How to make Scotch whisky
The earliest record of distilling whisky in Scotland dates back to 1494, when Friar John Cor was instructed to buy “8 bolls of molt for the production of aquaviate”. The process of making Scotch whisky has changed since then, and even in the last hundred years, there have been significant advances in technology and production methods.
So, if you've ever wondered how barley, water, and yeast turn into the Scotch you enjoy, you're in the right place. Read on for a step-by-step guide of how we make whisky at Lagg.
Style and process
While the stages of making single malt Scotch whisky are broadly the same for most distillers, we can only tell you how we do things at our own distillery. This is because there are so many factors that influence the colour, flavour, characteristics and aroma of the final whisky - from the type of barley and yeast used to the size and shape of the pot stills.
Our new (ish) Lagg distillery, at the south end of the Isle of Arran, heralds the return of whisky production to the area in over 180 years. For our whisky to bear any resemblance to the Arran waters of yester-year - and that is indeed our aim - it needs to be smoky, meaty and full-bodied.
So, we’ve designed and built Lagg Distillery with this in mind.
Our spirit style is essentially light and fruity with oily mouthfeel. Yes, we run peated malt occasionally at 20ppm (phenol parts per million) and 50ppm ratings but we have never wanted (nor, truly been able) to produce the tarry, medicinal spirit style which many people would presume goes hand in hand with high peating levels.
And while we’re on the subject, let’s debunk a myth: “the higher the PPM, the smokier the taste”. In fact, there are multiple factors that sculpt a whisky’s flavour and influence your perception, including:
- How smoky the dram might taste.
- To what level was the barley pleated?
- Was the mash raked?
- How long was the fermentation?
- What’s the washback made from?
- Which yeast strain? What size are the stills?
- How fast are they run?
- What were the distillation cut points?
- What type of cask was the spirit matured in?
- How old was the whisky when it was bottled?
As you’ll discover below, the production method of a distillery has an enormous influence on the final whisky. This is our process at Lagg Distillery.
Malting
The journey of each Lagg Single Malt Scotch whisky begins with malting. We use 100% Scottish barley - around 94% comes from the east coast of mainland Scotland, and for a few weeks a year we create new make spirit with barley grown right here on the island. Once the barley is harvested, it’s then ‘steeped’, which allows germination to start. The malted barley is dried in a kiln of burning peat to stop the germination process and create a rich, smoky flavour in the malt.
The peat we use comes from the Highlands. You may think that we use Arran peat, but the simple fact is that there isn’t enough of it on the island. However, we are investing in a peatland restoration project which could change that for future generations, while also helping with our goal to become net-zero by 2040.
Mashing
The malted barley is then ground into a coarse mixture of flour, grits and husks called grist (read our guide on milling for a more detailed dive into this subject). The grist is mixed with hot water in our mash tun (imagine a giant teapot) to extract the sugars, creating a sugary liquid known as ‘wort’. At Lagg, our semi-lauter mash tun uses 4 tonnes of grist per mash, and is around double the size of our sister distillery at Lochranza (the home of Arran Whisky).
Another difference between the two distilleries is that here we rake the mash. Raking the mash refers to the process of agitating or stirring the mash in the mash tun, and we do this with a mechanical rake. Raking helps to even out the temperature throughout the mash, improve water flow and prevent clumping.
Lochranza’s clear, bright wort from almost entirely un-raked mash ensures ‘optimum’ yeast performance at fermentation and passes no solids to the washbacks. Conversely, our raked mash passes cloudy wort to fermentation, which is thick with additional non-fermentable compounds that slow the yeast’s progress and curtail an element of the fruitiness in the wash. This eventually translates to the spirit with more spotlight on nutty, earthy characters. Sure, fermentation may technically be less efficient, but we are more than willing to sacrifice a little yield in pursuit of our desired character.
Fermentation
Our fermentation process is long. Our M strain distillers yeast ideally suits the production of wash from peated malt, and it takes about 55-60 hours to ferment.
The wort is cooled and transferred to containers called washbacks, where yeast is added. We have four washbacks - all made of Douglas Fir - each with a capacity of 24,000 litres. However, during production they will each be filled with only 20,000 litres of wort for fermentation.
