CLARIFICATION—FINING.
=When Necessary.=—Wines do not always acquire the desirable state
of brightness and limpidity by repose and racking, and it becomes
necessary to clarify them. They may become cloudy through secondary
fermentations, which cause the lees once deposited to rise and become
again mixed with the liquid, or through changes of temperature, by
transportation, by careless racking, etc., and by mixing different
kinds together; or they may fail to clear naturally, because not
possessed of sufficient tannin or albumen to precipitate the
different matters held in suspension. Weak wines of poor years may
contain ferments in excess of their sugar, which may be removed by
clarification, and so fermentation be checked or retarded. Wines,
however, which are well made and properly cared for, ought to become
bright without recourse to clarification, and such will be found
preferable to, and will possess more fruitness, unctuosity, and color,
than those which have been clarified by several finings. And for
these reasons—although it may be necessary to fine such wines as do
not naturally clear themselves—care must be observed not to carry the
process too far, and deprive them of the tannin necessary to their
preservation, as well as of too much of their color, fruity flavor, and
mellowness.
=The Different Substances Employed for Clarifying= act either
chemically and mechanically, or simply mechanically. Among the latter
are blotting paper, either in sheets or in pulp, fine sand, and
powdered stone, which are placed in the cask, and which in falling,
carry down with them the matters which are held in suspension. Wine
is sometimes clarified by filtering it through woolen bags. Those
substances which act both chemically and mechanically are albumen and
gelatine, and similar substances.
=Of Gelatinous Substances=, two kinds are used, gelatine, so-called,
and isinglass, or fish glue, and they act in two ways. They are not
entirely dissolved in water; thin, transparent pellicles remain in
suspension, which form a sort of network in the wine, and in settling
they carry with them other insoluble matters. Thus, their action is
mechanical. The portion which is fully dissolved is pure gelatine, and
acts chemically. It combines with the tannin of the wine and forms an
insoluble substance, tannate of gelatine, which is readily precipitated.
=Gelatine=, so-called, is prepared from the bones, skin, and tendons
of animals, and is sold in tablets or sheets, and is sometimes chipped
or broken into small fragments. It is one of the most powerful of
finings, and causes a loss by precipitation of a considerable portion
of the tannin and of the coloring matter of the wine. It should
not, therefore, be used in clarifying red wines, except when it is
desirable to deprive them of a portion of their roughness caused by
an excess of tannin, or of a portion of their color; and it should
always be employed with caution. It produces more sediment than the
two substances next named, and leaves a bad taste in the wine, unless
perfectly fresh matters have been used in its preparation. For the
latter reason, wine clarified with it should be racked from the finings
as soon as cleared. It may be profitably used to clarify common white
wines; and if they are difficult to clarify, tannin should be added as
described below.
=Preparation.=—Take about two tablets, or one ounce, for one hundred
gallons, or double the quantity, if the greatest possible effect is
desired. Dissolve it in a dish over the fire with a little water,
constantly stirring, and do not allow the water to boil. If previously
soaked a few hours in water, it will dissolve all the more easily. Use
as directed below.
=Isinglass, Fish Glue, or Ichthyocol= (_Ichthyocolla_ of the
pharmacists), is prepared from the swimming bladder of the sturgeon,
and usually comes from Russia. It acts in the same way as gelatine,
mechanically, and also by combining with the tannin. This is
preëminently the fining for white wine. One ounce or more maybe used
for 100 gallons. It should be broken up by pounding it with a hammer
on a block of wood, and should be chopped into small fragments, so
that it may be easily dissolved. Put it in a vessel of crockery, and
pour over it of the wine to be clarified sufficient to cover it. Add
another glass or two of the wine in a few hours, when the first has
been absorbed. After about twenty-four hours it forms a jelly. This
should be thinned by adding more wine or warm water, and it should be
thoroughly worked with the hand until completely dissolved, and then be
strained through a piece of linen, using sufficient pressure to squeeze
out the mucilage. It should be thoroughly whipped or beaten, and more
wine is added if too thick. After being prepared, it may be kept for
some time in bottles, by adding a little brandy. In clarifying sweet
white wines, it is recommended that an ounce or two of cream of tartar
be added, which must first be dissolved in warm water.
=Albuminous Substances.=—Among these are mentioned the _blood of
animals_, dried or fresh, and it is a powerful clarifier. About two
quarts to 100 gallons are used, beaten up with an equal quantity of
wine. It is liable to deprive the wine of a portion of its color, and
sometimes conveys a disagreeable flavor, particularly unless used when
quite fresh. It should not be used to clarify old or fine wines, but
may be employed for new and common ones. It is of use in clarifying
white wines which have turned yellow, for it effectually removes this
color. It should be used sparingly, if at all, for red wines, and the
wine should be drawn from the finings as promptly as possible.
=Milk= is also used in the same way and in the same quantity as blood.
It is liable to sour, and a small quantity is apt to remain in the
wine. By its use sugar of milk is introduced, which is liable to
undergo lactic and butyric fermentations, and the flavor of sour milk
and rancid butter may be communicated to the wine. This may also be
used to decolor white wine which has become yellow.
