What is the dropping syste.

 I explain the dropping system of fermentation.

 

Fullers boiling and fermentation in 1910

Processes now. Starting with boiling and fermentation.

With the exception of X and BO, all the beers had two coppers.

Nothing very odd about the boiling process. Mostly, the boil length was in the range of 1.5 to 2 hours. Which was fairly typical. The only exception is BO, where the boil lasted 2.75 hours. Presumably some of that time was to concentrate the wort.

The fermentation temperatures are equally unexceptional, in the 60º F to 70º F range. I’m not finding much to say here, am I? 

Around a week for primary fermentation was pretty standard, too. Fullers used the dropping system of fermentation. I thought it would be interesting to include when the beers were dropped to the settling square.  There doesn’t seem to be much consistency to it, varying between 20 and 70 hours. 

Fullers boiling and fermentation in 1910
Beer	Style	boil time (hours)		Pitch temp	max. fermen-tation temp	length of fermen-tation (days)	dropped after (hours)
X	Mild	2		59º F	69º F	7	20
AK	Pale Ale	1.75	2	60º F	68.5º F	8	70
PA	Pale Ale	1.75	2	59.5º F	69º F	8	46
P	Porter	1.5	1.75	60º F	66.5º F	6
BS	Stout	1.5	1.75	59.5º F	69º F	6
BO	Strong Ale	2.75		60º F	70º F	9	60
	Average	1.88	1.88	59.7º F	68.7º F	7.3	49.0
Source:
Fullers brewing record held at the brewery.

 

Cleansing vessels.

Something that annoys me - among many, many other things -  is when Burton unions are described as fermenting vessels. They aren't. They're cleansing vessels. The fermentation started in rounds or squares and the wort was only later moved to the unions to, primarily, remove excess yeast.

It wasn't the only system or cleansing. Pontoes were an older system, with unions really being a more sophisticated and automated, development of it.

Cleansing vessels.
Where the fermentation was completed and excess yeast removed. There were three types of cleansing vessels: pontoes, unions and settling tanks or squares. Pontoes were single barrels, placed on stillions into which yeast was expelled through the bung hole. The casks were kept full by refilling, by hand, with wort which had been expelled with the yeast. Unions were similar, but a series of casks were connected together in a "union", pipes being so arranged as to automatically return expelled beer to the casks without the need for manual refilling. 

Watney's pontoes in 1902

Settling tanks were quite different. They were shallow tanks, placed beneath the gyle tuns into which the wort was dropped after between 12 and 24 hours. Rather than being expelled from a barrel by the action of fermentation, yeast was removed by a combination of skimming the head and allowing it to settle to the bottom. It was also known as the "skimming system" for this reason. It was also known as the dropping system. It was used by some of the large London breweries. Fullers used this method until the 1970's. Brakspear's beers were fermented this way until quite recently. Fitted with attemperators, when the final gravity had been reached, the beer was slowly cooled over a few days to a temperature of around 60º F before racking.

"Unions are noted for the clean tasted beers they give; pontoes are most fitted for porter and stouts, while a skimming system is specially adapted for stock beers."
"The Art of Brewing" by Frank Faulkner, 1876, page 139.

Quite impressive that Watney ponto room I wonder when the last ponto system was removed?

The above couple of paragraphs come from one o my many unpublished manuscripts. Namely. "Beer, Ale and Malt Liquor". A history of UK brewing from 1700 to 1973.

There's a funny story about how I wrote it. In the second half of my programming career, I had several contracts where I had little to no work. At one*, there wasn't even internet. Out of sheer boredom, I loaded pdfs of old brewing manuals onto a memory stick and took it into work. Where I spent the day trawling through them and knocking up text/notes for my mega book.

I've used bits of it over the years. For reference. Or for low-effort blog posts, like this one If all has gone well, I'll be in Montevideo with the kids 

Note sure where I'm going with this. Hi from Uruguay. (Where, unless I die in Brazil or Chile, that where's I'll be when this is published.)

 

 

* We had so little work, that when something came in half a dozen of us would huddle around the terminal watching the lucky chap who got to start the job. For 8 hours, 59 minutes each day, I had nothing work-related to do.

Best thing was, every Friday, someone went to a fish shop and got, er, fish for the office. Broodje kibbeling (fried fish nuggets in a bun) was always my order. So much so, I continued the tradition for 10 years in my next, and last, job.

Dropping fermentation

A two-stage fermentation, where the process kicked off in a tall cylindrical vessel then the wort was “dropped” to a shallow square vessel, remained fairly popular in the South of England.

There seems to have been quite a bit of variation in exactly how long elapsed between pitching and dropping. At some breweries, such as Fullers and Adnams, the wort remained no more than 12 hours in the upper round.  At others, it could stay there for two or three days.

