Fining is a process that clears your wine after fermentation is complete. It also stabilizes the wine by speeding up the formation and precipitation of excess tannins, unstable proteins and other microscopic matter that could form after the wine is bottled.
When a fining agent is introduced to the wine, it binds to these particles, and both fall out as sediment. Fining agents accomplish this through “polarity.” By introducing a fining agent that has the opposite electrical charge as the particles’ charge, the two are easily attracted to each other and become too heavy to stay dissolved in the wine.
This important process compresses the time-frame in which the particles would naturally precipitate (under good conditions). It also helps eliminate compounds that can form haze or cloudiness, usually due to unstable proteins. In short, it brings your wine to the dinner table sooner, clearer and more stable.
Generally, white wines benefit from fining by having their lighter color preserved and their proteins stabilized. Red wines require fining to lessen their harsh tannins.
Some fining agents work best when used in combination with other fining agents: The fining properties are enhanced, balanced and fine-tuned. In some cases, certain fining agents must be used in combination with other agents, or else they may create their own clarity and stability problems.
Here’s a rundown on various fining agents available to home winemakers.
This fining agent, which has enjoyed success in the U.K. home winemaking market for about ten years, is one of the most effective to date. It’s a two-step procedure that uses two compounds: kielselsol (inorganic) and chitosan (organic).
First, kieselsol is used to build up the negative charge in the microscopic matter in the wine. This maximizes the effectiveness of the very positively charged chitosan. Chitosan is a natural product made from de-acidified crustacean shells. Due to its non-allergenic properties, it’s also used in water-treatment systems and the manufacturing of bandages. I’ll provide more information on kieselsol later.
Claro-K.C. is very easy to use. It clumps and compacts very well — well enough, in fact, that filtering is not required to separate the fined wine from the rather solid, pancake-like sediment gathered at the bottom of the carboy. Wines treated with this method usually acquire a star-bright appearance.
The product comes in pre-measured form for the usual batch sizes and is widely available. While instructions do come with the product, please note that the addition of tannin is required twenty-four hours prior to treatment when fining your white wines.
One of nature’s kindest offerings to the winemaker is bentonite, a montmorillonite clay that not only clarifies grape juice and wine, removes heat-unstable proteins, aids in settling matter and deters other problems but can also help correct the overuse of other fining agents. It is an excellent fail-safe when other treatments don’t “take.”
The preferred type is Wyoming bentonite. This is a sodium bentonite that has a “swelling capability.” In layman’s terms, this means that in solution of 700 to 800 meters squared per gram, the bentonite separates into individual “sheets” of aluminium silicate that are 1 nanometer (nm) thick and 500 nm wide. This provides enormous surface area for bonding with particulate matter, in addition to the positive-negative attraction between the bentonite and proteins.
Bentonite is a wonder for white wines. By removing heat-unstable proteins from wine (such as Muscats, which have them), the wine achieves protein stability. Bentonite can also clarify the musts of more basic whites, before or during fermentation, by removing matter that would make wine look darker, taste harsher and foster cloudiness. For top-quality whites, it shouldn’t be used until after fermentation is complete, because some of the particulate matter provides complexities of flavor that would otherwise be diminished. When bentonite is used after fermentation, it aids in settling out lees more quickly and reduces time between rackings.
The main disadvantage of bentonite is that it works best when the wine is at room temperature while being racked and then kept this at this temperature until its next racking, ten to fourteen days later. If the wine is allowed to cool, some of the bentonite will go into suspension, and this will compound the fining problem. One way to overcome this is to fine with bentonite during the warmer months (less bentonite may be required to do the job). A note: Heavy bentonite use may lessen a wine’s complexity.
Bentonite is not usually used on red wines, as it may contribute to drastic loss of color. Red wines have a higher tannin content than white wines, and this already helps to remove unstable proteins and aids in clarification. Lastly, bentonite contributes to some loss of wine by generating lots of muddy sediment.
