only in the tiniest quantities. Many natural wines are made without the addition of sulfur dioxide at any point.
http://www.morethanorganic.com/definition-of-natural-wine