Fullers brewing logs recorded the fermentation process in some detail:

5th November 1941 Fullers X Ale fermentation
day and time	temperature	OG	action
Wednesday   18:00	63º F	1028.6	pitched
Thursday      03:00			dropped
15:00	64º F	1022.8
22:00	65.5º F	1019.2
Friday         6:30			lowered sluices
08:00	68º F	1013.3
14:30			collected and pumped
15:00	68º F	1010.8
20:00	68º F	1008.9
Saturday           8:00	67.5º F	1007.8
12:00	67º F	1007.5
20:00	66.5º F	1007.5
Sunday             9:00			liquor on
Tuesday           4:30	59º F		racked
Source:
Fullers brewing record held at the brewery.

The fermenting wort was only briefly in the upper round – a mere 9 hours – before being dropped. “Collected” refers to yeast being skimmed off the top for repitching. While “liquor on” is the attemperator being activated.

All in all, the fermentation took around 12 hours short of a full week. Which seems quite a long time for a beer of such a modest gravity.

Fermentation after WW II

In the immediate aftermath of WW II, most breweries still employed open fermenters. Either round or rectangular in shape. By this time they were usually constructed of metal or were at least metal lined.

Fermenters were fitted with attemperators – a series of metal pipes through which cold brine was passed. This was one of the huge innovations of the late 18th-century, allowing brewers to precisely control the fermentation temperature. It led to improved beer quality and the possibility to brew year round.

Many of the older systems of fermentation/cleansing were still in use.

Dropping System
Common in the South of England, in the dropping system two vessels were employed. The wort started fermentation in a tall, round fermenter and after a certain length of time – which could vary between 12 hours and 2 or 3 days, depending on the brewery – was dropped into a lower, shallow, square vessel.

The idea was to remove much of the yeast, which was either left in the upper round or quickly settled out in the lower square. This vessel was often called a “settling square”. The transfer between the two vessels also aerated the wort and reinvigorated the fermentation.

Yorkshire Square
As the name implies, this was popular in Yorkshire, but it was also extensively employed in the Midlands. There was a main square, usually made from slate but sometimes of metal, above which there was a second chamber. The fermenting wort was pumped to the upper chamber and then allowed to drain back down, leaving most of the yeast behind.

As with the dropping system, main purposes were to remove surplus yeast and to aerate the wort. Yeast used to operating in a Yorkshire square often struggles in a standard fermenter due to not being sufficiently roused.

There are still several breweries in the UK that employ this sort of fermenter.

Burton Union
This system was once common across the UK for brewing Pale Ales and wasn’t just limited to Burton. It is not, as people today seem to think, a fermentation vessel, but a cleansing vessel. Fermentation began in a conventional open round or square and the wort was only transferred to a union after a couple of days.

A union set is a series of linked casks. In the bung-hole of each cask there’s a swan-necked pipe through which yeast-laden wort rises and spills into a trough. The trough channels the wort back into the casks leaving the yeast behind. As with the other systems described above, it’s mostly about cleansing, that is removing yeast.


The above is an excerpt from my overly detailed look at post-war UK brewing, Austerity!

http://www.lulu.com/content/paperback-book/austerity/23181344

Which is now also available in Kindle format.

Ale brewing in the USA and Canada in 1907 (part four)

As promised, this time we're going to look at the Wittemann process in detail.

It was named after the firm which produced the equipment, the Wittemann Company. I was surprised to discover that they're still making CO2 recovery systems. Though they are no longer an independent company, having been bought by the Danish firm Union Engineering A/S on 1st April 2013. Oddly, their website states the process was first developed in 1912, five years after this article was written.

This is a brief description of how the system worked:

"No doubt, most of the gentlemen here are familiar with what is known as the Wittemann process. There is nothing particularly novel in the process itself, but it is for the special plant and appliances for carrying out the system of gas collection and reabsorption by the beer that the firm lay claim to, and I believe they are perfectly justified in their contention, from what I have seen of the plant.

When in New York I called on Mr. Wittemann, who gave me an introduction to the proprietors of a large ale brewery where their plant could be seen in full work.

As Mr. Wittemann explained, there are numerous ways of adapting or using their plant to suit the requirements of the respective users. Therefore, I shall just explain the working of this plant as I saw it in this particular brewery."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 363.

And here's the detail of what they did at this particular Ale brewery:

"They pitched their worts in open vats, just in the same way as we do. In about 36-48 hours after pitching, or when the fermentation has got a good hold and is giving off gas freely, a portion of the wort is run off to a closed-in vat (of which they had several). They only ran enough into these closed-in vats that was required to give them enough CO2 for carbonating purposes.

These vats were filled almost full, and were fitted with a 0.75-inch vent pipe on the top, through which the remaining air was expelled as the gas collected in the space at the top of the vat. The vent pipe was left open until the brewer considered what was the right time to start pumping the gas off. This he determined by the aroma or smell of the escaping gas.

The brewer assured me that the time when the gas was collected from the fermentations was the all-important part of the whole business.

