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 riddled with shell rounds and other damage connected to 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, explains briskly:

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 film discussed by Lindsay: 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, but noted that casks from CMOS did not carry the taste. Any tannic taste CMOS did impart was easy to leach out, as William Lindsay explained in 1939, since the grain was looser than for tight American oak.

This disliked taste in American wood was, evidently, the bright vanillin and coconut flavours familiar to anyone who drinks bourbon whiskey or Chardonnay wine. And it’s not just American wine, but almost any Chardonnay as most have some storage in American oak. Of course 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 taste but to solve the problem of beer souring from microflora in hard-to-clean wood casks.

My point is two-fold: tastes change, and the coconut, vanilla taste of modern barrel-aged beer is familiar to anyone who follows the beer scene. It is doubtful the brewers knew that their British forbears (in the broad sense) generally disapproved such wood.

Even if they did know, modern brewing has set its own path. Use of American unlined oak barrels to store beer is only one example of practices now considered normal that brewers generations ago would have found odd, to say the least.*

Second point to consider: has any historical brewing recreation sought to use CMOS for a substantial part of the process? This is not say historical-object brewing using vessels made from metal or American wood lacks value. All historical recreations are approximate anyway. But using CMOS can only increase the chances of authenticity.

I’m not aware anyone has sought to do this. Some wood currently used in mashing, fermentation, or even for casks in some traditional U.K. breweries may be CMOS or English oak (similar or better according to historical sources). But even in these cases the wood in question would only influence part of the taste, probably just a small part typically.

If any recreation project has occurred, or any standard commercial brewing takes place, that does use CMOS or English wood in a substantial part of the process, I would be interested to know, certainly. In any case, I urge such a project. Memel oak is still available, in enough quantity surely to make a few casks and probably other brewing vessels.

Here is an example of the beautiful oak that helped shape British beer, and its greatness, for centuries, sourced from Ekenex JSC, a Lithuanian wood exporter, at their page here.

Note how straight are the logs, which allowed traditionally to split them for staves (no sawing). The wood was famous too for its few knots and blemishes. While not as hard perhaps as American white oak, and somewhat more porous, it was more than durable for beer cask 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…


Leave a Comment