foreshots as "the low boiling point compounds that come out of the still first. They contain
acetone, methanol, various esters and aldehydes, and other volitiles. Foreshots are to be considered poisonous and should
be discarded." Whereas heads "come out after the foreshots, and are almost pure alcohol, except that they are contaminated
with trace amounts of unwanted cogeners ..." To get a really clean distinction between the foreshots and the heads, first
ensure that you've let your column equilbriate under total reflux, then hold the reflux ratio high, such that you remove the
foreshots only very slowly (eg 1 drip per second), thus allowing an equilbirium to be maintained at the top of the column,
encouraging the methanol to collect there.
If you're after making pure neutral spirit for vodkas or gin you may choose
to keep the heads (eg the next 250 mL-1L of spirits) separate from the following couple of litres (middle run) on the
basis of their taste. These heads can still be used to make liqueurs, whisky, rums, etc, or redistilled later if desired totally
neutral. The only problem with heads is their non-neutral taste.
The distinction between the various phases depends
on what sort of still you have. They will all tend to merge from one to the other. This is particularly the case with a pot
still, where you notice the temperatures always slowly changing as the distilling run progresses. Using a reflux still or
fractionating column will allow the various stages to appear more distinct, as the temperature will be more stable, due to
the more distinct seperation of each compound.
Running the StillFor neutral spirits. there are many different ways of
running a still to achieving the same results.
To get high purity, you require your column to be doing many redistillations.
To get enough redistillations happening, your packing must offer sufficient "theoretical plates". The HETP that you get from
packing depends on many factors, but includes the surface area, the thickness of the liquid spread out over it, and the ratio
of liquid to gas. As the alcohol in the pot depletes, in order to keep the same purity, you need more redistillations happening.
The usual way to do this is to improve the HETP by increasing the ratio of liquid to vapour (eg the reflux ratio)
its a ratio, you can do it either by increasing the amount of liquid being returned (eg increase the amount of cooling water
to through tubes/top condensors, or closing the offtake in a Nixon-Stone ), or by reducing the amount of vapour (by reducing
the power input to the boiler). Both will have the same result.
Just how much action is required depends on what the
column is like to begin with. If its a tall column, packed with something with heaps of surface area (scrubbers), etc, it
may already have enough redistillations happening in it to satisfactorily cope with very low alcohol input. Thus there would
be no need to adjust it much during the course of the run. You'd basically turn it on, set it and leave it (though you still
need to catch it right at the end).
If however the column isn't quite so great, you might need to do some serious readjusting
of the reflux ratio right through the run in order to keep it doing what you desire.
Likewise, with the tall column,
maybe you elect to run it heaps faster at the start (and not suffer any ill consequences), but then progressively turn it
back down as things progress. Eg - do you run it the whole run at say 10 mL/min offtake, and never touch it, or say start
at 50 mL/min and then slowly wind it back to 10 mL/min over the following hours.
None of these are wrong or right,
just different. So when you hear of guys doing 17hr runs, thats fine if it suits them. I prefer the latter of fiddling to
get the shortest time. Each to their own. With rushing, I have more "oops" happening - finding that I haven't been checking
it quite routinely enough, and that its just spent the last 10-15min at too high a temp. But I'm still happy with the final
taste, so thats fine for me. Others may shun my juice.
Choose for youself - try a run at a really slow offtake &
little control needed, and compare against a "hands on, push it fast" approach. Maybe choose the middle ground.
as to go to electronic control or not - its just a personal choice, based on if the smoother control is worth the cost, if
whether it will work for your style of operation & still design, if you dabble in that sort of thing, or if you prefer
the hands on and driving.
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.
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
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.