When the right moment had arrived the vent pipe was closed and pumping commenced, and continued for 12-18 hours as the ease may be, when they would go on with another vat, and so on, until they had as much as required, or that the steel storage tanks were full.

It is at this pumping stage that the special plant manufactured by the Wittemann Company plays an important part.

The gas during pumping and compression is kept as cool as possible, so as not to destroy any of the natural aroma or ethers contained in the CO2, and to facilitate that the storage cylinders are large, and the pressure not allowed to exceed 200 lb. to the square inch.

The beer, after having the gas collected from it, is run along with the other fermenting beer to dropping vessels to finish."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, pages 363 - 364.

Is that clear? Most of the beer still underwent an open fermentation and only a small amount went into the special Wittemann vessels. It's interesting that they wanted to retain more than just the pure CO2. Did they really retain the natural aroma?

Even more fascinating is that this brewery was using the dropping system. It seems to have been reasonably common in North America. I'm quite surprised by that. I wonder if any breweries had union sets?

The advantage of the system was the time it took to ferment beer was much shorter:

"The fermentations at this brewery were far quicker than the others, for in six days from pitching the beer was run direct from the fermenting vats to a quick chilling machine, and afterwards through the special type of saturator or carbonator, when it was saturated with its own natural CO2 and finally filtered brilliant and racked or bottled as required.

Broadly speaking, in eight days from pitching, the beer was on the market.

There was no storage in cold cellars. This fact alone means a great saving in the locking up of capital, also in capital outlay for the building and equipment and the maintaining of large cold storage cellars. But still, in my opinion, that was at the expense of the quality of the product."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 364.

Being able to sell beer just eight days after pitching is impressive. That's about the same time as it takes to produce Mild. But here's the most important question: how did the beer taste?

"The process is very quick, and moderate storage would probably have given a better beer.

The beer did not impress me. When sampled it had a very new, soft, soapy taste, but a very nice and pleasant aroma, the latter due, no doubt, to the fact that it had been carbonated with natural CO2. There was a marked difference between the draught and the bottled beer. Although it was the same beer in cask and bottle, the draught ale was by far the better of the two. The inferior flavour of the bottled beer I put down to the effects of pasteurising, although I had not noticed such a marked difference in the other brewers' bottled beer which had gone through the process of pasteurising.

I may say here that it is the rule to pasteurise the bottle goods at all the breweries, either ale or lager, both in Canada and the States. Although it enhances the keeping properties, it certainly deteriorates the flavour."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 364.

The answer: not that great. Especially after being pasteurised. You can tell the author wasn't a fan of pasteurisation. I think the methods they used in the early days of the process "cooked" the beer more and were more injurious to its flavour than those of today. Still not a huge fan of it myself.

That difference between bottled and draught beer - the former pasteurised, the latter not - was true all through the 20th century, and is still the case with American industrial breweries. Though there have been odd examples of unpasteurised bottled beer, such as Miller Genuine Draft.

Ale brewing in the USA and Canada in 1907 (part two)

More fun with brewing in Edwardian North America.

First a good example of the way brewing is shaped by legislation and taxation.

"The brewing operations in the States and Canada differ somewhat, owing to the fact that the American has, to a certain extent, a free mash-tun, and consequently uses a large percentage of raw grain, but no sugar. The duty is levied on the finished beer at the rate of 1 dol. per barrel of 31 gallons, and is collected by the issuing of stamps, which are pasted over the tap hole of the casks.

Owing to a large percentage of raw grain used, a low primary initial goods heat is aimed for, which is quickly raised by adding the contents of the converter to the mash. It is not the practice to stand the mash as long as we do. Sparging is commenced about an hour after mashing, and continued until all the extract is washed out.

The Canadian brewers, on the other hand, use nothing but malt, on which the duty is levied at the rate of 1.5 cents per pound; the system being very similar to what obtained in England prior to Mr. Gladstone's Beer Duty Act of 1880. The brewing operation, therefore, is very much like our own as regards mash-tun treatment. They all use the closed-in, steam-jacketed boiling coppers or kettles, as they term them."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 360.

It's odd that both the USA and Canada were using old British systems of taxation. The American flat rate beer barrel was very much like that used in British system from before 1830, except that in Britain there were two rates, one for Table Beer and another for Strong Beer. Whereas the Canadian system was like that used in Britain between 1830 and 1880, when there was no tax on beer itself, but instead the ingredients were taxed.

This is a difference in equipment that I've not heard mentioned before:

"From the hop back, the wort goes direct to the refrigerators. Coolers, as we know them, with all their attendant evils, are not used either in ale or lager breweries. I think brewers in our own country are now dispensing with what was at one time thought to be an indispensable portion of brewery plant."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 360.

How ironic that some American breweries are now installing coolers just to get their beers innoculated with wild yeast. British brewers from a century ago would have though them crazy.

