Originally By Tony Ackland
When to FinishThis really depends on what your still is like - they can all be different. The general rule is to finish distilling when the vapour temperature near the condensor is around 92-94 ° C. Depending on how much of the "tails" you collect, your spirits will aquire a different flavour. If making a neutral spirit, you wouldn't want any tails present, so you'd finish sooner (around 82 C?), however if making a flavoured spirit, you'd want a trace of them present. Note that you can always collect the tails seperately from the "middle run", and redistill them at a later date to get the ethanol from them.
If your column is a very high purity one, you may infact find yourself finishing before 82 C, with only a small amount left to collect as tails after that.
If you're doing a flavoured spirit, eg a schnapps or whisky, often the "cut" to finish will be based on taste rather than by temperature alone.
One clue that you've gone too far is if the distillate takes on a white/milky appearance. This is because the fusels (propyls, amyls & butyls) are partialy/totally insoluble with the higher %alcohols. You won't spot them if you keep your tails separate, as they are soluble within their own family in a weak ethanol solution. You may spot them though by seeing if a drop on the end of your finger gives a sun glint, and/or feels well lubricated (the old moonshiners trick). You may also see a slight film/slick on the surface of the distillate if using a clear container. If you can see them, then you can probably smell them too.
Another indication that its time to finish is when the temperature begins to fluctuate a bit. Tarvus writes :
For example, near the end of the time the foreshots are exhausted and the ethanol begins running, the temp will fluctuate dramatically after having held rock steady until then. The same seems to happen at the end of the ethanol run. When I see the temp starting to get squirrely, I stop the run. Maybe I leave a bit of usable ethanol in the wash, but it's worth knowing the stuff I collect is pure! :)
Let the distillate drop cleanly into the recieving vessel, so that it splashes. This will help it lose any fusels that may be present. For the same reason, it is better that the distillate is still warm to the touch, not cold. Don't put the end of the tubing under the level of the liquid, as this will cause any fusels that might be coming out as vapours to condense (and taint the flavour).
Greed is a bad thing. This is what gets your mates saying that your spirits taste "off" (you stopped noticing a while back, but everyone else still comments). You are either trying to rush things (good distillate requires time & patience), or you're wringing the neck of the beast and taking the run too far. You can't get ALL the available alcohol out of the wash. The better your still (eg the more "theoretical plates" / smaller HETP it has) the better your chances, but you still run the risk of contaminating your clean spirit with the tails, and having it smell & taste bad. But heres a few things to try ..
A 20L wash (at 12%) should produce approx 3L of 75% ethanol via a basic reflux still, or 2.3L of 95% ethanol via a fractionating reflux still.