While it might seem like a minor, mundane detail, I keep getting asked what an “English kiln” was, particularly in the context of 19th century Continental beer brewing. English kilns are mentioned in the context of Anton Dreher (who personally witnessed British malting techniques), and the Burghers’ Brewery in Pilsen, nowadays better known as Pilsner Urquell, is also often mentioned as having used one since 1842 (just Google “english kiln” “pilsner urquell” and you will find plenty of sources). But what is usually not answered is: what actually was an English kiln? Any kiln designed or built in England, or rather a specific type, and where does the association with England come from anyway?
So when I started searching for sources, I was very surprised to find an 1785 book about fuel efficient stoves with a description of what is called an English malt kiln (“englische Malzdarre”), including technical drawings. Essentially, this English kiln used hot air to kiln the malt, and it generated this hot air by directing its hot smoke through a maze of pipes that would transmit the heat to the air, without the smoke ever touching the malt itself.
The next reference to a hot air kiln that I could find was Hermbstädt in 1826. He was a respected early brewing scientist in Berlin at the time, but admitted that he had never seen nor built a kiln that just uses hot air. The thought of it seemed important enough to him that he floated the idea in his book, which was basically an oven that would heat up a metal pipe to be glowing hot which would in turn heat up the surrounding air. This hot air would then flow through the green malt and carry its humidity with it and out the chimney.
But already in 1831, Leuchs mentioned two principal types of kilns: smoke kilns and hot air kilns, followed by a one sentence comment: “in England the latter types of malt kilns are often placed underneath the drying floors.” This is the first source I could find that directly associates hot air kilns with England, not just in name, but specifically as a place where these were being used.
Professor Balling, the legendary Bohemian brewing scientist, makes a similar point: hot air kilns were first built and used in England, and are thus also called English malt kilns.
All these authors recognized the advantages of hot air kilns, though: not only was the hot air dry and thus very effective in drying out the malt, it also prevented the smoke from touching any of the grains, thus not transmitting any smoke flavour into the malt. With smoke kilns, maltsters had to be careful which fuel to use, and generally, only properly dried and cured hardwood like beech or oak were used that would impart only a slight smokiness that was not unpleasant. With hot air kilns, it was possible to switch to other, cheaper fuels that could burn dirtier than old-fashioned smoke kilns, making malt production cheaper.
Interestingly, an 1846 brewing book by Julius Gumbinner discusses two different constructions of English malt kilns, but then also goes on to describe Bavarian kilns which apparently were still fairly widespread in Bavaria at the time, and were essentially what was called Dutch kilns, an advanced type of smoke kiln that tried to minimize the contact of smoke with the malt so that it imparts as little smoke flavour as possible.
In 1850, J. F. Schultze mentions hot air kilns and calls them English malt kilns, but also briefly describes a different type of malt kiln, the Brabant malt kiln but apparently (besides kilning malt) could also be used to pre-dry malt (something that German maltsters at the time would do at room temperatures over several days) as well as drying freshly harvested grains in general. The specific distinction in construction is not entirely clear to me, but Schultze claims both types had some disadvantages which could be alleviated by combining the English and Brabant malt kiln design.
Philipp Heiß, former brewmaster at Spaten, published a brewing book in 1853, and of course briefly mentioned kilns. He referenced Balling, but adds another detail for nuance: at the time, some English maltings still used very simple coke-fired smoke kilns. Heiß also corroborates Schultzes mention of Brabant hot air kilns, but he mentions the Netherlands as a place where maltings employed hot air kilns that used simple clay pipes to transmit heat from the smoke to the surrounding air (i.e. they have no connection to the Dutch kilns mentioned by Gumbinner).
Ladislaus von Wágner goes even further in his 1877 book where he claims that the term “English malt kiln” is inaccurate because England is the place were hot air kilns are used less often compared to Austria-Hungary and Bavaria where breweries had mostly switched from smoke to hot air kilns.
After reviewing all this literature, my impression of what an English kiln was during the 19th century has certainly improved: an English kiln was simply a hot air kiln that allowed smoke-free kilning of malt, and it was named an English kiln because the technique of hot air kilning seems to have first been applied in England, even though coke-fired smoke kilns remained in use there for a relatively long time.
There seemed to have been lots of different constructions of how these kilns were built, and German engineers surely quickly adapted and came up with lots of different designs. I even found one book from 1881 with a whole chapter on all the possible details how to construct kilns. But the idea of smoke-free hot air kilns seems to have been around for a long time, and at least somewhat documented in brewing literature of the first half of the 19th century. All it needed was young, curious brewers and maltster to pick up these books, learn about English kilns, and adopt them in their own breweries. None of that seemed secret or even involved industrial espionage (like some contemporary beer books suggest), nor did it require the import of kilns built in England.
Probably the most useless fact that I picked up during this research though was from a book that advertises different kiln constructions: what do the breweries Tetley & Sons (Leeds), Schultheiss and Landré (both Berlin) have in common? They all had the same specific model of hot air kiln installed, by E. Münnich & Co in Chemnitz. Remember that for beer history trivia night!