Attenuation is a technical term used during the process leading up to distillation. It is possible to measure the decrease in specific gravity over the course of fermentation. Our stillmen and mashmen will take the specific gravity of the worts (that’s the sugary liquid that comes from the mashtun) when the washback is first filled. Let’s say the figure they arrive at is 1.055. Measuring the specific gravity at the end of fermentation will give a different figure, lets say 0.998. This would mean the attenuation would be said to be 57 degrees. For every 100 litres of worts attenuating through 8 degrees, approximately 1 litre of alcohol should be produced.
During the course of fementation, the liquid changes it’s name – from the sugary “worts” that leave the mashtun into the alcoholic “wash” that charges the wash stills.
The picture of Lemmy stolen from the net is entirely gratuitous, but Lemmy has livened up many a turgid evening in his time. Attenuation when used in rock and roll means something rather different. It is a posh way of asking the guitarist to turn his Marshall stack down…. It does not always work. Legend has it that someone once asked the mightly Motorhead front man what he thought he would be sounding like ten years from now. His answer? “Exactly the same – only louder.”