Measuring the Alcohol Content

Depending on the reflux ratio of your still, you can produce a product up to 95 % ethanol (190 proof). You can't drink it this strong (remember - ethanol can be poisonous); it needs diluting. Get a spirit hydrometer (or one for wine), measure the % alcohol, and dilute it down to around 40 % (whiskey) or 22 % (liqueurs).

When you use a hydrometer, make sure that the alcohol is at the right temperature. If the alcohol is still warm, it will be "lighter" than at the "standard" temperature (usually 20oC), and thus the hydrometer will sink lower in it, making you think that its got more alcohol in it. Wrong. This is where most of the claims of getting 97% purity etc come from - only 96.5% is possible without using a vacuum still, or by drying the alcohol (even then, if left in an open container, it will suck in moisture from the air and dilute itself back to 96.5%). Most hydrometers come with a chart for making temperature adjustments.

The instructions which came with my hydrometer advise the following corrections to the final specific gravity reading ...
TemperatureCorrection (g/mL)
10 °C -0.002
15 °C -0.001
20 °C none
25 °C +0.001
30 °C +0.003
35 °C +0.004

Pilch gives the following advice ...
    Measuring & Adjusting the Strength of Your Alcohol

    An Alcometer (as apposed to a Wash, Wine & Beer Hydrometer) is used to test the strength of your spirit. Additives such as flavouring and Liquid Glucose will distort the hydrometer readings. Alcometers should only be used to test spirit in the following conditions:
    • before any additives such as flavouring or liquid glucose are mixed.
    • at temperature of 16 degrees C or refer to the Temperature Correction Chart below. Taking readings of warmer liquids may damage your hydrometer.
    • The Alcometer is floated in the spirit to measure the alcohol content. As alcohol is thinner than water, the higher in strength the alcohol is, the further down the hydrometer floats. The reading is taken where the surface of the spirit cuts the scale of the hydrometer.

    Temperature Correction for Alcometer
    Temp / %V30405060708090
    10 2.472.39 2.20 2.071.911.751.47
    15 0.410.40 0.37 0.35 0.320.290.25
    20 -1.64-1.59-1.47-1.38-1.28-1.17-0.98
    25 -3.70-3.58-3.30-3.11-2.87-2.63-2.21
    30 -5.75-5.57-5.14-4.83-4.47-4.09-3.43
    35 -7.81-7.56-6.97-6.56-6.06-5.55-4.66

    Husker has included an Interactive Temp Correction Calculator in the Calcs menu. It allows MUCH more accurate detailed information than the above table

    Take good care of your Alcometer as it's very fragile. Wash and sterilize with cold water only.
    Prior to Carbon Purifying, the spirit should be watered down in strength to 38-40% by volume prior to drinking. It is very important not to make higher strength spirit.

    Litres collected x Alcohol strength / Alcohol strength required = Total litres to be made up to. e.g 4.5 litres x 45% / 40% = 5.06 litres.
    If you collect 4.5 litres of spirit and this measured 45% after carbon purifying, then multiply 4.5 x 45. Divide this by 40% and you will need to make the total spirit up to 5.06 litres with water. In other words add .56 of a litre of water. This is a rough guide only but a very good one to follow.

    Watering down the spirit to 40%, or less is very important as people unused to high strength spirit can easily overdose resulting in Nausea and in extreme cases death.
    LIKKER 'n' LEATHER, 9 Dutton Street Walkerston. QLD 4751,Ph 49592859     This page last modified Mon, 05 Mar 2012 08:07:08 -0800