Bentonite is widely available, and instructions come with it. Here is the general approach for a five-gallon batch:
- Blend together between 10g (just over 2 tsp.) and 20g (4-1/2 tsp.) bentonite (depending on how warm your work area is) and one-half cup of warm water. Stir vigorously or mix in a blender for three minutes on medium setting.
- Cover and let sit for 24 hours.
- Repeat the mixing step.
- Stir the mixture into the wine and leave it for 10 days (minimum).
- Rack the wine off the sediment into a sterilized (sulphited) carboy on a slight angle to force the sediment into one side of the carboy’s bottom. This makes for easy and clean siphoning because bentonite does not solidify or compact.
Agglomerated bentonite (found under the KWK and Vitaben trade names) is also available. The directions are very similar to those above, but the sediment rendered is much more compact, resulting in less wine loss.
Isinglass is a protein-based substance extracted from fish bladders (mainly sturgeons). It’s an effective fining agent for either white or rosè wines. It can be used in place of bentonite and may be the only fining agent required.
Isinglass works by attracting negatively charged particles and requires some added tannin to maximize its attractive properties. The tannins provided by adding extra oak chips to your wine will usually do the job. In the absence of oak, add 1/4 to 1/2 tsp. of tannin per five-gallon batch, either before or after adding the isinglass. Directions come with the pre-measured one-ounce bottles (the suggested amount to treat a five-gallon batch).
Two strong advantages should be noted. Isinglass has about the same clarifying properties as a final polish filtration, so filtration is not necessary. This may not seem significant, but, one must think, as I do, of all the complex flavor components lost in the filter. Also: Unlike most other fining agents, the overuse of isinglass is less likely to affect your wine’s end result.
There are drawbacks, however. Isinglass is more expensive and is rather fussy to store properly. It has a short shelf life and should be kept constantly cool. If it is exposed to (or stored in) warmth, it will reduce to a gelatin-like state — a rather simple solution that will lose its fining properties. Isinglass also has a fishy smell that does not transfer (thankfully) to the wine.
This is a suspension of silicon dioxide that is available in both positive and negative charge giving it broad applications. Kieselsol is often used with other fining agents, usually gelatin. It increases the negative charge of suspended matter, which maximizes the use of other fining agents.
Kieselsol can be formulated to remove both positively or negatively charged particles. In its alternate forms, it can act either as a trigger for other negatively charged particles or as a boost to another positively charged fining agent.
This fining agent is commonly used to remove bitter (polyphenolic) compounds in white wine. In tandem with gelatin (see next section), it is effective in removing the stickier microscopic particles.
Kieselsol is a very flexible fining agent. It also has the ability to increase another fining agents’ effectiveness. And it produces less sediment than most other agents and strips little color from red wines. It is widely available, comes pre-measured for typical batch sizes and is very easy to use.
Gelatin and Tannin
Since these two fining agents are usually used together, I will discuss them together. Gelatin is an albumin-like protein made from animal tissue that is used to fine both reds and whites. Its primary use is in removing excess tannins in wines. The gelatin provides a positive charge to attract the negatively charged tannins.
Tannin comes from insect galls (abnormal outgrowths) on oak trees. In tandem with gelatin, tannin forms a meshwork that “sweeps” colloidal proteins out. When used in combination with gelatin, the effect that tannin has on proteins in wine is similar to the one that tannin has when it reacts with the protein collagen in converting animal hides to leather. When we drink red wine, a tiny bit of leather is actually created by the reaction of tannins with the proteins on our tongues and on the insides of our cheeks!
Here are two approaches for gelatin-fining red or white wines. (The white wine procedure involves additional tannins.) Fining a five-gallon batch of red wine:
- Soak 1 tsp. (5mL) of gelatin fining in one-half cup cold water for 1 hour. Then stir vigorously.
- Bring mixture to boil. After it has boiled, remove from heat and stir into wine.
- Let the wine stand for 10 to 15 days. Then rack into a clean and sulphited carboy.
- Top up carboy with cold water; top with air-lock.
- Let wine mature 3 to 9 months before bottling.
