A Modern Lager Brewery - Lagering

We've reached one of the most fun bits of the process: lagering.

It's fascinating to see how the author describes some of it, using terms that a UK brewer would feel comfortable with.

"Lagering or Storing.—The lager cellars are usually arranged to open on to a long corridor, the temperature of each being independently adjusted (where ice machinery exists) to suit the variety and condition of the beer with which it is filled. In order to ensure perfect uniformity, the produce of several brewings will be blended by being distributed over all the casks in a section. The following particulars (see opposite page) of the filling of such a cellar, and the procedure during the lagering will illustrate how the work is carried out.

During lagering a slow complementary or deferred primary fermentation takes place, during which the beer, in a measure, cleanses itself through the bunghole, but mainly by the deposition of the yeast and amorphous matters. In order to provide a surface of attachment for the latter, since the insides of all these store casks are coated with pitch, quantities of hazel or beech strips, as exhibited, are employed, these being either laid in the bottom before filling or added afterwards. As the casks are emptied these strips are romoved, and after a thorough washing in a special machine and subsequent sterilisation, are used again. When the beer has sufficiently matured and cleansed itself, it is bunged tight and the bunging apparatus so adjusted that a pressure of about 0.4 of an atmosphere of carbonic acid is generated in the cask. The period when bungitig down and when the beer will be ready for sale will depend on the condition in which it left the fermenting vessel, the time allowed for the beer to cleanse itself, and the temperature of

Cellar No. 6 in Long Corridor. Temperature 2R. = 36.5º F.

Brew Nos.	Dates.	No. of F.Vs. at 27 hectol.= 16.5 barrels.
875/6	18/8	2
875	19/8	2
879	21/8	4
884	22/8	8
885	23/8	1
886	23/8	1
887	24/8	8
888	24/8	7
888	25/8	1
889	25/8	1
891	26/8	7
891	27/8	1
892	27/8	4
892	28/8	4
894	29/8	1
895	29/8	7
895	30/8	5
896	30/8	8
898	30/8	1
899	31/8	8
900	31/8	1
		79 = 1,308.5 barrels.

Topped up on 6/10—17/10.

1st row bunged 26/10.	5th row bunged 30/10.
2nd „ „ 27/10.	6th „ „ 1/11.
8rd „ „ 28/10.	1st row racked 16/11.
4th „ „ 29/10.	1st four rows empty 1/12.

the cellar; the cleaner the beer was at casking and the older it was at bunging, the longer will it take to come into condition. Young beers, as they are called, may be rapidly brought into condition by the addition of Kräusen, but if treated in this way, they must meet with a quick sale. Exigencies of modern trading have rendered quicker methods of finishing necessary in some cases, but the best characteristics of a true lager are only developed by reasonably lengthy storage at low temperature and without any fictitious aids to accelerate the process, as are so common in America. The modern method of racking lager is to pass it by means of a pressure-regulating pump through a filter to the counter-pressure filling machine."
Journal of the Institute of Brewing, vol. XVII, 1920, pages 496 - 498.

 It's the first time I've seen the recommendation to mix batches in the lagering vessels. Though I can see that makes sense if consistency is your goal.

The way lagering is described is in very British terms: "a slow complementary or deferred primary fermentation". Why not use the term secondary fermentation? Because in British brewing parlance that's reserved for a Brettanomyces fermentation. As only Saccharomyces is involved here, the term isn't appropriate.

In the very same sentence, cleansing is mentioned. That's the processs of removing unwanted material - mostly yeast - from beer. Victorian brewers were obsessed with it and employed various methods to achieve it. The most famous being Burton unions. It drives me nuts when I see them referred to as fermenting vessel. They weren't. It's where the beer went after being in fermenting vessels.

Beechwood, of course, is what's used in the production of Budweiser. Bunging is the old-fashioned way to carbonate Lager. If done correctly, there's no need to forse carbonate. I was shocked to discover that in the early 1960's Harp Lager was carbonated this way.

Not sure why you'd need to sell a beer that had been Kräusened quickly. Was it less stable?