A Traditional Product from Modern Production

The production process of single malt whisky has remained almost unchanged for centuries now. If you want to know about the basics of single malt whisky production, please read our article here.

This article deals with the modernisation of the single malt whisky production process over the past centuries.

A monitor with 6 stills on them. 3 spirit stills and 3 wash stills.
A monitor for the stills at Mortlach

At the beginning of the industrial production of single malt whisky, the first goal was to guarantee the continuous quality of the whisky. The next step was to increase the efficiency of whisky production. As with all technical processes, the engineers put special attention to the balanced relationship between attainable efficiency (raw material use, energy consumption) and the costs for the improvements. The costs of whisky production can roughly be calculated as follows:


CW ~ CB / EM + CE / EE + CL + CS + CC


CW - Total costs of whisky production

CB - Barley purchase price by distillery

EM - Mash efficiency factor

CE - Energy costs by distillery

EE - Efficiency of the energy conversion

CL - Labour costs

CS - Costs of whisky storage

CC - Capital costs for investments (machines, buildings,... )


In the past especially barley and coal were the focus of the optimisation efforts, since these materials produced the highest costs. In the course of these efforts, the complex mash procedure usually used today was developed, which extracts the sugar from the barley optimally. The process of turning starch into sugar could also be optimised in industrial maltings.

A shiny stainless steel mashtun
Closed mashtun at the Strathmill distillery

In the past especially barley and coal were the focus of the optimisation efforts, since these materials produced the highest costs. In the course of these efforts, the complex mash procedure usually used today was developed, which extracts the sugar from the barley optimally. The process of turning starch into sugar could also be optimised in industrial maltings.

The energy consumption was also reduced significantly in the past centuries. Closed mash tuns were the start. They were followed by improved heating systems using hot steam instead of direct coal firing. Energy recovery is also an inherent part of the whisky production today. Simple coolers were replaced by heat exchangers, which extract the warmth of a liquid and reintroduce it to the production process. The hot pipes and containers are insulated to preserve the expensive energy.

An open mashtun in the front and an closed in the back
A Glenfiddich mashtun without the lid

Today the use of barley and energy is optimised to a large extent, no longer allowing for a competition advantage over other distilleries. After all the optimisation potential had been tapped, new ways such as working in three shifts had to be found to amortise the investments in the machines and buildings as quickly as possible. Today all large distilleries work 24/7 on all days of the year. The distilleries are only closed for 3 to 6 weeks a year for a maintenance and repair break.

The empty mash tun with a turning rake inside
The Glenfarclas mashtun after the cleaning process

Today mainly the use of labour and capital can still be optimised. In June 1998, United Distillers (today Diageo) announced plans to cut hundreds of jobs, the reason being the merger of Guinness and Grand Met, which made many jobs in the administration and distribution redundant. But in many distilleries a lot of jobs were also cut in production due to automation.

Some tube at the top and a collecting can at the bottom. Inside the pot still. There are 4.
The cleaning system inside the Glenlossie pot still

Many distilleries reduced the nightshift to one person through automation. This single person is responsible for the mashing as well as for the two distillation processes. Mashing and distilling limit the capacity of a distillery. Mash tuns and pot stills are the bottleneck machines in the production process. So these bottleneck machines are run in three shifts, thereby distributing the fixed costs of the capital assets (machines, buildings) on as many litres of whisky as possible.

Fermenting, mashing and distilling are batch processes, i.e. a certain amount of raw material is always processed at one time. Unfortunately, wash backs, mash tuns and pot stills get so dirty they must be cleaned after each batch. This cleaning is labour-intensive, since burnt-in substances must be removed from the container walls with steam. For years chemical cleaning agents have been used. Time and again distillery workers had to get inside the containers to clean difficultly accessible areas.

Since the summer break 1997, the wash backs and pot stills of the first distilleries have been equipped with automatic, central cleaning systems. The spray nozzles are connected with central storage tanks for the cleaning solution. After each batch the containers are cleaned for five minutes to get rid of the sticky remnants of the batch.

Beside saving labour costs and sparing the operating personnel, this central cleaning has another advantage. After the cleaning solution has been applied, the containers are rinsed with clear water for 20 minutes to make sure all the remnants of the cleaning liquid are removed. The central supply and drainage of the cleaning liquid ensures that the liquid is completely recycled. Here you can see again that an economically sensible use of resources can also be good for the environment. Meanwhile almost all operators of pot stills have switched to this automatic cleaning process.

Wash backs used to be made of Oregon pine. This type of wood was most resistant to the attacks of the yeast fungi. Unfortunately these wash backs had to be protected from fungi and bacteria with extreme cleaning agents. The introduction of stainless steel tanks, which had long been used in the beer and grain whisky production, also relieved the environment from a majority of the cleaning agents.

A steel washback of the Longmorn distillery
A modern stainless steel washback of the Longmorn distillery

Some argue that whisky from wooden wash backs tasted better than whisky from steel wash backs, but I think that's nonsense, since the liquid only stays in the wash backs for 40 to 70 hours, which is too short for any substances to be transferred from the wood into the liquid. Furthermore, the ratio of wash back surface to volume is 25 times smaller than the ratio of the cask surface to volume during the storage of the whisky. Multiply this ratio by the shorter time (50 h : 12 years = 100'000 h), and the influence of the wooden wash backs is 50,000 times smaller than that of the cask. If we are honest to ourselves, the ancient wooden wash backs just please our eyes more than their modern descendants.

3 wooden washbacks in a row at the Auchentoshan distillery
The Auchentoshan washbacks made of wood

But is the old way really better in this case, just because our ancestors couldn’t do it better? - I don't think so.

But everybody has to answer this question for themselves- or not. Who knows which whisky is manufactured in which way?

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