Here is the general approach for a five-gallon batch of white wine:
Follow the directions for red wine above, but you will need to add tannin because white wines have little tannin. Remember: You must add tannin. Otherwise, much of the gelatin will stay in the wine, since it has little to bind to, and will not fall out as sediment. So, add 1/4 tsp. of tannin per gallon (or 1-1/4 tsp. for the five-gallon batch) to the wine twenty-four hours prior to adding the gelatin finings. Continue to follow the directions for fining red wine, but allow ten to eighteen days to pass before racking. Bottle the wine one month after fining.
Both gelatin and tannin are easily found and come premeasured, with detailed instructions with each wine kit. As mentioned earlier, trace amounts of gelatin may remain in the wine after fining, but this is not a problem if the proper amount of tannin is present (whether by design or addition). If there is not enough tannin present, the excess gelatin may cause the treated wine to cloud. If unsure, use a ratio of fifty-fifty, gelatin to tannin.
Polyvinyl polypyrrolidone is a resinous polymer that works like protein-based agents in binding tannins. Its specialty is removing brown and amber pigments in whites. It also excels at removing brown tannins in whites and absorbs color and odor.
PVPP is not so much a fining agent as it is a clarifier of oxidized polyphenols. The approach is to create a warm slurry with a half-cup of warm water and a tablespoon of the PVPP. Stir the slurry into the wine and stir up the mixture a few times per day. The amount of time until racking will depend on how successful the PVPP is, given the amount of particulate matter in the wine. PVPP is neutral enough that you can decide to repeat the treatment, if the results are not satisfactory the first time around.
PVPP is widely available. It activates spontaneously, functions well at room temperature, and it can be isolated from sediment and re-used.
The active ingredient in egg whites is protein albumin, which removes tannin by offering an opposite electrical charge. The albumin content makes for a desirable fining agent. It is a relatively gentle agent, especially for red wines: It absorbs the harsh tannins but leaves behind the softer, desirable tannins.
The approach is very straightforward. You can use the pre-measured pure form or you can separate the white from the yolk of one egg (since five or six eggs are recommended from a 59-gallon barrel, one egg is more than plenty for a 5-gallon batch). Whip the egg white into a froth and stir into the wine. Egg whites work in much the same way as gelatin does, with respect to their electrical-attractive properties and the need to add tannins when fining whites. Use a 50-50 ratio of egg whites to tannin, if you’re unsure when fining your white wines. Stick to chicken eggs.
Active carbon or activated charcoal is obtained through the dry distillation of wood or other materials containing carbon (such as bones, peat or plant material). It is very porous, with a high ratio of surface area-to-weight. It’s used primarily to remove pigment polymers that can cause amber or brown color in whites, particularly pale cream sherries. Smaller-pored carbon is used to remove off-flavors. Active carbon provides a large surface area in solution (500 to 1500 meters squared per gram), and its electrical charge absorbs many compounds. This method is a last resort, when other fining agents can’t tackle the problem, such as severe oxidization, strong tainted flavors or off-odors that other fining agents can’t handle.
Active carbon is easy to use. Make a slurry using two teaspoons of carbon with a half-cup of water and stir into the wine. Monitor the wine for any positive changes and rack as soon as it is clear.
There are disadvantages with using active carbon: It strips a lot of flavor, it can give off-odors, and it has oxidizing properties. It should be used with care. Finally, this method, as with any other fining agent, will not work on wine made from tainted fruit (with aspergillus mold, for example). This fining agent is widely available.
This is a milk protein that, in connection with sodium or potassium ions, forms caseinate salt, which dissolves in wine. Released as salt, caseinate dissociates from wine, absorbs particles and aids in their settling. It is particularly useful in removing brown color from whites.
When added to cloudy wine, it reacts with some of the wine’s acid and forms a curd that absorbs and precipitates very small particles, including those pigments that cause discoloration.
Some drawbacks are that few winemakers use it, so it is hard to find. And it is seldom talked about in wine recipes in the hobby winemaking market.