"The ale is pitched in the usual way, but with a very small amount of yeast. This rarely exceeds 0.5 lb. per barrel, consequently the fermentations proceed very slowly for the first 48 hours. They then begin to make up for lost time, and one cannot but notice the healthy state of the fermentations. They carry good heads, and throw up a great quantity of strong, sweet-smelling yeast. The dropping system is used to a great extent.

In most of the breweries a small cold store is used for keeping the store yeast, as it behoves the American and Canadian brewer to keep the yeast as pure as possible and free from contamination."
Journal of the Institute of Brewing, Volume 13, Issue 4, July-August 1907, page 360.

Now isn't that interesting: they used the dropping system for primary fermentation. Not sure I've ever heard of it being used outside Britain before,

Just checked on some pitching rates. In this period, Whitbread pitched far more than half a pound per barrel:

Pitching rates at Whitbread in 1908
Beer	lbs yeast	OG
IPA	1.1	1049.5
FA	1.1	1050.0
X	1.2	1054.2
2PA	1.4	1054.2
PA	2	1063.7
KK	1.7	1074.2
2KKK	2	1078.7
KKK	2.2	1084.5
Source:
Whitbread brewing record held at the London Metropolitan Archives, document number LMA/4453/D/01/073

As you can see, the stronger the wort, the more yeast that was pitched.

Next time we'll be looking at what happened after primary fermentation.

Homebrew dropping fermentation

Anyone ever done a dropping fermentation at home? If you have, get in touch.

A Dropping Problem.

British brewershad some adjusting to do after WW I. It took them a while to get the hang of brewing low-gravity beers.

During the 1920's and 1930's brewers acquired new skills. They learned how to tweak recipes and techniques to compensate for the lower strength. Britain's brewers became masters of producing stable, flavoursome beers of modest gravity. It's something they still excell in today. Where else are beers of less than 4% ABV brewed that actually taste of something?

This is an example of brewers adapting to the new circumstances. It concerns the dropping system of fermentation, which used to be common, especially in th South. Fermentation started in tall round vessels and then transferred (dropped) into shallow square vessels. It helped aerate the wort and stop the remperature of the wort rising too much. It also aided clarity, as much sediment was left in the round.

"A Dropping Problem.
It is customary, in dropping equate breweries, to drop or cleanse the fermenting worts at or about the period of half-gravity. This procedure answered well enough when gravities were liberal, but since the compulsory advent of weak beers, some few workers have found that if allowing fermentation to proceed to the limit of half-gravity before dropping to shallow skimmers, the necessary increment in heat does not always take place during the colder months of the year, with the result that the fermentation receives a more or less severe check which is apt to leave its imprint on the finished beer. Limited depth of wort and aeration at dropping are naturally conducive to increased reproductive activity and a corresponding tendency for yeast to rise to the surface before full attenuation and purging of the fermenting fluid is accomplished. No great harm may come of this while the weather remains cold, but matters should certainly be adjusted before the advent of summer, since high racking finals coupled with insufficient purging of wort are certain forerunners of disaster under anything like forcing conditions of temperature, The matter is a simple one and essentially practical, and by restricting the temperature in the collecting vessel and arranging to drop the worts at an earlier period, normal and sufficiently extended attenuation usually results, assuming, of course, that materials and procedure are in order."
Brewers' Journal 1921, Page 115.

Seems to make sense. A weaker beer need to be dropped earlier.

As I have brewing records from breweries using the dopping system that span WW I, it was easy enough to check if they changed when they dropped.

I looked at Fullers first, as I've a good set of their records. Except they never let the wort get anywhere near half gravity. They usually dropped after around 12 hours, so nowhere near half gravity. Both before and after WW I. I could see no change.

Next I tried Kidd. Their records have a full fermentation record and indicate when dropping occurred. This is what I found.

This is a batch of X brewed 5th April 1917:

And this is one brewed on the 25th February 1936:

As they'd switched from brewer's pounds to specific gravity, I'll convert the first lot to SG: 15.4 is  1042.7º and 9.4 is 1026º. Mmm. The 1917 brew was dropped when the gravity was 61% of the OG. So well above half gravity. The 1936 brew was dropped when the gravity was 42% of the OG. Or well below half gravity.

The same story is repeated for all Kidd's beers. In the 1930's they were waiting longer before dropping than they did in 1917. The exact opposite of what the article says. Isn't that confusing?

Aitken's Old Brewery (part two)

We're back in the old-ish Aitken's brewery. Though as you read the passage below you'll realise that it had already been greatly altered and enlarged.

The original brewery was all on the south side of Newmarket street. But during the 19th century a new, much larger set of buildings had been added on the north side. These wren't concerned with brewing, boiling or fermenting, but were ancillary buildings such as stores.

