Friday 10 November 2023

Mashing in the 1970s

In the first half of the 20th century, UK brewers often still had relatively complicated mashing schemes. Ones with multiple steps. Was that still the case? Let’s have a look.

From the middle of the 19th century, the classic method in London is what I call “underlet mashing”. Which is effectively a step mash.

After an initial infusion mash and short rest, a smaller quantity of hotter water was added via the underlet, that is an inlet at the bottom of the tun. The internal rakes were then spun a few times to mix this water through the bed, raising the temperature by a few degrees. This method only worked if there were internal rakes in the mash tun.

Here’s a fairly typical example form Whitbread.

1971 Whitbread Trophy and Tankard mashing scheme
action barrels strike heat time mashed time stood tap heat gravity
mash 130 155º F 10 30    
underlet 19 180º F   60 146º F 1053
sparge 1 182 165º F        
sparge 2 75 160º F     155º F 1023
Whitbread brewing record held at the London Metropolitan Archives, document number LMA/4453/D/09/141.

Just to prove that this was a common method, even amongst the big brewers, here’s another example from a Big Six brewery.

1971 Watney Red Barrel mashing Scheme
action barrels water per quarter strike heat stand
Mash 2 158º F 90
Underlet 0.1 190º F  
Sparge 1 0.5 175º F  
Sparge 2 3.5 160º F  
total water 6    
Watney Mann Quality Control Manual, page R.B. 1.

Though there is a note in the document saying that the underlet should only be performed if the initial temperature was too low.

In Scotland, where sparging was first developed, schemes had been pretty simple for more than a century. Just an infusion mash followed by a couple of sparges. It was also a scheme adopted by some regional English brewers.

For example, Boddington in Manchester.

1971 Boddington Bitter mashing scheme
action strike heat initial heat time stood tap heat
mash 150º F 142º F 75 140º F
sparge 1 162º F      
sparge 2 158º F     151º F
Boddington brewing record held at Manchester Central Library, document number M693/405/134.

The temperatures are a fair bit lower than at Whitbread. Which would make sense, as given the very high rates of attenuation at Boddington – over 90% for their draught beers – low mashing temperatures would make sense.


Anonymous said...

This may be a dumb question, but do you know why they added water by an underlet instead of just adding at the top before mixing? I'm wondering if the underlet was more complicated to plumb and more prone to clogging.

Was it something to do with temperature control or some other factor?

Ron Pattinson said...


I know 100% certain that Barclay Perkins added the water via an underlet because it says so in the brewing records. The process is also described in technical brewing literature.

It also makes sense to add the hotter water at the bottom of the mash as it would be easier to mix into the mash from there rather than the top.

Anonymous said...

Did an underlet loosen the grains more effectively and that made the raking easier compared to adding water feom the top? That seems plausible tk me, although again I don't know when you're talking about vessels on that scale.

Christoph Riedel said...

Looking at this and the boil post, how come there were several boils for some beers? In the example of Whitbread Tankard, was it the two sparges that were collected in different coppers and then boiled separately?

Truman Dark London looks wild with four boils...