The yeast ferments the sugars in the wort, producing alcohol and a range of flavourful compounds. After a couple of days, the wash has an alcohol content of about 8% - equivalent to a very strong beer. As already mentioned, we have a very cloudy wash as we encourage all the fatty acids and esters to release from the barley, which will give the spirit a heavier, grassier, and earthier flavour.
The fermented wash now stands for a further period in yet another pine receiver before being distilled. This extra period allows further development in flavour, over and above washback fermentation.
Distillation
The wash is now distilled twice (the traditional way to do it in Scotland) in our custom-made copper pot stills, a process that separates the alcohol from the water and other impurities. Think of the stills as giant kettles with a heating element in the bottom that we put hot steam through.
Our copper pot stills were designed with a heavier, earthier spirit in mind, perfect for a heavily peated malt. We have two stills: the first still is the Wash, in the shape of a bulbous onion, with a capacity of 10,000 litres; and the second still is the Spirit, in the shape of a lamp glass, with a capacity of 7,000 litres.
The first distillation in the wash still produces a liquid called the low wines, with an alcohol content of roughly 25%. The low wines are collected for around 6 hours and then sent to a tank to be distilled for a second time in the spirit still. Its design helps to generate some of the flavour profiles of the whisky; ours are short and fat with a downward sloping lyne arm (connects the still head to the product condenser) to emphasise the heavily peated whisky we make.
As the low wines are heated in the spirit still, the alcohol and other volatile compounds vaporise. These vapours rise, condense, and are then directed through a spirit safe, where we can monitor the flow and make crucial cuts - a process where we separate the distillate so we can control the flavour and aroma. There are three cuts: heads, heart and tails.
The head (foreshots)
The head, also known as the foreshots, are the first vapours to emerge from the still, as they have the lowest boiling points. These highly volatile compounds, such as methanol and acetaldehyde, are undesirable because of their pungent and unpleasant chemical nose. We divert and re-distil the foreshots with the next batch of low wines, so we don’t waste any valuable alcohol and prevent those undesirable elements from reaching the main spirit.
The heart (middle-cut)
This is the prize of the distillation process. It is a pure, clean spirit known as new make spirit (with an alcohol content of 63.5%), that contains the perfect balance of alcohol strength and flavour compounds. It’s rich in fruity esters, malty sweetness, and the subtle notes that will be developed and deepened during cask maturation.
Getting this cut exactly right is crucial. Cut too early, and you risk letting in some of those harsh, volatile notes from the foreshots. Cut too late, and heavier, oilier compounds from the feints may muddy the flavour. When to make the cut will vary from distiller to distiller, and depends on whether you want a lighter, floral spirit, or a heavier, more robust distillate.
The tail (feints)
As the distillation continues, the alcohol content in the vapor drops significantly. The end of the run, known as the tails or feints, contains lower alcohol and a higher concentration of heavier, high-boiling compounds like fussel oils and fatty acids. While these can add complexity in small amounts, they can become oily, coarse, or off-putting in excess. Like the foreshots, we set this aside and add it to the next batch of low wines that goes into the spirit still.
Maturation
The last part of the process is the longest, where we transfer the new make spirit to oak casks for maturation. This ageing process, which by law must last at least three years in Scotland, imbues the whisky with its distinctive character. Many distilleries age single malts much longer than three years; some age for several decades.
The interaction between the spirit and the wood casks contributes to the complexity, colour, and depth of the whisky. For example, our Kilmory expression is entirely matured in first-fill bourbon barrels, which gives it notes of vanilla and cream. We also take this spirit and finish it in Oloroso sherry casks for 6 months to create our Corriecravie expression, highlighting notes of sweet spiced berries, dark chocolate and hazelnut.
We're also exploring the use of many types of casks for finishing, such as palo cortado, tequila, tokaji and rum.
Lagg Distillery whisky tour
If you are interested in learning more about what we do at Lagg, then come and join us for a whisky tour. Our guided tours take you through the whisky making process, from grain to glass. You’ll see our copper pot stills in action and learn how we craft our signature range. You’ll also get the chance to sample our core and limited edition expressions.