"Retracing our steps, we came to the mashing-stage, 40 feet square, situated in the centre of the brewhouse. Here we were shown two mashtuns, constructed entirely of copper, and commanded by a Steel's mashing machine. They both contain gun-metal draining-plates, and each is capable of mashing twenty quarters of malt. The underbacks are below the tuns, from which the wort is pumped up direct to the coppers. We have previously written so much on the nature and object of the mashing vessels used in the breweries, that, on the present occasion, our attention will be more particularly directed to the next and following processes."
"The Noted Breweries of Great Britain and Ireland, vol. 2" by Alfred Barnard, 1889, page 194.

That's what I've been waiting for: the capacity of the mash tuns. At 4 barrels a quarter, that's 80 barrels a brew per mashtun. Assuming one brew in each per day and 300 brew days a year, that comes to 48,000 barrels annually. Not enormous by English standards, but a reasonably-sized regional brewer in Scotland. Thanks for not bothering to describe them in any more detail, Alfred. At least there's an illustration.

Looking at the way that bloke is standing in the mash tun, it doesn’t look like it has internal rakes. Which tells me something. What? That they almost certainly didn’t perform underlet mashing like London brewers. About an hour into the mash more hot water is added to the mash from below (via the underlet, hence the name) to increase the temperature of the bed. It’s a simple form of step mashing. Whitbread were still mashing this way at Chiswell Street in the 1970’s.

Underlet mashing is one of the reasons many London brewers retained internal rakes even after installing a Steel’s masher. Because the practice was to have the rakes revolve once or twice after the underlet to mix the hot water added thoroughly with the grain.

"After this we made our way to the cooling department, covering the top storeys of the adjoining building, and overlooking the main thoroughfare. One of the most striking objects it contains is the hop-back, a large vessel with a graduated bottom, constructed entirely of copper, and containing across its breadth, at the far end, two rows of copper draining-plates. This vessel is used as a combined hop-back and open cooler, and is unlike any we have seen before.

In the same apartment there are two Morton's refrigerators, cooling at the rate of thirty barrels per hour each, where the ale wort is further cooled over the mazy lines of innumerable cold-water pipes before passing into the  great copper mains, which convey it to the fermenting rooms."
"The Noted Breweries of Great Britain and Ireland, vol. 2" by Alfred Barnard, 1889, page 194.

I wouldn't have minded an illustration of that cooler/hop back device. I can't quite get an image of it in my head. We all know what a Morton's refrigerator is, don't we? No? OK then. It's a bed of horizontal copper pipes through which chilled water flows. Wort flows over the pipes and is cooled.

"Our progress was now downwards, and after inspecting the furnace fires, or copper hearths, as they are called, we made our way back to the courtyard.

Passing beneath the archway, immediately within, on the left-hand side, appears the magnificent tun-room, re-built in the year 1866 and again considerably altered and enlarged in 1878. The building is of solid construction, and is lighted by nine windows in the roof, which contains improved patent ventilators, is ceiled with pitch-pine, and is supported by immense iron columns All the vessels are elevated on brick piers, and fronted by a gallery, which adds much to the impressive effect. The illustration, which heads this chapter, is taken from a photograph, and shows a section of the interior of this tun-room. There are fifteen vessels in this department, all constructed of polished pine, nine of them are fermenting squares, and the other six settling backs, and each is fitted with an attemperator. The copper mains, by which they are filled, are in short lengths and detachable, so as to be easily cleaned. At one corner of the room there is a small Otto gas engine, used for pumping the beer from the tuns into the backs. From this side of the brewery the beer is conveyed through great copper mains, laid under the street, to the racking-rooms on the north side of the brewery. Before leaving this place, we paid a visit to the engine-room, situated under the mashing-stage, and containing an engine of fifteen horse-power, and a large steam boiler. Here also are two sets of pumps for the coolers and refrigerators, reversible, in case of breakdown, and the two great metal underbacks, each fitted with duplicate stopcocks. Walking through this apartment we came to a paved chamber where the spent hops are pressed. The machine is worked by hydraulic pressure, and the wort expressed from the hops is pumped up again to the refrigerators, from which it passes to the fermenting vessels.
"The Noted Breweries of Great Britain and Ireland, vol. 2" by Alfred Barnard, 1889, pages 194-195.

It's clear that Aitken's brewery had been increasing its size and updating its equipment frequently in the second half of the 19th century. Boom days for Scottish brewing.

I'm not 100% sure what is meant by "nine of them are fermenting squares, and the other six settling backs". Fermenting squares I understand. You can see them in the illustration. Settling backs sound to me like part of a dropping system. It's a shame there's not more description of how these two types of vessel were used.

Fullers had fermenting rounds from which fermenting wort was dropped into settling squares. The way Fullers system of fermentation worked, the beer was only in the rounds 24 hours and several days in the squares. I can't see that working with the setup at Aitken, where there were fewer settling backs than fermenting squares. My guess would (and this is only a guess) that the beer was transferred to the settling backs when fermentation was pretty well complete. That would tally with the description of beer sometimes being put into squares in Edinburgh breweries, mostly to cool it down.

