- a method of removing solid matter or impurities from a wine by adding a substance to the top of the bottle or barrel and allowing it to sink down through the liquid, gathering the impurities as it sinks. The original substance used for this purpose was egg white, but fine clay called bentonite is now used as a more effective agent. Fining, like filtration, improves the colour of a wine and provides a clarity to the liquid. It also removes any unwanted bacteria and yeasts still present in the wine that might continue to ferment once the wine has been bottled. Fining is now avoided by most producers of fine wine.