Clarification of these wines is effected by fining or by filtering. The best finings for the purpose are those containing albumen, such as the whites of eggs, though fresh blood may be used, but only for the commoner wines. If they are very pasty, tannin should be added, and then they should be clarified with a strong dose of gelatine.
Small quantities of wine may be filtered through paper or flannel, in closed filters.
These wines should always be allowed to rest for a while, and then be racked before shipping, for it is rare that they do not make a deposit. (See [Fining].)
Boiling Must.—Pellicot says that the common practice in making sweet wines, is to reduce the volume of the must by one-third, or even one-half, by boiling. They clear sooner, and retain less of the cooked flavor if only a part is boiled, that is, if, after boiling, one-fourth to one-third of the volume is added of must from the sweetest varieties of grapes. In this way the wines are more agreeable, and sooner matured. When the boiled must is taken from the cauldron, it must be briskly stirred with a bunch of twigs, or the like, till it ceases to smoke, in order to remove a disagreeable flavor which wines so made may contract. He gives it as his opinion that the greater part of the sweet wines, even of southern countries, are made by boiling the whole or a portion of the must, in spite of allegations to the contrary; and he considers it an innocent and legitimate operation, the only objection being the cooked flavor, which disappears with age. He excepts, however, wine made from very sweet varieties, which are ripened artificially. He also recommends that when kept in a large cask, the lees should not be removed, as they contain a good deal of sugar. As a certain quantity is drawn off, it may be filled each year with new wine of the same quality.
Sweet Muscat.—In making sweet Muscat, fermentation should be checked by the addition of alcohol, for if allowed to continue too long, the Muscat flavor will disappear. And this is usually necessary, as before stated, to keep the wines sweet.
Pressing.—Where the grapes are quite ripe, and somewhat dry, it may be difficult to extract the juice without a very powerful press; under such circumstances Machard recommends that, after crushing, the grapes be put into a vat for twenty-four or forty-eight hours, according to the temperature, and until fermentation commences, which fluidifies the must and makes it run more freely from the press.
The Marc of Sweet Wines is useful to mix with poor white wines to give them more sugar and more strength.
The amount of Alcohol to be added varies from two to five per cent., or more, depending upon the amount developed by fermentation, and the degree of sweetness desired. If the must is not allowed to ferment at all, it must be fortified up to 18 or 20 per cent.; if, however, it is so sweet that it will not ferment, it may be kept without the addition of alcohol, but it will be syrup, and not wine.
Density.—Dubief says that sweet wines should mark a density of from 4° to 5° Baumé, and the best of them even 7°.
Furmint Wine.—The following is the method given by Pellicot as practiced by him in making wine from the Furmint grape. He gathers the grapes when they are very ripe, and the small berries are half dried, and then exposes them to the rays of the sun for six or eight days, upon screens. When ready to crush, he takes the screens to the crusher. The dryest berries are then removed by shaking the frame, or with the hand, and put by themselves; and the remainder are crushed in the usual manner. Then the dry ones are crushed as well as possible, and the two kinds are mixed together and fermented. Owing to the syrupy nature of the must, it ferments for a long time, and without much effervescence. When it acquires a suitable flavor, it is drawn off, and is then racked several times till clear.