13th October 2021 / by Hannah Thaxter

All whisky starts with water and barley - grind the grain, add water, stir, heat, ferment, distill. Easy. Guest writer  Hannah joined a late shift in the mash house and found out it’s not as simple as it seems.



A working museum

In an eight-hour shift in the mash house, a Mashman has a myriad tasks to complete. 

With 12 mashes a week and each mash taking about 9 hours they cover most processes in one eight-hour shift. 

I’m with Graeme Kirk, who’s done this solitary role for about eight years, after decades doing various other jobs. He leaps around the place  – taking the steps three at a time and hopping in and out of the mash tun like he’s vaulting a small stile. 

He’ll put up with eight hours of my incessant questions (some repeated several times until I’d “got it”) and my giddiness over simple things – the Heath Robinson contraption of string, pulleys, and float which shows how much water is in each brewing tank is my favourite.  

And still he politely insisits it’s no bother. 

The mash house and mill house here have changed little since the distillery was founded in 1881 – albeit we now use electricity rather than horses.  As Graeme says, it’s like a working museum.  

Cast iron rivets are shrunk and rounded by decades of thick paint, the iron plough and rake in the mash tun are the epitome of ingenious Victorian engineering. In the mill house the wooden ‘dresser’, the mechanical weighing and mill rollers, all belt-driven, would look quite at home in Beamish Museum. 

Maybe I’m being romantic – parts will wear out. Perhaps original elements have been replaced, albeit sympathetically. But the process I’m witnessing is real. It’s manual. It’s analogue. There isn’t a computer in sight. 

Keeping things ship shape

The mash house leads through to the tun room where the washbacks are housed, quietly bubbling away. That leads in turn to the still house where the alcohol is intensified in high copper stills to make spirit for whisky. It’s all under one high roof with pipes linking one room to another, gravity drawing things downhill towards the shore. Valves and levers and stairs and unidentifiable bits of machinery bulge out here and reach up there. 

It reminds me of being below-decks on a ship – this is the engine room of the distillery.

Some of the metal stairs are so steep they have grab rails either side just like going down into the hold. Every piece of equipment is named with a small plaque – Brewing Tank 2 Turnbull Grant and Jack, engineers, Glasgow 1881 (the cast iron name plate from the original brewing tank bolted on to a new stainless steel version); Worts Cooler (looks like a giant radiator from the front of a vintage tractor); Washback 4 (we’ll be filling this giant wooden tub later); Balance Drainer, an essential piece of kit to let you know the fluid levels in the mash tun. 

There’s always something making a noise – a hiss, a clank, a burble, a gulp, a shudder – and like elsewhere in the distillery, there’s a log to be filled in at every stage of the process. 

Graeme is captain of the watch, and keeper of the handwritten log this afternoon. 

Our shift begins at 2pm and will end at 10pm; night shift is 10pm to 6am and days from 6am to 2pm. The mashing week starts Sunday night at 10pm and ends on Saturday morning at 4am.  

On friday nights the mash tun is thoroughly cleaned then pressure washed. We’re dealing with live ingredients here – viable organisms which come alive with the warmth and the liquid and the yeast.  

All under control

The basic principle of mashing seems straightforward to grasp – I’ve seen plenty of beer being brewed back in my native Yorkshire. But there are so many checks and balances along the way, like getting the right mix of flour, middle and husk in the grist, or ensuring the perfect flow of grist and water for the mash, all the while keeping an eye on the temperature of everything.  

I ask Graeme: “What kind of things can go wrong?”. At that exact moment he bends over a valve wheel to open it and his glasses fall from his head and clatter to the floor below as he ruefully replies “plenty”. (Thankfully he laughed, and the glasses were none the worse for their fall).  

Indeed plenty of things have fallen into the washbacks, apparently! Things can overheat, clog up, or jam shut. Belts can snap, pipes burst and washbacks leak. The huge brewing tanks bearing the weight of 18,000L of water (about 4,000 gallons) vibrate ominously on their girders when hot.

You could run out of water before all the grain is in the mash tun or let through too much grain at first so it clogs at the bottom with water sitting on top. It could be too cool and won’t release its sugars. Or if you don’t have the Wort (the liquid resulting from mashing) at the right temperature for the particular strain of yeast it will ferment too slowly or will be killed off by heat. If the Mashmen (there are no women in this line of production – yet) didn’t keep an eye on the washbacks there’d be foam all over the place.  

