….but some spirits are bottled at 46% abv!!!

A lot of people harp on about chill filtration in spirits, personally I’d rather my spirit to be not to be chill-filtered, but almost everyone glosses over the 46% abv fact that usually comes with it. They just accept it’s part of the package but don’t know why. It’s likely it is because spirits can go cloudy under 46% abv when temperature drops, unless they are chill filtered, so once you’re over 46% you don’t need to do it. Any other reasons for 46% though? You bet:

[Entering geek mode] Some time back I was looking into interesting factoids around aged spirits, as one does when one is an enthusiast and has a bit of spare time. One of the most interesting pieces of information I found came from a study in thermodynamics (“Rheological study and thermodynamic analysis of the binary system: Influence of concentration” by R. Belda et al).

Basically (very basically!) ethanol is thin – that’s what comes out of the still. Water is thin – that’s what they mix with the distillate to get the spirit to bottling strength. The more ethanol there is in a water/ethanol mixture then the thinner the mixture, likewise the more water there is in the same mixture then thinner the mixture. You would think that if the mixture was 50/50 then that’d be all good, right? Wrong.

Most spirits (in the UK anyway) are bottled at 40% abv, this is a nice figure, the mixture isn’t thin – if you swirl your glass you’ll get some beading – but when you start to increase the level of alcohol away from 40% something magic happens.

If you mix water and ethanol together the point at which the viscosity of the resulting mixture reaches its maximum is at 46% abv. 46%. And this holds true when tested at a large range of temperatures too. This is known as maximum viscous synergy. Any more than 46% and you start to get a thinning of the mixture again.

So, is this why you get “naturally” presented, or “craft” bottlings at 46% abv? In my view, yes – and most likely this added bonus of viscosity is just a pure accidental by-product of the fact that putting things to 46% abv means you don’t have to chill filter. Humans like texture, it makes a big difference to the way we experience taste. So there you go, a bit more of the science behind that particularly odd bottling strength of 46% abv. It truly is a magic number.

…………I might add that this all goes to pot when you start adding other stuff into your spirit, such as sugar. You can get a nice viscous mouth-feel by loading your spirit with sugar, but that’s going to impact the flavour delivery and it’s frankly cheating 🙂