=The White of Eggs= is the best of the albuminous substances used for
clarifying. It is coagulated by the alcohol and tannin, and forms a
precipitate heavier than the liquid, and as it falls, carries with
it the matters remaining in suspension. If the eggs are fresh, as
they always must be, there is no danger of communicating any foreign
flavor to the wine by their use; but it is not advisable to use the
yolks, for they injure the wine by decoloring it, and the sulphur
contained in them may communicate the odor of sulphuretted hydrogen.
This is preëminently the fining for red wine. It is also used for the
clarification of white wine, but Machard says that it is subject to be
condensed in the form of splinters (_esquilles_), which obscure rather
than clarify the liquid. The whites of ten or a dozen eggs are used for
100 gallons. They are beaten up in a small quantity of wine or water
before using.
=Clarifying Powders.=—In addition to the substances mentioned, there
are special preparations in the form of powders, sold for the purpose,
which are highly recommended by some authors. They are supposed to
consist mainly of dried blood; directions for using are given on the
package.
=Gum Arabic=, about 10 ounces to 100 gallons, is also used, but it is
not readily precipitated, and is apt to remain in dissolution in the
wine.
=Salt= is often added to the different finings, by first dissolving a
small handful in water. It renders them heavier, and as it is insoluble
in alcohol, it becomes precipitated, and thus acts in two ways. Many
authors recommend its use, but Boireau says it should only be employed
in clarifying common or very turbid wines.
=Alcohol= is added with great advantage if the wines are so weak in
spirit that the finings do not act.
=Tannin=, however, more frequently requires to be added, for upon
it and the alcohol depends the action of the substances employed.
If the wine is not lacking in alcohol, and the finings do not act,
sufficient tannin must be added to produce the desired effect. If the
ordinary tannic acid of commerce is employed, one-half to one ounce for
100 gallons may be used. Dissolve ½ lb. in a quart of the strongest
alcohol, 95°, by thoroughly shaking in a bottle of double the size.
After standing twenty-four hours it is filtered, and one gill of the
solution contains one ounce of tannic acid. This preparation of tannin,
which is prepared from nutgalls, is used for tannifying sparkling
wines, because it does not adhere to the inside of the bottle. It is
preferable, however, in general to employ the tannin derived from the
vine itself. For this purpose a strong decoction is made by steeping
grape seeds, which have not undergone fermentation, in water. They
should be coarsely broken, or bruised, and boiled for several hours. By
adding from one-fourth to one-fifth of its volume of strong alcohol of
85 per cent., it can be kept for future use. The liquor may be filtered
before adding the alcohol. Instead of the seeds, sometimes a handful
of stems are steeped, and the liquid is used. Tannified wine may be
prepared by soaking 50 or 60 lbs. of the bruised seeds in 100 gallons
of white wine, for one or two months. It is cared for as white wine.
If only one cask is to be treated, say 100 gallons, one-half pound of
grape seed may be reduced to powder and put in.
It is difficult to lay down a definite rule as to the amount of either
preparation to use, for the reason that the amount of tannin contained
in the wine itself varies. Three or four gallons of the tannified
wine are recommended for 100 gallons, and a much smaller quantity of
the first mentioned decoction would be equivalent in its effects, on
account of its additional strength. If, however, it is found that
sufficient has not been used, the wine must be clarified anew, and
tannin added again. By experimenting on a small quantity of the wine,
the proper quantity may be ascertained.
[Illustration: _Fig. 24._]
[Illustration: _Fig. 25._]
[Illustration: _Fig. 26._ Implements for stirring.]
=Method of Operation.=—After preparing the finings as described under
the head of each of the substances already mentioned, two or three
gallons of wine are drawn from the bung by the aid of a siphon, pump,
or other suitable implement, the finings are poured in, and the wine
is stirred until thoroughly mixed with them. This may be done with a
stick split at the end into three or four prongs (fig. 24), or by a
sort of brush consisting of several small bundles of bristles inserted
in a stick and at right angles to each other (fig. 25), or with a
sort of bent paddle, pierced with holes, called a whip (fig. 26). The
wine drawn out should then be replaced in the cask, which should be
completely filled, and left to rest till the wine is bright. In filling
a cask which has recently been agitated, or into which finings have
been put, a good deal of froth is frequently found which will run out
at the bung before the cask is full, and will prevent the operator from
filling it. A few smart blows on the bung stave with a bung starter
will break the bubbles and remove the foam. The time required to
clarify a cask of wine depends somewhat upon the quality of the wine
itself, and also upon the kind of finings used. The usual time is from
two weeks to a month. In no case, however, should it be allowed to
remain on the finings after it has cleared and has ceased to deposit,
for the sediment may work up again and cloud the wine, and if left too
long in contact with the deposit, the wine may acquire a disagreeable
flavor.
If, after leaving the wine a suitable time, it still remains turbid and
continues to deposit, it should be racked into a clean cask and fined
again, adding tannin, if necessary.