Fining

Fining is the process of clarifying and stabilizing a wine. A fining agent is mixed in to bind with particles suspended in wine that would make it appear cloudy when poured into a glass. Since fining agents are slightly heavier than wine, the bound particles precipitate out and settle to the bottom of the tank. Afterwards, the clarified wine is carefully racked off the settled material into a new vessel.

There are several types of fining agents commonly used to target specific faults. Bentonite is a type of clay used to remove protein compounds that can cause a wine to appear hazy. Protein based agents, such as casein and albumin found in milk and egg whites, can remove excessive tannins and astringent phenols along with helping to clarify the color of a wine. Trace amounts of copper sulfate are sometimes used to remove aromas associated with reduction.

Excessive fining can strip a wine of body and color, so any fining should be approached with caution.