CASKS.
Seasoning new Casks for Use.
As new oak staves contain a considerable quantity of gallic acid and tannin (tannic acid), it is advisable to remove these acids from new casks, lest they should impart a disagreeable flavour to any beer with which they may be at first filled. Many methods have been resorted to for seasoning, as it is technically called; but after having tried most of them, we have found that the best and most certain way is to neutralise the acid by means of an alkali; and for that purpose a solution of quick lime in warm water will be found perfectly efficient. Fill the casks with boiling water, into which introduce about 1 lb. of quick or unslacked lime in powder, which is more than the water can dissolve; then immediately bung the casks close, and roll them about. Let this mixture remain in the casks two or three days, rolling them about occasionally. The casks may then be emptied, and the lime be carefully washed out with several changes of boiling water, after which the casks may be safely filled with beer. To those who choose to incur that expense, sub-carbonate of soda or potash may be used, perhaps rather more effectually; but we think that quick lime, which, being cheaper, can be more easily obtained at all times, will be found sufficient for the purpose.
A woody flavour is sometimes given to casks, and is said to be derived from the firing of the cask by the coopers. All such casks should be well grouted after the firing, before being filled with beer.
Cleaning Musty or Stinking Casks.
When too much fire is applied in making up casks, it raises blisters in the interior of them. These blisters, if not removed, very soon produce mustiness from the filth which gathers under them. They should, therefore, be all cut out with the cooper’s iron, and until this is done, the casks cannot be effectually sweetened. A solution of chloride of lime (bleaching powder) in boiling water will then have the desired effect. Put about twenty or thirty gallons of boiling water into a butt, or less in proportion for smaller casks; then throw in a few ounces of chloride of lime, according to the size or the cask, and then pour in an ounce of muriatic acid (spirit of salt mixed with water) to evolve the chlorine gas rapidly. Bung the casks closely as soon as possible, to prevent the escape of the chlorine gas. Roll the casks about, when the gas, by penetrating the pores of the wood, will very soon remove all remains of mustiness.
Tainted vats or backs are rendered sweet, and fit for use by washing with diluted sulphuric acid, and afterwards with lime water, and then pure water.
In the London porter breweries all the butts and other casks, if long kept and not sweet when returned, as from the country, are steamed, after being washed with boiling water. After the steaming, in which the force of the steam is considerable, they are again washed with hot water.
It is a curious fact, that musty beer is generally bright: this circumstance is not easily accounted for.