Those fermenting squares look pretty large to me. Look at the height of the things. I reckon they must be 12 feet square and the wort at least six feet deep. A quick calculation (an imperial gallon is 277.42 cubic inches) gives me a figure of about 150 barrels. That's much bigger than the piddling 40 or 50 barrel ones they had at William Younger. Which might explain why they need the settling backs. A larger volume of fermenting wort generates more heat.

Pressing spent hops to squeeze out the last drops of wort was becoming commonplace in large industrial breweries. I'm sure it still goes on today. But what about the quality of the wort extracted? Wouldn't it tend to be full of crap from the hops?

There will be at least more more instalment on the old Aitken brewery. Then we can move on to the recollections of former Aitken employees.

London vs Edinburgh system of brewing

Cleansing. The differences are all to do with the method of cleansing.

"In the fermenting rounds yeast is added to the wort, and the fermentation thus set up is allowed, in the Edinburgh system of brewing, to proceed for about four or five days, the temperature of the wort being kept within proper limits by the use of the attemperators or coils of pipes, through which cold water can be passed. During fermentation a portion of the saccharine matter in the wort is converted into alcohol, and carbonic acid is at the same time evolved. The reduction of the saccharine matter, or "attenuation," as it is called, is accompanied by a rise in the temperature of the wort, and it is this increase in temperature which has to be kept under control by the use of the cold-water pipes we have mentioned. When reduced to within two or three degrees of the required attenuation the contents of the rounds are run into the cleansing squares, where the beer deposits its yeast, becomes gradually cooled and fined, and in from twenty-four to thirty-six hours is fit to be drawn into casks, when hops are added to it, and it is stored or sent out to customers, as the case may be.

It is in the mode of conducting the fermentation, more perhaps than in any other portion of the brewing process, that the difference between the various so-called systems of brewing followed in this country exists. What is termed the Scotch, or, more properly, the Edinburgh system of brewing, which we have above described, is but the continuation or growth of a system of fermenting and cleansing began and practised on a small scale a long time ago. Formerly, the Edinburgh brewers used only the fermenting rounds, and cleansed from them direct into the casks sent out to their customers, the fermenting and cleansing or settling occupying from one to three weeks, according to the state of the weather and the quality of the ale. The ale so cleansed was quite "fine," and required no "topping up" in the casks. Now, however, the use of cleansing squares, such as those shown in our engravings last week, has become almost universal in Scotland, and, in fact, entirely so in the eastern parts; and the whole operation of fermenting and cleansing is completed in about a week. In the Edinburgh system the fermenting rounds are always kept of moderate dimensions or comparatively shallow; their capacity seldom exceeding forty barrels, or, if they are larger, they are made of such a diameter as to contain the required quantity of worts without the depth exceeding about 4 ft. This enables the temperature of the fermenting wort to be controlled with a moderate amount of refrigerating power.

The London system is in many respects the reverse of that practised in Scotland, the business of brewing being carried on in the metropolis on a gigantic scale, and the plant employed being large in proportion. Thus the fermenting rounds have been allowed to grow with the coppers, and quantities as large as from 600 to 800, or, in some cases, considerably over 1000 barrels are fermented in one tun, the depth being often from 12 ft. to 15 ft. With such large quantities the heat becomes uncontrollable, and subdivision into pontoons or their equivalents is a necessity. The "double square" system prevailing through the north and west of England is the same in principle as the old Edinburgh method. The double squares in which the fermentation is carried are, as it were, made by dividing an ordinary square at the middle of its depth, and making the upper part a yeast chamber, whilst the pumping of the beer from the lower to the upper square, and thus mixing it with the yeast to stimulate it, is somewhat analogous to the rousing of the yeast into the beer practised by the Edinburgh brewers for the same purpose. The Burton and some other English brewers follow the London subdividing system, but, instead of the pontoons or cleansing rounds, they employ the well-known "union casks." In the case of the Burton brewers it is the practice to stimulate the gyles with large proportions of yeast, and to thus bring about very much the same result as is obtained in London breweries by the large bulk contained in the fermenting rounds. There are, however, some other peculiarities connected with the Burton system, of which, together with special points in other systems, we shall speak in due course."
"Engineering, Volume 5 - from January to June 1868", 1868, page 464.

Wasn't that fascinating? Let's pick through the bones and see what meaty tidbits we can find to chew.

Originally in the Scotch, or Edinburgh system, fermentation and cleansing both took place in small rounds. No intermediate vessels were used between the rounds and the trade casks. However, by the time the article was written (1868) most Scottish brewers had introduced settling squares for cleansing. This sounds very much like the dropping system. Fermentation begins in a tall round fermenter and later the wort is dropped into a shallow settling square below (hence the dropping bit of the name) were fermentation is completed and the yeast settles out.

Except there's one big difference. In the dropping system as practised at Fullers and some other Southern breweries, the wort remained for only a short period in the round. Typical was 24 hours in the round and 5 or 6 days in the settling square before racking. In the Scotch system described above, the wort stayed in the rounds until fermentation was almost completed.

