Tales of the Worm Tub

Join Lee "Connas" Connor as he unravels the magic behind the ancient worm tub condenser and its role in modern-day whisky production

Photos by Mike Wilkinson and Peter Sandground

MORE THAN MEETS THE EYE

Transporting you back in time the Society’s latest Creators Collection, Tales of the worm tub, lets you experience a different era of Scotch whisky distillation. Since shell and tube condensers came to dominate Scotland’s distilleries in the late 1960s, worm tub condensers have become somewhat of an anomaly in today’s whisky landscape. However, not everyone has been won over by the more efficient lure of the shell and tube condenser – a select few choose to embrace the untamed nature of this old-school distillation technique.

Fermentation, distillation and maturation. Making whisky is easy – if you forget about the barley, malting regimes, milling, mashing, yeast selection, fermentation times, and spirit cuts. Similarly, condensing is part of a long list of processes that is often overlooked when we discuss spirit character. Though the facts of the matter suggest that we’ve known about the benefits of effective condensing for a long time. Back in 1705, distiller and alchemist William Y-Worth once said that correct equipment and process can take “away part of the groſs sulphur, from whence (much of) the evil tang proceedeth.” We now know that different methods of condensing spirit can impact both the flavour and texture of the spirit being made. From the illicit origins of Scotch in the 1500s to the present day, arguably the most recognisable is the ‘worm tub’ condenser.

TRIED AND TESTED

Look at any image depicting a historic scene of illegal distilling in Scotland and you’ll see one. Experiences and visitor centres are strewn with examples of them. A small copper pot still with a length of coiled copper piping attached to the line arm descending through a tub filled with water to a spout protruding at the bottom. The humble worm tub has faced and survived all of the trials and tribulations that the whisky industry has been beset with, from taxation and industrialisation to efficiency modularization. Even the invention of the more reliable, easier to maintain and more versatile shell and tube condenser has not undone its simpler older predecessor. But why would distilleries knowingly go out of their way to choose the less efficient condenser? The answer is character. Worm tubs are renowned for producing a very distinct oily and heavy spirit, the like of which has remained elusive to newer solutions

Despite being less efficient, worm tubs are still used in modern Scotch whisky production

BUILDING A BASE

In dissecting the role that worm tubs play in making whisky, we must first look at where in the process they perform their task. We can put maturation aside and concentrate on what the worm receives – vapour. This vapour has been formed from a liquid at the end of its second distillation, after being fermented from a mash of malted barley called wash. When creating their wash, distilleries will experiment with shorter and longer fermentation times to create different characters.

The job of distillation is to encourage the development of these flavours into the final distillate, while also increasing the alcohol. To do so, the distiller must analyse their wash and set their chosen still to boil at a certain temperature to collect the desired vapour concentrations at the top of the still. In doing so they must also consider the impact of the copper the stills are made from. This copper contact strips some of the heavier compounds within the liquid and vapours from the eventual gaseous material that travels over the line arm and into the condenser.

IN THE TUB

We now have our vapour trapped within a long spiralling copper pipe, sometimes up to 100 meters long. The pipe declines into a vat of cool water where the vapours will be transformed back into liquid. For this part of the process, it can be helpful to think of condensing as ‘distilling in reverse’. In other words, the amount of copper contact and rate of cooling (as opposed to heating) will determine some of the eventual spirit character.

As the vapour travels along the worm, it coats the entire inside of the pipe, giving the maximum opportunity for striping away heavy compounds such as sulphur. The sooner it is cooled back into liquid, the less copper contact their will be. In theory, this means the quicker the vapours recondense the more robust the final spirit will be. The speed of recondensing largely depends on the temperature of the cooling water. Warmer cooling water means more copper contact, and vice versa. As most worm tubs are housed outside of distilleries, this can result in seasonal changes in production protocols.

Also, maintenance of the worm will play a part in the story. Build-up of a heavy sludge where liquid meets the pipe can carry over in the spirit, so character must be monitored to determine cleaning regimes. Although being the more traditional method of condensing, it’s clear that worm tubs need a relatively high level of maintenance and are less likely to produce the light spirit that has become preferable in today’s market. It’s younger more versatile sibling, the shell and tube condenser, is much more suited to this style and to many is seen as the more sensible option. And yet worm tubs are still a key pillar in the Scotch whisky industry, and the few distilleries opting for their use rely heavily on their distinctive style.

Worm tubs at Craigellachie distillery

Three whiskey bottles with glasses on a table in a cozy setting.

Our latest Creators Collection, Tales of the Worm Tub

HEAVY-WEIGHT DIVISION

Through different climates, still temperatures and worm lengths, it’s clear that worm tubs can produce a diverse range of spirit characters. To properly understand why a select few distilleries across Scotland still choose these condensers its worth tasting the range of flavours they offer first hand. The Society’s latest Creators Collection, Tales of the worm tub, is the ultimate flight in worm tub distillation and will give you an insight into this ancient technique you won’t find anywhere else. Cask No. 36.228: The snaking coil, Cask No. 76.157: Behold the beast and Cask No. 44.190: Unleash the serpent will transport you back in time to a different era of Scotch whisky distillation. Each offering a unique take on this condenser’s style, there’s no better way to discover the thick unctuous flavours worm tubs have to offer.

What worm tubs produce is a specific texture and mouth feel. A weighty mid palate and oily textures that cling to the mouth. In terms of cost, maintenance and even consistency worm tubs arguably don’t make much sense anymore. But their continued use is testament to their distinctive style of bold, muscular, nutty, oily and rich whisky that has played an integral part in diversifying the palate of modern-day scotch whisky. Sometimes there’s more to flavour than efficiency, and the raw untamed nature of this old-school distillation technique is the perfect example.