As you will recall the malted, kilned barley had just been ground to a grist!
One tonne of grist is mixed with 4000 litres of water at 68deg C through the mashing machine into the mash tun.
It is left to sit for 25 minutes and drained away into a washback. Then a 1700 litre second water is added at 80deg C. This is also drained away to the washback resulting in 5400 litres for fermentation.
When a steady temperature of 20c is achieved, 15kg mauri distillers yeast is added to start the fermentation. This lasts for around 48 hours but can last up to 80 hour if the phenol content is much higher. Once the fermentation is complete the wash will be 7-8% abv. (And quite tasty i'll have you know!)
Half the washback is charged into the wash stilll (2700 litres). One third of which will be collected as low wines. It is heated and starts to release alcohol vapours at around 80deg C. It is run until the remaining alcohol is about 1%.
The low wines, and feints from the previous spirit run are charged into the spirit still at an average strength of 23%-24% and are heated to 85deg C. The resulting vapours still contain impurities and a "centre cut" of the collected spirit is taken.
The spirit is routed through the spirit safe and its specific gravity is checked at regular intervals to ensure only the "centre cut " of the spirit is taken. Spirit is run through until its ABV is 73% then the flow is switched over to the ISR or intermediate spirit reservoir (below) and it is switched back at 60%. Kilchomans lower cut point however is at 65.5%.
The tasty spirit is then pumped accross the courtyard to the filling resrvoir in the warehouse. Prior to filling the spirit is reduced in strength to 63.5% by adding water. 63.5% is apparently the optimum ABV for filling a barrel according to most distilleries. Bruichladdich differs on this point, and their policy seems to be 'add the full strength spirit to the casks'. ie why store water in your warehouse? But that's a whole other post!
Finally, here is some handsome fellow filling up a 500 litre sherry butt with tasty Kilchoman raw spirit with a gravity fed hose. Interesting facts...........(1) There was at least 20 litres of sherry in the barrel prior to filling so it's easy to see how the barrel and contents impart some flavours to the whisky.........and (2) it's final weight was.....552kg.
If you want to do a weeks work experience at Kilchoman look here.
You 'work' five mornings then you are free to do your own thing in the afternoons like explore the distilleries or drink your way to better health at Duffy's in Bowmore.
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