The Magic Guinness Blend c.1939

Cover of the Guinness brewing manual.

When a colleague of mine told me that her father had been head brewer at Guinness’s London brewery and wondered if I might be interested in seeing his papers, I got a bit excited.

Final­ly, months lat­er, we got round to vis­it­ing to check out what was in her col­lec­tion. Based on a quick audit the answer is: every­thing.

We’ve agreed to take pos­ses­sion of the whole lot, cat­a­logue it, copy bits we might be able to use for our own research, and then help with arrange­ments to have the impor­tant bits tak­en into appro­pri­ate archives.

For now, though, here’s a nugget from the hand­ful of doc­u­ments we brought away with us on Wednes­day night: insid­er info on how Guin­ness gained its once leg­endary com­plex­i­ty at the blend­ing stage.

This comes from a typed doc­u­ment in a plain brown wrap­per writ­ten in 1939 and updat­ed to take account of wartime brew­ing restric­tions. The copy we have seems to come from around 1943 but was in appar­ent­ly still in cir­cu­la­tion in the 1950s.

The first page bears the title ‘The Process of Brew­ing Guin­ness’ and the 46 pages that fol­low offer detailed notes on the basics of beer mak­ing (how hops are dried, for exam­ple) as well as specifics about Guin­ness.

Section header: "making up".

Here’s the sec­tion on ‘Mak­ing Up’:

Beer in stor­age vats [after fer­men­ta­tion] is quite flat and is cloudy and bit­ter and unin­ter­est­ing to taste. Before it is ready for sale it must be ‘Made up’… Beer from say six dif­fer­ent brews forms the basis. These are cho­sen in such pro­por­tions that when mixed with unfer­ment­ed beer (i.e. wort that has been pitched but not allowed to fer­ment) known as gyle, their residues added to the fer­mentable mat­ter of the gyle will give a suit­able ‘Prime’. ‘Prime’ is the fer­mentable mat­ter in beer after mak­ing up just as ‘Residue’ is the fer­mentable mat­ter as the beer enters the stor­age vat. It is mea­sured as the dif­fer­ence between the present grav­i­ty of the beer and its per­fect pri­ma­ry.

In addi­tion to these beers there are added:–

  1. Barm beer: this is the beer which is skimmed off from the skim­mers with the yeast and is sep­a­rat­ed from the yeast in a fil­ter press. It is intense­ly bit­ter but adds very mate­ri­al­ly to the flavour of the flat, unin­ter­est­ing stor­age vat beer.
  2. O.B.S.: old beer stor­age is old acid beer that, like barm beer, improves the flavour of the fin­ished beer although it is itself very unpleas­ant.
  3. Draw­ing: these are residues of made up beer which was not bright enough to put into the trade with­out fur­ther treat­ment. It is exact­ly sim­i­lar in com­po­si­tion to made up beer.
  4. Fin­ings: this is a solu­tion of isin­glass in stor­age vat beer. Only minute traces of isin­glass are required but it brings about the very rapid sed­i­men­ta­tion of all the float­ing par­ti­cles which make the beer cloudy.

All the con­stituents of the make up are pumped into a ‘Rack­ing Vat’ togeth­er and there allowed to stand for 24–48 hours.

So, there you have it. We sort of knew the gist of this but this is the most explic­it expla­na­tion of the process we’ve seen in writ­ing from a pri­ma­ry source, we think.

10 thoughts on “The Magic Guinness Blend c.1939”

  1. Very good work, and essen­tial­ly it’s the “kitchen sink” approach described by Bar­clay in the well-known, ear­ly-1800s tes­ti­mo­ny in Par­lia­ment. Guin­ness dogged­ly kept doing this into WW II.

    It’s new beer, old beer, and head­ing or unfer­ment­ed wort blend­ed to get con­di­tion and an opti­mal taste, or at least, a taste viewed as opti­mal that also had the virtue to use up every form of inven­to­ry includ­ing the bits and bobs.

    From cost account­ing to con­nois­seur­ship.


  2. For­give my vul­tur­ism but is there a pos­si­bil­i­ty any may be made avail­able for sale to pri­vate col­lec­tors?

    1. We’ll be advis­ing the own­er of the col­lec­tion against sell­ing to col­lec­tors – we’d much rather it was in an archive where every­body can access it. But of course it’s ulti­mate­ly their choice what to do with it. Feel free to email us ( and we’ll pass on the mes­sage when we report back.

      1. Thank you for your response. I ful­ly appre­ci­ate your posi­tion (and acknowl­edge it is like­ly the bet­ter answer all things con­sid­ered!). Noth­with­stand­ing, I sent an email to express my inter­est in the event the own­ers heed your cousel and decide to go in a dif­fer­ent direc­tion. In the mean­time, I am most grate­ful they did come into your pos­ses­sion and many can ben­e­fit from your knowl­edg­i­ble obser­va­tions and com­men­tary. Kudos to all.

  3. Fol­low­ing on from your recent com­ments, I would sug­gest your friend con­sid­ers donat­ing the archive to the Nation­al Brew­ing. Library at Oxford Brookes Uni­ver­si­ty rather than the LMA, as the more suit­able col­lec­tion. I would very strong­ly urge against “col­lec­tors” being allowed to get any of it, since those feck­ers sit like Smaug on what­ev­er they get hold of, and it’s lost to the world. Sim­i­lar­ly, Guin­ness is NOT, sad­ly, the best repos­i­to­ry, as they are far too secre­tive about what they hold. This is a fan­tas­tic his­tor­i­cal resource and since your friend is hap­py for the world to see it, it should be freely avail­able to the world.

    As Gary right­ly said, the descrip­tion of how Guin­ness was matured is aston­ish­ing­ly sim­i­lar to the descrip­tion giv­en by Charles Bar­clay in 1819 on how Barclay,s matured its porter, with every­thing – vat bot­toms, returned beer, left-over bot­tled stout – going into the matur­ing beer to help it long. Fas­ci­nat­ing!

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