Both fining and filtration are treatments that can be done to further polish or finish the wine just before bottling.
Fining works by introducing an agent to the wine that physically binds with a targeted element, most commonly tannins or proteins. Once the reaction finishes and the agglomeration precipitates out to the bottom of the vessel, the wine is racked to remove it from the sediment.
Filtration works by passing the wine through a material that contains a series of very small holes (or “pores”) similar to a coffee filter. Liquid and particles small enough to fit through these holes are allowed to pass through; particles that are too large get held back and are effectively removed from the liquid.
Depending on what is going on in our wines, we may decide to do one, both, or neither of these treatments. It all comes down to our personal winemaking philosophies and whether or not we feel the wine needs maintenance.
More information on fining and filtering wine can be found in our Red Winemaking and White Winemaking manuals.