I'm sure that some of the differences were, as the author explains, due to the difference in scale between brewing in London and Scotland. As we've seen, the largest London brewers produced as much as all of Scotland. Their breweries had been designed to churn out enormous quantities of Porter and everything was on a grand scale. Even a comparatively small brewer like Fullers had fermenting vessels capable of holding more than 200 barrels.

Preventing the temperature of the wort seems a recurring theme. Hence the shallow Edinburgh rounds. Being shallow is probably also the reason why they'd been able to get away without using settling squares initially. Yeast will settle more rapidly in such a vessel. You could see this type of fermenter as a round and settling square combined. Looking at William Younger's brewing records from 1868, I can see confirmation of the small fermenter size. The largest wort I can find was 55 barrels. Most were 40-odd barrels.

I've just been taking a closer look at those Younger's records. And I think this text has helped me understand them better. Their worts spent 3 to 5 days in the fermenting tun and then 1 to 3 cleansing in a square before racking. The fermentation was in most cases, as the text says, within a few degrees of their final attenuation. Mostly just a couple of degrees (in SG). For example, 1036º to 1035º; 1030º to 1025º; 1017º to 1013º; 1017º to 1016º.

Part of a William Younger's brewing record from 1868 (document WY/6/1/2/21 at the SBA)

I think we all know what the "double square method" is: a Yorkshire square. Intriguing that this is likened to the Edinburgh system. Because, sure enough, there in Younger's records are the "beats" - beating the wort to rouse it. It had never occurred to me that this was the same concept as the continual rousing of a Yorkshire square. Which leads on to another question: what impact did this have on Scottish yeasts? Those used in Yorkshire squares had adapted itself to the constant rousing and wouldn't work well in a standard fermenter. Were Scottish yeasts the same?

Pontos at Watney's Stag Brewery in London

Pontos (called pontoons here) I think we all know about. They are a forerunner of union sets, basically large casks from which the yeast is allowed to escape through the top. The difference with unions being that the casks were upright rather than on their sides and needed to be topped up manually. The troughs and pipes of a union set effectively automated the topping up process. William Younger had unions of their own. Though these, in imitation of Burton, were only used for their Pale Ales.

Amazing, isn't it, how much you can learn from three paragraphs of text.

The three systems of fermentation 1880-1914

More laugh a minute stuff from "Principles & Practice of Brewing" by Walter J. Sykes & Arthur R. Ling, published in 1907. I wonder if I still have any readers left?

It's not surprising that the more labour-intensive methods described below have disappeared. Even the most sophisticated method of cleansing, Burton unions, is pretty fiddly.




The cleansing system
Probably having its origins in domestic brewing, this was the oldest method of fermentation. Originally, trade casks, that is the casks in which the beer was sent out to customers, were used for cleansing. After about 48 hours in the fermenting tun, the process of separating out the yeast began and the wort was transferred to trade casks. A few breweries still used this old-fashioned method in the early 20th century.

By the late 1800's, it was more usual to use large casks - butts, puncheons or pontos, each holding several barrels - for cleansing. These were known as "loose pieces" because, unlike the more sophisticated Burton Union method of cleansing, the barrels were not permanently fixed to a frame, but could be removed for cleaning. Yeast was pitched at 56º to 60º F and after 36 to 40 hours, when the temperature had risen to about 70º F and the gravity reduced by half, the wort was transferred to the cleansing casks. Splitting the wort into smaller volumes helped to keep down the temperature. If the temperature in the fermenting room was 45º to 50º F, the wort in the casks could get no warmer than 70º F.

In the summer, it was possible that the wort could become too hot so, as a precaution, it was moved to the cleansing casks earlier in the fermentaion, when it was cooler. Burton Unions were fitted with attemperators, so this was not necessary.

Some beer was expelled along with the yeast and it was important to top up the cleansing casks with clear wort. If they were not keep totally full, yeast would fall back into the beer and defeat the object of the operation. In some arrangements, such as Burton unions, topping up occurred automatically. In other cases, it was performed by hand, usually at intervals of around 3 hours.

As far as I am aware, the unions at Marston in Burton are the only remaining example of this form of fermentation.


The skimming system
This began exactly the same as the cleansing method. When the skimming point was reached, the wort was left in the fermenting tun but thoroughly roused. The yeast head was skimmed off every 6 hours. Temperature was controlled by means of attemperators. These were switched on when the temperature of the wort had reached 59º F and so regulated as to allow the wort to rise 1º F every 6 hours. The flow of water through the attemperators was increased when the wort hit 65º or 66º F to stop the wort warming any more. When the fermentation was nearly finished, the the water flow in the attemperators was increased even more to cool the wort down to 60º F.

Skimming stopped when it was estimated there was just enough yeast left to throw up one more head. This was checked by moving aside the head to look at the wort. If it was black and clear, it was ready and no more skimming was needed. If it was brown and opaque, it still contained too much yeast.


