>What percentage of the wash is methanol?
>How much distillate do I discard to
>be safe? If you double or triple distill do I need to
>discard some on the 2nd and 3rd go?
It all depends on what you have started with, how healthy your yeast is, and
how stressed the fermentation is. A young, healthy yeast, provided with
plenty of nutrients & kept at a constant temperature below 25C will give
less off-products than a stressed one. If you have a look at
Gert has a "flavour rating" out of
ten, showing how the flavour degrades as the fermentation temperature is
increased. Also affecting the amount of methanol is the starting material.
Sugar washes won't produce very much at all, you'll get more for those with
higher amounts of cellulose present (eg grains, grape stalks & skins), and
particularly more for those with heaps of pectin present, (eg berries).
Even so, you still wouldn't really count on more than about 0.1% present for
a typical case. This is where the guideline of throwing away 50-100 mL per
20L comes from - a generous allowance to get say 20mL out using a still
giving say 30-50% efficiency. If using a good reflux still, it will be in a
smaller volume, whereas if you're using a pot still, you'd probably head
towards the generous end. It depends on how generous you are with the first
"throw" on whether you need to do it for the 2nd & 3rd, eg if you only
tossed say 50ish on the first pass, then it may pay to lose a little of the
2nd, whereas if you're doing say 75-100 mL on the first pass, then the later
goes are probably fine as they are.