When to Finish

This 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 :
    ...with my Stillmaker type reflux still, I notice that the temperature holds steady until near the end of a cut. I should note that I use a digital thermometer that registers to the nearest 1/10th of a degree fahrenheit and refreshes itself every 10 seconds.

    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 ..
  • Segregate your distillate into 1L (or pint) bottles as you collect it. Work out which of them are OK, and which aren't; eg the first 2-3L might be fine, but you start noticing the tails in the last couple. Only keep the first ones for drinking, but put the other bottles aside. Either toss these in with the next wash as you go to distill it, or keep them from several runs, dilute 50/50 with water, and give them a run through the still on their own (see - you're not wasting it, just delaying when you get to keep it). This will allow you to really push the end of the run, as you won't be allowing it to contaminate your good drinking spirit (but don't get silly - stop when you can notice the fusels !).
  • Get a better still (eg more packing, taller column, with greater reflux) The tails won't appear until quite late in the run (eg may only have to put the last 0.5L aside, not the last 2-3 L).
  • Be patient - take the time & run the still with a higher reflux ratio (collect less, return more back down over the packing). Use more cooling water in the reflux condensor section.
  • The still needs to run smoothly, with even temperatures. Stop it surging - the distillate should be coming out nice & steady - either a thin dribble or separate drops. Somethings wrong if its coming in spurts ; more even temperature control needed, keep the packing clean (back-flush it after every run), make sure the packing isn't too tight, have the right column size for the amount of power you're putting it (not a real skinny column with heaps of vapour going up it), don't have cool breezes blowing on the outside of the column giving spot cooling (keep the column insulated)
  • Take the time to polish neutral spirits well. Get a batch ahead of yourself, and always have one sitting on carbon, until you need to use it.

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.
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