The dropping system
This was a variation on the skimming system developed by William Garton. When the wort had almost reached the skimming point, it was let down from the fermenting tun to a shallow settling square. The process of "dropping" both aerated and roused the wort. Much of the sediment was left behind in the fermenting tun.

Once in the settling square, the wort was skimmed and its temperature controlled by attemperators as in the skimming system.

Fullers were using the dropping system in 1910. They usually dropped the wort after just 12 to 18 hours in the fermenting tun. This is the record of a typical fermentation:


The temperatures match pretty much exactly those given by Sykes and Ling in their description of the skimming system.

Most London breweries employed either the cleansing system or skimming system. I am unaware of any brewery that still uses the cleansing system. There is at least one brewery (Refresh for the Brakspears beers) that continues to use the dropping system.


The stone square system
This method, as its alternate name "Yorkshire square" implies, was common in the north of England. It produced beers that were full-bodied and with a high CO2 content. A special type of slow-acting yeast, which needed a great deal of rousing, was used.

A small amount of yeast, just 1 to 1.5 pounds per barrel, was pitched at a temperature of 58º to 59º F. The yeast was mixed with a little wort in the upper chamber, thoroughly roused and then let down into the main chamber through the "organ pipe". The wort was then left undisturbed for 36 hours during which time the temperature rose to 62º F. For the next 12 hours, the wort was roused every two hours. Yeast rose through the central manhole and settled in the upper chamber.

The next stage was pumping. Wort was pumped into the upper chamber and mixed with the yeast that had settled there. The valve in the organ pipe was then opened to allow the wort and yeast mixture to run back into the main chamber. This process was repeated every two hours, starting with 15 strokes of the pump. On each subsequent repetition, the number of strokes was increased by 10. The wort was kept cool by the attemperating "jacket" formed bt the double walls of the square. Pumping ceased when the wort was within 1 or 1.5º of its finishing gravity.

After pumping was over, the yeast which rose into the upper chamber was removed any four hours. Any beer which had risen with the yeast was let back down into the main chamber through the "organ pipe". When all the yeast had been removed, the temperature of the beer was gradually reduced to 60º F. The manhole was then closed and the beer left to settle for 48 hours before being racked.

Yorkshire squares are the only one of the three fermentation systems still in widespread use. Breweries using them include Sam Smith's and Tetley's.

Fuller's fermentations 1910

I just can't leave this topic alone. Sorry about that. At least one of you finds it interesting, too. Reason enough for me to continue.

These are the other three beers I've found in the 1910 Fuller's brewing records, P (Porter), BS (Brown Stout) and PA (Pale Ale).

Just to recap, AK was dropped after 66 hours and fermentation took 159 hours, X was dropped after 12 hours and fermentation took 129 hours.


You can see a similar pattern. The PA had a longer, slower fermentation than the Porter and Brown Stout, 158 hours against 134 hours. It was also in the round much longer, 41.5 hours as opposed to 12. There was far less difference in the length of time spent in the settling squares: 122 hours for P and BS, 116.5 for PA.

There's not a huge difference in the attenuation of the different beers:

BS 71%
X 72%
P 75%
PA 78%
AK 80%

Though the AK and PA are the most attenuated.

The amounts of yeast used were:

BS 93 lbs for 98 barrels
X 136 lbs (Mann's yeast) for 183 barrels
P 87.5lbs (X brew 71 4th crop yeast) for 200 barrels
PA 318 lbs for 212 barrels
AK 122 lbs for 188.5 barrels

I'm not exactly sure what this tells us. Except that the fermentation of the Bitters - PA and AK - was quite different to the other beers.

The dropping system of fermentation

I'm such a populist. I should try choosing more obscure topics. Or you'll start calling me the Daily Star of beer blogs.

I was much intrigued by the dropping round and settling square kept as a museum piece in the Fuller's brewery. For one thing, it gave me chance to see exactly what an attemperator looked like. And the brewer, John Keeling, explained to me how it worked. He told me that the wort was usually dropped after 12 hours or so. The exact timing being determined by the type of head that had formed.

The Fuller's logs are full of information. Including complete fermentation details. And they tell you when the beer was dropped. Looking at their bog-standard X Ale, that's exactly what happened. It spent just 12 hours in the round. As did the Porter and Brown Stout. The PA stayed in the round longer, 41 hours. But the AK I have the log for was in the round 66 hours.


The fermentations for the PA and AK are quite different from those of the other beers. The majority took place in the round. About two thirds of the gravity drop was in the round. For the darker beers the fermentation had barely started when the wort was dropped into the square.

Could it be that time in the round was connected to the degreee of attenuation? The AK is the most fully-attenuated.

You'll notice that the fermentation of AK took considerably longer, despite it having a lower OG. Thirty hours longer, to be precise. Before you ask, both the X and AK were brewed at the same time of year. The AK was brewed on the 14th March 1910, the X 10th March 1910.