CMOS Brewing

In 1939 with war clouds on the horizon, the Journal of the Institute of Brewing (IOB) took time to discuss a matter it had periodically dealt with in the past: the best wood for casks and a comparison of American and “Memel” oak.

The 1939 article was probably the last time the IOB looked at this, or in any detail. After the war Crown Memel Oak Staves (CMOS) from Lithuanian forests and other areas in the Baltic proved almost impossible to find. If brewers could find it, the staves were frequently marred by shell splinters and other damage from the late war.

In time, as the old Memel casks quite literally tapped out, lined American wood was relied on, with metal casks finally taking over.

Why were the American casks lined? The author of the 1939 article, William Lindsay, explained all the background:

The timber used for brewery and distillery casks is invariably oak. The origin of this oak is usually Russia or North America; other kinds have been tried but not successfully. The properties essential for cask timber are:—
(1) Neutrality—to preserve the flavour of the beer.
(2) Tightness—to prevent leakage.
(3) Breathing ability for maturing the liquor.
(4) Bending ability to prevent breakages.
(5) Hard wearing.
Russian or Polish oak has a fine balance of these properties and is shipped in staves of standardised quality and measurement. The staves are known as Crown Memel Oak Staves, and is the wood commonly used for beer casks. American oak is closer-grained and denser and consequently harder and tighter, but for that reason it is more difficult to remove objectionable flavouring matters. When used for beer, an internal lining is necessary.

[Note added Nov. 20, 2019: I later found a website with a link to the 1930s coopering film discussed in Lindsay’s article: see this post].

Hence, the casks were lined to keep out “objectionable flavouring matters”. What were they? Earlier articles in the IOB’s Journal explained them as particular flavours imparted by the species of oak typical of the Arkansas and other North American forests.

One IOB account called it a “cocoanut” taste, and noted that CMOS casks did not carry the taste. Any tannic taste from CMOS was easy to leach out, as William Lindsay explained in 1939, since the grain was looser than for American oak.

The disliked American taste was, evidently, the bright vanillin and coconut flavours familiar to anyone who knows bourbon whiskey or Chardonnay wine. And it’s not just American wine, but almost any Chardonnay, as most have some aging in American oak. (Sometimes French and other non-U.S. wood is used, but relatively little due to the scarcity and expense).

The plain fact is that British brewers did not want the American oak taste in pale ale or porter. There was an apparent exception for Guinness, as some evidence exists for its use of (charred) American oak casks in the 1800s.

But English, Scots, and Welsh brewers did not want the taste. When they first had to use American casks during WW I they lined them to keep that taste out.

British casks from CMOS were not generally lined although experiments occurred off and on since the 1800s to use enamel and other barriers. This was not to keep out a bad wood taste but to preclude souring from microflora in hard-to-clean wood casks.

Tastes change, and the coconut, vanilla taste of modern barrel-aged beer is familiar to anyone who follows the beer scene. Use of American, unlined, oak barrels to store beer is only one practice now considered normal that didn’t used to be generations ago.*

A second point to consider: has an historical brewing project been done to use Memel casks? Not that I’m aware of. Some wood currently used in mashing, fermentation, or even for casks in some traditional U.K. breweries may be CMOS, English oak, or other European. But likely the wood would only influence a small part, if any, of the taste.

And so, I urge such a project. Memel oak is available again, in enough quantity surely to make casks and probably other brewing vessels.

Below is an example of the beautiful oak that helped shape the greatness of British beer for centuries. It is from Ekenex JSC, a Lithuanian wood exporter, see their page here.

Note how straight the logs are, which allowed traditionally to split them for staves (no sawing). The wood was famous for having few knots and blemishes. While not as hard as American white oak, and somewhat more porous, it was more durable enough for beer purposes. It was “the” choice of British brewing for centuries.


*Cloudy beer is one. Sour beer is (by and large) another.



2 thoughts on “CMOS Brewing”

  1. Hi Gary ,
    Nice post , a bit of a backwater in the beer history world .
    And from what I’ve heard English oak was ,highly prized

    • Thanks Edd. As far as I know, no one has called for a recreation project that uses Memel wood or English: once again if anything has been done, I’m happy to know details.

      English oak indeed was highly prized but even around 1900 it was felt hopeless to find very much of it due to the historic cutting of the stands for HM navy and so much more…


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