NORMALLY a well-made wine will clear of its own accord, given time (which can be as much as a year in some cases) but when it does not, it may be necessary to resort to fining or filtering. The best advice that we can give, however, is: always give your wine a chance to clear naturally. Avoid fining, which may upset the chemical balance of the wine, and filter only as a last resort, for filtering does take something out of a wine besides the murkiness.
Usually all that is necessary is to move the wine, at the end of fermentation, into a much lower temperature (say from a warm kitchen to a cold larder or outhouse, but not into a refrigerator). In some cases, if you have some clear wine of the same sort from the previous year, pouring some of this in on top of the new wine will rapidly clear it.
If both of these methods fail to work, it may be necessary to resort to fining. The commercial wine world uses several types, organic (gelatine, isinglass, egg whites, egg albumen powder, pure ox blood, casein, etc.) mineral (Bentonite, Kaolin or Kieselguhr) and vegetable (alkaline alginates), but some of these are risky in the hands of the amateur, since they require a reasonably exact dosage calculated as the result of experiments, and it is difficult to work down to the smaller quantities we usually need. Many proprietary wine finings work on the simple principle that tannins and proteins precipitate one another and therefore add in turn some of each.
Many prefer to play safe and buy some reliable proprietary finings, with detailed instructions; I have found "Serena" wine finings, supplied by Grey Owl Laboratories, and Klarwunder, from Semplex, good.
Failing this, a good general-purpose fining for both red and white wines is egg-white; one egg-white, thoroughly beaten into half a pint of the wine with a tiny pinch of salt will clear up to 10 gallons.
For white wines try first two or three drops of milk, for red wines up to eight square inches (i.e. 2 inches by 4 inches) of leaf gelatine. Soften it in water, dissolve in hot water, and stir it in.
If your wine remains obstinately cloudy, you can try using filter paper (Green's No. 940 or 960 is ideal) which should be folded in a series of vertical creases to present the maximum area to the wine. Fold your paper in halves, then quarters, then eighths; then unfold and refold it between the original creases, but the opposite way. It will then present a fluted appearance. A small plug of cotton-wool placed in the funnel before the filter will prevent a disaster if the bottom point of the filter paper gives way! These papers are really efficient and fast-filtering, and admirably suited to the home winemaker's purpose, unlike others which have been sold which, whilst—useful in the laboratory, are dreadfully slow in operation, and have led winemakers to the (mistaken) opinion that filter-papers are useless to them. Even ordinary tissues, used double or treble thickness, will provide a reasonable filter.
But you may be looking for one method of fining or "polishing" that can be applied to all your wines, and that can be employed for removing hazes as well. For many years amateur winemakers preferred to use asbestos pulp, but this method is now open to suspicion in that it may be a health hazard, and we therefore do not recommend it.
By far and away the best method of clarification is fining by means of BENTONITE (AI2O3. 4SiO2.xH20.), an excellent clarifying and stabilising agent. A montmorillonite clay which can absorb ten times its own weight of water, with which it forms a gelatinous paste, it causes a coagulation of the proteids, which increases proportionally as the acidity of the wine is greater and the tannin content smaller, and its action appears almost miraculous.
It can be purchased from Semplex, Rogers Mead Ltd., Boots, and most other wine supplies firms, and should be used at the rate of H oz. of Bentonite to 3 fl. oz. of water. Since it will keep indefinitely, but has to be made up at least 24 hours before use, it pays to make up a quantity at a time, and preferably to do so at the outset in two small containers, so that when one is used up it can be immediately replenished, and the suspension in the second container will have been standing for weeks, or even months, and will be ready for use.
Use 1 pint bottles with flat bottoms and screw caps; fruit juice bottles are ideal. Into each bottle pour 9 fluid oz. of water (boiled and then cooled) and then funnel in 4 oz. of Bentonite. Screw on the cap and shake vigorously, impacting the liquid against the flat bottom of the bottle to force the Bentonite into suspension. Then leave the bottles for at least 24 hours, and preferably more, before use, to allow the montmorillonite particles to swell and become effective coagulators.
To use the suspension, remember that in each bottle you have H oz. of Bentonite. The advocated dose for all ordinary hazes or straightforward fining is 1/8 of an ounce per gallon of wine, and for really bad hazes H oz., so you will need to use one-sixth of the contents for "normal" fining, and one-third of the contents for really thick hazes.
The wine should, of course, have been racked off any deposit. Draw off a little to make room for the suspension, measure out the "dose" of Bentonite, pour it into the wine through a funnel, and top up as required with wine. Re-cork, and then rotate or swirl the jar gently to mix the Bentonite into the wine. Keep it in suspension for at least 20 minutes by rocking and swirling at 3-minute intervals. Rack after a month, not before.
Egg-shells will often clear—and decolour—a white wine. Clean them, bake them in an oven—which makes them brittle—and then crush them into small pieces before adding to the wine. The tiny pieces will often rise and sink, rise and sink, for quite a long time, carrying down with them the suspended solids and thus clearing the wine, or all except the bottom quarter or so, which can be filtered.
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