Flatness in the Cask, as we will call it for want of a better term, Boireau says, consists in the disengagement of carbonic acid gas which is produced in the interior, and is generally found in casks which have been bunged up without washing, and which gives them an odor of stagnant lees with slight acidity, and will extinguish the sulphur match. After the bad air has been expelled the cask should be well washed with the use of the chain. A cask which has contained wine that has become flat should receive the same treatment. If a large tun is to be treated, the foul air should be expelled, and a man should not enter till a light will burn in it. (See the disease, [Flatness].)
Acidity will be found in the cask if it is left for several days uncared for; the alcohol contained in the wine remaining on the inside of the cask acidifies in contact with the oxygen of the air, and is soon changed into acetic acid, and the change is much more rapid in a high temperature. Instead of being simply flat, the cask is now really sour, and smells of vinegar. The treatment consists in either removing or neutralizing the acid. The first can be done by steam. Turn the bung-hole down, and conduct a jet of steam into the cask either through the faucet-hole or the bung; the water condensed from the steam charged with acid runs out at the bung-hole, and the process must be continued till the water no longer has an acid flavor.
Where it is not convenient to use steam, rinse the cask by using the chain, and scald it out with hot lye made from wood ashes or potash, or with quicklime dissolved in hot water. Give it several rinsings with the alkaline solution without allowing it to cool, and, if possible, fill it with cold water and let it soak three or four days, and rinse as usual. If the water is allowed to remain longer in the cask it may become stagnant.
Mouldy Casks.—Casks may become mouldy inside when left in a damp place, if the bungs are left out, or if they are leaky through defective staves or hoops, sometimes even when they have been sulphured, and much more if they have not been. This condition is recognized by a mouldy smell. The surest way to treat a mouldy cask is to take out the head, and give it a thorough scrubbing with a stiff broom and water. If after removing the mould the staves resume the color of wine-stained wood, it is proof that the wood has not been affected, and the head may be replaced, and the cask rinsed in the usual way. If, however, after removing the mould, the wood is found to be of a brown color, it is more or less rotten.
Rottenness is due to the same causes as mouldiness, and when the inside of a cask is decayed, it is no longer fit for wine. If, however, the mouldy cask is brown only in spots, they should be entirely scraped off, and then it may be used. But it is best not to put good wine into such casks, for there is danger of spoiling it.
Brandy Casks, when emptied, should simply be bunged up, without washing, as the alcohol remaining will have a preservative effect. They should not be kept in a place which is too damp.
Do not Sulphur Old Brandy or Whisky Casks which have recently been emptied or in which any alcohol remains, or you may cause a disastrous explosion. In preparing new casks for the reception of brandy, they should be washed and left to drain for twenty-four hours and until they are dry, and if they are to be kept some time, throw in a glass or two of brandy, bung tightly, and roll and shake till the inside is moistened with the liquor. If they are to be used at once, they ought to be first soaked with water for three or four days to remove the woody taste.
Boireau says that common wines may be put into brandy barrels, or even oil barrels which have not become rancid (olive oil barrels, I presume), but that fine wines should never be put into them. He also adds that wine should not be put into casks which have been used for rum, kirsch, vinegar, absinthe, vermouth, or any other liquor having a strong odor, traces of which will be preserved in the pores of the wood, even after the staves have been scraped.
Cask Borers.—There is a beetle which is very destructive of casks in California, which Mr. J. J. Rivers, curator of the museum of the University, describes as Sinoxlylon declive of the family of Bostrichidae. In a paper read before the Anthrozoic Club, and reported in the Rural Press, Vol. XX, p. 153, 1880, he states that at the request of Mr. Schram, of Napa county, he experimented with the insect in order to ascertain a remedy for the ruin caused by it. He says that “Its primary mischief is caused by the habit of the parent insect boring a hole three or more inches for the purpose of depositing eggs. As casks are usually much less than three inches in thickness, the beetle taps the liquid contents, and loss accrues by leakage. The remedy I first thought of was to select some species of wood suitable for cask making that would be unpalatable to this insect. My endeavors in that way have resulted in failure for the reason that this beetle appears to have no particular dislike to oak, chesnut, pine, whitewood, and several of the eucalypti. The next step was to saturate the outside of the cask with a strong solution of alum water applied hot, and when dry, a coat of linseed oil, this latter to prevent the alum from being washed out, as it would be in time. This proved a success, for all the examples treated with the solution were untouched, while the unprepared were riddled by the borer.” The insect is more destructive to casks stored in light places; it is therefore better to keep them in the dark.
The Size of the Casks is a matter of a good deal of importance. For shipping, the ordinary pipe or puncheon holding from 150 to 200 gallons is of a convenient size for handling, but for storing it is better to use as large a vessel as possible, and where the quantity stored is large, tuns of from 1000 to 3000 gallons or more in size are far preferable. In the first place, it is a well known fact that wine made at the same time, of grapes of like varieties, from the same vineyard, and under the same apparent conditions, turns out quite differently in different casks, and the contents of one cask may far excel in quality that of another. In order to insure uniformity in a large quantity of wine, it is necessary to store it in large receptacles.