Temperature is everything. If it’s warm outside then the water from the dam is warmer so you need less time to heat it. Overheat it and you’d have to add more water to cool it; add more water and you’d have a weaker mixture to go into the washbacks, lowering the alcohol content.  

Barely two hours in and my head was, well, mashed! 

Full cycle

We’re on Bairds Scottish Mainland Barley at the moment. It’s been malted to be “heavily peated” and is destined to be Port Charlotte whisky. 

Water from An Torran reservoir up the hill behind the Coultorsay warehouses is piped down to the distillery. It’s what fills the two huge brewing tanks – they look like giant silver immersion heaters. 4 gallons of water in each is heated by steam through a heat exchanger.

The first tank full will be mixed with the grist and put into the mash tun. It’s a rare example of an open-topped mash tun still in use, and as old as the distillery itself. 

A V-shaped plough on the brass bottom has curved rakes attached with arms arching above the mixture. It moves round and round like clockwork on a track on the inside edge, stirring up the porridge-like mix. A couple of full circles is all it needs each time. 

Seven tons of malted barley is mixed with the first water at 149 F. It’s left for about half an hour to soak, letting the grain release its sugars. Then the Wort is drained from the bottom through slim slits on the mash tun floor. It’s cooled and pumped away to the Washbacks to meet the yeast.  

For one mash there are four fills of water in the mash tun. The first two are drained into the washback and the second two go back into the brewing tanks. They’ll be the water for the next mash. Each time the temperature of the water must be slightly different, as is the length of time it soaks. 

When all four waters have been put through, the mash tun is emptied of the leftover grain. The plough and rake go round pushing it down four holes which have now been opened up in the floor. This is known as casting. What looks like wet bran falls down these holes through chutes to the draff house below. This draff is then blown up a pipe and dropped into a skip outside. When full it’s driven away to feed local cattle. 

It was at this point Graeme said he had to get into the mash tun to sweep out the last of the draff – I thought he was kidding. He wasn’t, and I wasn’t going to miss the chance to jump in and have a go myself! Getting out again was another matter, it’s about 10 feet deep… Then it’s wellies and waders on and give it all a good powerwash. 

There’s no break before the next mash goes in. A mix of hot water and grist splurges over the rake and plough, dispersing it so that it doesn’t all land on one spot of the mash tun floor, potentially damaging the floor plates and bending them out of shape. It also spits porridge-mix over anyone standing too close, as my tee-shirt testifies.

Grist to the mill

Once that’s steeping, we dodge the rain and dash across to the building next door – the mill house – to start weighing out and milling the grain for the next batch.

The rollers on the wonderful Victorian machinery have been calibrated to grind the barley to the perfect mix. The first set of rollers crack the grains and the second set crush them into flour. Grist is a mix of all of this – husks, middles and flour. But first the grain from the big hoppers (“malt bins”) has to be shaken through a wooden “dresser” to seive out any foreign bodies or stalks that have got mixed with the kernels. Then it is chugged along and into the Avery scales to be weighed in a “tip”. Each time the scale bin reaches the set weight it will tip the contents down into the rollers. For 7 tons we need 175 tips and each tip takes 79 seconds. Which translates to a couple of hours, during which Graeme keeps popping back to check that all is in order. With equipment this old and flour dust in the mix it’s wise to keep checking on progress. Every so often the Mashman has to check the consistency of the grist and recalibrate the rollers. 

There’s more measuring to be done though – the temperature of the embryonic liquid in the washbacks and the “gravity” – basically the viscosity of the liquid. This means lowering a metal cup down into the giant washback and pulling it up again on its string. It smells like weak warm beer. It is tested with a glass hydrometer which the mashman simply drops into the flask. It’s at 75 which is just what we want. 

Graeme is clearly skilled at what he does. The grist and water for the first fill finished at exactly the same time, the temperatures were always spot on. He’s unphased too when things go awry – when we turn on the water to fill the tank and the pipes bang and jump, or when the boiler temperature drops too low, or when not all the water came out of the mash tun because the little slits in the bottom were blocking.  

Patience and calm are needed here, and dedication. If you want a cuppa or a bite to eat, it’s in the mash house – you can’t leave this place unattended.  

I think it could be quite lonely? Graeme thinks not!  He’ll be happy when he can spend his next shift alone with his thoughts no doubt, without a flood of questions, warmed by the steam and comforted by the steady chug of machinery. 


Bruichladdich Distillery
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