"There are a great many arrangements, forms of apparatus, and processes for cleaning casks ; and cask washing and cleansing is a matter of vast importance to the brewer. But I am not at all sure that the most elaborate machines possess all the advantages claimed for them. The fact is that the washing and thorough cleaning of casks in a brewery is a matter that requires so much personal attention from the men employed" that elaborate machinery is to a great extent thrown away. In this, as in so many other instances, if a man has to watch a machine very carefully, he may just as well do the work by hand. I therefore doubt the utility of the mechanical cask washers, except in the case of large breweries.
When the dirty casks returned to the brewery are examined, they can be quickly divided into those which cannot be cleaned without one of the heads being taken out, and those which can be washed perfectly clean as they stand.
If the head is taken out of a cask, no machinery is required to clean it, and the greater number of those which do not require their heads removed, can be quickly cleansed by washing with hot water, and subsequent steaming. The mechanical cask washer, only effects a saving of labour on a small percentage of casks, which are rather too dirty to wash by hand without the removal of the heads, and are yet not foul enough to render that operation absolutely essential. In large breweries however these machines are no doubt useful and save some labour.
Every brewery should be provided with a sufficient number of cask steaming nozzles, and also with a large tank of water, kept up to the full boiling temperature by means of free steam. A blower and set of air nozzles for drying the casks after they have been washed and steamed, is also a most valuable apparatus, and one which is far too often omitted.
It is by no means necessary to heat the air which is blown into the casks to dry them, all that is essential is that the casks should be thoroughly heated by washing with boiling water, and steaming, and should then at once have a strong current of air forced through them, while the wood is at a high temperature.
There is a simple apparatus for washing casks, which is often useful, and is now much resorted to in breweries. I allude to that arrangement of pipes and cocks by which water and steam are admitted together into the casks, and the water thus boiled in them. The mechanical action obtained does, no doubt, assist in washing the casks, and there can be no objection to the use of this apparatus, provided it is not expected to do much more than supply boiling water in a convenient way. The casks, however, after they are thoroughly cleansed by means of this apparatus, supplemented as far as necessary by manual labour, must be steamed and dried, so that there is not after all much saving effected, as compared with washing the casks with boiling water from a tank.
Besides the above appliances every large brewery should have an iron pan, in which a solution of common washing soda can be boiled, for treating sour casks ; and also a tank into which the soda liquor can be emptied from the casks, for this liquor can be used over again for a good many times before it is necessary to renew it. The washing soda and water are first boiled in the pan, and the casks filled with the boiling hot liquor. After standing with the liquor in them for three or four hours, they are emptied into the tank, washed several times with clean water, steamed and dried. The liquor is pumped up again to the pan, by means of an iron rotary pump, boiled, and used for another lot of casks. When it becomes too foul for use it is run to waste.
Permanganate of potash is now largely used for curing stinking casks, and is very effectual, no special apparatus is, however, required for applying it.
For curing acid casks, in breweries which have no soda pan, quicklime is a cheap and effective substitute. It should be slaked with boiling water into a powder. One quart of this powder is generally enough for a barrel; the powder should be mixed with water, and introduced into the barrel, which is then filled with water, allowed to stand for at least twelve hours, and afterwards washed, steamed and dried.
It is a very good and safe plan to wash out all the casks with a little bisulphite of lime, after any of the above treatments with alkaline substances. The bisulphite should be applied shortly before steaming, and well rinsed round every part of the cask. All casks may be rinsed with bisulphite after they are taken off the steaming-nozzles, and before being placed on the dryingnozzles." (Source: Source: "A systematic handbook of practical brewing", by E.R. Southby, 1885, pages 152-155.)
Southby is my new favourite. He's bulking out the late 19th-century chapter of my book a treat. I'll let you into a little secret. My mega-book is becoming less of a publishing project and more of a handy reference for myself. At 165,000 words, it's getting too big for a book.