hist-brewing: oak and beer

Kirsty Pollock kirsty.pollock at mpuk.com
Thu Sep 30 01:20:53 PDT 1999

>From the UK Homebrewing site
The most relvant summary passage is the last para.

Wooden Casks
The following extract is directly transcribed from H.E Wright's treatise on
brewing (see sources cited at the end of this document). All emphasis is
that of the original:
"Casks are made of foreign (Memel) oak, as a rule. The timber should be free
from worm-holes and sap. It comes to hand in lengths (balk or juggle) of
rather over six feet, and of a thickness which admits of three stave lengths
being got. Foreign oak, being straighter in the grain than English, admits
of being split; English has to be sawn. Moreover, the latter warps when
Barrel staves are 31 inches in length; kilderkin staves 25 inches, and care
should be taken to divide the timber lengths so as to avoid waste. The
pieces of which the heads are made are joined together by dowel pins (wooden
pegs) and bevelled round, so as to fit into the croze grooves. The chamfered
edges (afterwards painted) form the chime. The hoops of hogsheads and
barrels are known as the end, bulge, and quarter hoops respectively;
kilderkins (generally*) and firkins only have end and bulge hoops. Casks are
classed as stout, intermediate, or slight, according to the thickness of the
staves. The thickness of the heads and width of hoops also vary. 
The thickness of the staves runs as follows. 
                Stout.          Intermediate.   Slight.
                inches          inches          inch.
Hogsheads       1 1/2           1 1/4           1
Barrels         1 1/2           1 1/8           1
Kilderkins      1 1/4           1 1/8           1
Firkins         1 1/4           1 1/8           1
* Slight kilderkins, however are hooped with six hoops, like barrels." 
After some discussion on the appropriate wages for coopers, Wright moves on
to the treatment of new casks. This section is worth repeating in full in
light of the often made assumption that casks imparted an oak flavour to the
beer, which has led to many people incorporating oak chips into IPAs. Note
that in his description of cask making, Wright does not mention lining the
casks. This is a relatively modern phenomenom which has to do with
cleanliness and not impartation of flavour. (Further discussion on lining
casks can be found at the end of this section). 
"To Season New Casks - Fill them with very hot liquor or salt. Most of the
colouring matter and woody flavour will be extracted in thirty-six hours.
Fill, however, for the first time, with black beer. 
For pronounced "stinkers" there is supposed to be no cure, but the chloride
of lime whitewash treatment, succeeded by muriatic acid and bi-sulphite
successively, each being driven in by steam, might certainly be tried. 
For moderate cases a foreign journal suggested treatment with strong
solution of bi-carbonate of soda till it soaks into the pores. Then, after
draining and rinsing, water acidulated with HCl is added, the evolved CO2
being supposed to drive out putrescent matter. The use of permanganate of
potash has also met with some success." 
It is also worth quoting a few of his words on cask-washing:
"Cask-washing Machines - The simplest form of effective arrangement for
cask-washing (apart from taking out the heads of and hand-scrubbing each
cask) is to have a series of nozzles, through which, by duplicate cocks,
either steam or boiling water can be delivered. A modification is the
Pontifex apparatus, where steam and water are admitted in a similar way, the
water being boiled on its way, or within the cask. 
Other machines have been designed to give a thorough revolving motion in all
directions to the cask, which is charged with a few pebbles as well as half
filled with boiling water. The most elaborate of these, which has not yet
been surpassed, is the patent by Robinson of Bridgewater." 
There is also an interesting discussion of wooden casks by Sykes and Ling in
The Principles and Practice of Brewing, 1907, which is quoted in full here: 
"The large vats for storing purposes are made of the best English oak,
hooped with iron. Since they are subject to the attacks of a fungus which
causes dry rot, they should be examined periodically, and measures for the
eradication of the fungus taken as soon as its presence is detected. 
The trade casks are generally made of foreign oak, occasionally of English.
The best quality of foreign oak comes from Memel, the next best from
Dantzic, other kinds from Odessa, Blumeza, and Riga. Ale casks have been
constructed from time immemorial of wood, which is a substance of a porous
nature, into the interstices of which bacterial and other minute organisms
are extremely liable to effect an entrance. When certain species of these
organisms have, in this way, invaded the substance of the wood, it is next
to impossible to effect their removal. A cask so attacked is known as a
"stinker," in which condition it is completely useless for the carriage of
beer. On the Continent the casks are coated internally with a peculiar kind
of pitch, so that the beer never comes into contact with the wood. Probably
in the future some material which does not take up impurities so readily as
wood will be employed in the construction of brewery casks, such as steel
lined with tin, or wood with a lining of some indifferent metal." 
So the conculsion from these two contemporary reports is that casks were
made in the main from Memel oak, they were unlined (except in Continental
Europe where they were lined with pitch), and they did not impart any oak
flavour to the beer they contained. Thus the addition of oak chips or any
form of oak flavouring to English styles of beers does not conform to the
true style. 

Sources Cited:
A Handy Book for Brewers being a Practical Guide to the Art of Brewing and
Malting, Embracing the Conclusions of Modern Research which Bear Upon the
Practice of Brewing, (pp 499-501) by H.E. Wright. Published by Crosby,
Lockwood and Son, London. 2nd edition. 1897. 

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