Alcohol Content for Washes where Sugar is present

Alcohol hydrometers do not work well in some washes that contain some residual sugars such as rum. This method will allow you to calculate the alcohol content.

All floating types of alcohol meters (hydrometers) rely on the density of the liquid being measured and convert the density reading to an appropriate scale such as the Guy-Lussac scale (alcohol percentage by volume - % ABV).

Also, each hydrometer (and alcohol meter in this case) has been calibrated to read correctly at a specific temperature called the calibration temperature.

With hydrometer type of alcohol meters, it is therefor important to note the following two influences on the accuracy of readings:

  1. The liquid being measured should ideally be at the calibrated temperature of the hydrometer (20°C in this case). Deviations from this temperature require a correction factor to be applied to the reading to get the actual % ABV.
  2. There should be not residual sugar (of any kind) in the liquid. Ideally the liquid should consist of ONLY ethanol and water. In practice this is not often the case. If (dense) sugar is present in the liquid it "cancels out" the (less dense) alcohol with a resultant wrong alcohol percentage reading.

It would therefor be correct to say that an alcohol meter (of the hydrometer type) will always provide wrong results when used in an water, ethanol and sugar solution.

Commercial wineries use an instrument called an ebuliometer to measure the alcohol percentage in solutions with sugar in. Unfortunately ebuliometers are quite expensive.

However, there is a method which the small scale distiller may use to determine the alcohol percentage, with a hydrometer type of alcohol meter, in a water, sugar, ethanol solution.

Thanks to Frank Theron of Rottcher Wineries that brought this method to our attention:

This method measures the alcohol content by volume of any wine,spirit,or beer,using a hydrometer, giving readings as accurate as an ebulliometer used by commercial wineries. The method is based on the research of Dr. William Honneyman,Ph.D."

  1. Measure the SG of the wine you wish to test. We will call this figure SG-1.
  2. Measure exactly one pint of the wine (500mL). We will call this the sample.
  3. In a enameled or glass pan, boil the sample down to about half it's original volume. This drives off some of the water, but all of the alcohol, because alcohol boils at a lower temperature than water. The sample now consists of water, residual sugar, coloring matter, acids and proteins - that is: all the non-alcoholic constituents of the wine.
  4. With distilled water or rain water, make the boiled-down sample up to exactly a pint again. Tap water is not recommended because, in some areas, it has a considerable dissolved mineral content which could affect your results.
  5. Cool the sample down to 60°F, or what ever temperature your hydrometer is calibrated for.
  6. Read the SG of the sample, we will call this reading SG-2. You will find it higher than SG-1 because you have removed the alcohol and replaced it with water.
  7. Subtract SG-1 from SG-2. The difference is called the Spirit Indication.
  8. Read the alcohol strength from the following table.
Spirit       Alcohol Strength
Indication - % by volume

 1.5 ------------  1.0
 2.0 ------------  3.4
 6.0 ------------  4.1
 7.0 ------------  4.9
 8.0 ------------  5.6
 9.0 ------------  6.4
10.0 ------------  7.2
11.0 ------------  8.0
12.0 ------------  8.8
13.0 ------------  9.7
14.0 ------------ 10.5
15.0 ------------ 11.4
16.0 ------------ 12.3
17.0 ------------ 13.2
18.0 ------------ 14.1
19.0 ------------ 15.1
20.0 ------------ 16.0
21.0 ------------ 17.0
22.0 ------------ 18.0
23.0 ------------ 19.0
24.0 ------------ 20.0
25.0 ------------ 21.0
26.0 ------------ 22.0

As an example:

SG-1 (SG of original wine)     = 0.995
SG-2 (SG of sample at stage 6) = 1.011

Spirit Indication = 1.011 - 0.995 = 16

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