Filtration and fining are cellar techniques used to clarify, stabilize, or polish wine. They are sometimes discussed as if they are automatically negative, but the reality is more practical. A producer may use them to remove haze, sediment, microbes, harsh phenolics, unwanted aromas, or instability before bottling.
Filtration
Filtration passes wine through a medium that removes particles of a certain size. Coarse filtration can remove larger particles. Sterile filtration can remove many microorganisms before bottling. The degree of filtration depends on the wine and the risk the producer is managing.
Filtering can help protect wines that contain residual sugar, have not completed malolactic fermentation, or are otherwise at risk of refermentation or microbial spoilage. It can also improve clarity.
Some producers avoid filtration because they want to preserve texture or because the wine is stable without it. Unfiltered wine may throw sediment or appear cloudy. Cloudiness is not always a fault, but it can be a warning sign if accompanied by off aromas or instability.
Fining
Fining adds a material that binds with compounds in wine and helps remove them. Fining can reduce bitterness, harsh tannin, haze-forming proteins, browning risk, or certain off aromas. Common fining materials have historically included bentonite, gelatin, casein, egg white, isinglass, PVPP, activated carbon, and plant-derived proteins, depending on goal and jurisdiction.
After fining, the material and bound compounds settle or are removed. The fining agent is not intended to remain as a major ingredient in the finished wine, but allergen and vegan concerns can still matter.
Vegan and allergen questions
Some fining agents are animal-derived. A wine fined with egg white, casein, gelatin, or isinglass may not suit vegan consumers. Producers increasingly use mineral, synthetic, or plant-based alternatives where appropriate.
Allergen labeling rules vary by jurisdiction. EoW should avoid broad claims such as "all fined wine contains X" or "vegan wine means unfined." Vegan suitability depends on producer practice and verification.
Does filtration strip wine?
Aggressive or poorly chosen filtration may affect texture or aroma, but careful filtration can be neutral and protective. The question is not whether filtration is good or bad, but whether it is appropriate for the wine.