Sparklers, little attachments to a beer engine’s nozzle that aerate the beer and produce a bigger head, are a bit of a controversy. Northerners stereotypically swear by them, Southerners despise them, etc. Personally, I think they make sense with some beers, but not so much with others. My personal hypothesis is that a lot of cask beers are brewed with the intention of being dispensed with or without a sparkler. A pint of Landlord without a thick head on top would certainly be weird, while London Pride served through a sparkler was probably one of the grossest pints I’ve ever had.
Most people think that this is probably a problem only cask beer aficionados in England face, but at least in the 19th century, lager beers in Germany and Austria directly dispensed from wooden casks were served in a similar way: besides the regular tap, a device called Mousseux-Pipe, sometimes also called Bierbrause (lit. “beer shower”), was also quite common. I’ve never seen an actual photo or illustration of one, but the descriptions of it make it sound very much like a sparkler: when beer was dispensed from a cask through the Mousseux-Pipe, it foamed up and produced a bigger, denser head.
As with every aspect of beer, the effect of this dispensing method also came under scrutiny by beer researchers. Th. Lange compared how much carbon dioxide was lost when dispensing from a regular (wooden) tap compared to dispensing from a Mousseux-Pipe, both with bunged and unbunged beer.
The total loss of CO2 when pouring bunged beer was 14.6% from a regular tap, and 22.72% from the sparkler tap. For unbunged beer, which is lower in CO2 in the first place, the loss was slightly lower: 10.27% from a regular tap, and 14.03% from a sparkler tap. (Source)
What’s also interesting is the amount of CO2 lager beers were served in the late 19th century: a regularly carbonated (bunged) beer contained 3.9 g/L (= 1.99 volumes) of CO2, a medium-bunged beer 3.457 g/L (= 1.76 volumes), while an unbunged beer contained as little as 3.097 g/L (= 1.58 volumes) of carbon dioxide. Compared to the typical carbonation of modern beer, this is fairly low: modern lager beers are often carbonated at around 5 g/L or roughly 2.5 volumes, while cask ales are carbonated lower at roughly 2.9 to 4 g/L (1.5 to 2 volumes).
So when we’re looking at the historic carbonation rates, it clearly shows that they are more in the range of what we get in modern cask ale. These historic lager beers seemed to have been more gently carbonated, making for a nicer drinking experience, something that you would find also in beers gravity-poured from wooden casks in Franconia.
Just like its modern counterpart in England, the use of Mousseux-Pipen was not uncontroversial either: in Tyrol, the use of syringes of similar devices to create artificial foam in beer was prohibited from 1854 on for sanitary reasons. A letter to the editor in a newspaper from 1871 laments the “strict non-enforcement of this edict got rid of syringes” and popularized beer showers that produced a thick and dense foam that helped defraud customers through underpouring.
Some publicans also saw sparkler taps as an issue: the wooden casks of the era were not entirely tight, so they gradually lost carbonation. Combined with a sparkler tap and the agitation when transporting, handling and tapping the casks, this led to an unacceptable amount of carbonation loss resulting in flat beer.
The organization of Viennese brewery owners even blamed assertions of beer adulterations on poor beer pouring practices: beers that tasted overly bitter were accused of using something other than hops for bitterness. Practically, beer that was poured hard and through devices like sparkler taps ended up flat, and no CO2 to soften down the hop bitterness. The Viennese brewers therefore suggested to pour beer as little as possible, and with as little devices in between. Instead of getting beer poured through a sparkler tap into a jug or large bottle, and then carried all the way home, beer should ideally be poured directly into a glass through a regular tap, and protected from sun and heat while bringing it home.
All in all, Mousseux-Pipen seemed as controversial back in the day as sparklers are in England nowadays. While I couldn’t find anything definite, I’d say the practice at the very latest died out when gravity-pouring beer from cask fell out of fashion, and more modern top-pressure-based dispensing methods became popular. And frankly, in the narrow context of gravity-poured lager beers, I don’t really see the need for it, as I’ve never seen such a beer freshly poured from a cask suffering from any foam issues, while still having a gentle carbonation that makes it easy to drink. Maybe brewers have become more knowledgeable about brewing beer with greater foam stability, or the slightly higher carbonation of modern lager beer is making a difference, or maybe the higher quality of modern “wooden” casks (most of which are metal-lined nowadays) means less CO2 leakage and a better retention in carbonation. In any case, a properly poured beer directly from a cask, with a nice thick head on top, makes for a great presentation, and I crave one now.