De alcohol die er uiteindelijk uit komt delen door 25 = voorloop.

Ik pak 2% van het totaal in de ketel en gooi dat weg

Removing the Methanol

Be ruthless about tossing the first 50 mL (off a 20L wash) that you collect, as this contains any methanol (causer of hangovers - small quantities, or blindness - larger quantities). Even though I'm pretty sure I only collect less than 10mL at the methanol stage, I still discard 50mL, just to make sure. No need for penny-pinching when you're making 3L of the stuff, for less than $5. If you're using a potstill, you may need to increase this amount you toss up to 100-200 mL.

Jack writes ..I have tasted potstill alcohol that has been made both ways- when only 50ml (per 20L) was thrown out, the stuff was very sharp tasting. It became alot smoother when a full 100ml was thrown out at the start of the run.

This first portion is often called the "foreshots". They are different from the "heads". Ian Smiley ( http://www.home-distilling.com/ ) describes 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.

Bron:  http://homedistiller.org/distill