Measuring alcohol content.

[Ronbo]

Thought I\'d open up a \'New topic\' heading.

I made a graphic to explain the proper reading of the scale of a hydrometer like the one I use. Which I found very confusing at first. I thought I was getting readings of 0.890 when, of course, it was 0.989.

Also I have a refractometer, which is very useful, but measures 0-80% w/w.

Anybody know how to make easy conversions to alcohol by VOL without resorting to higher maths!
Ronbo.

[Brewmeister]

The easiest method I use is:
1) pitch in sugar, dissolve. Measure SG.Lets say: 1090 as this is common with 6kg of sugar.
2) Let fermentation finish.
3) Measure SG. Lets say 985.
4) To calculate ABV: (1090-985) / 740

In this case: 105 / 740 = 14,1%
5) distill
6) enjoy

[Ronbo]

Hi Brewmeister,

The point of the graphic was to show that, on my hydrometer, the figures in grey are not marked, so the readings can be misinterpreted.

When using a pure sugar wash it is hardly worth taking an initial gravity reading, you know what it should always be for 25 Litres total, ie:
4kG 1.061 yielding 9.4%

5kG 1.077 yielding 11.8%

6kG 1.092 yielding 14.1%

7kG 1.107 yielding 16.5%

8kG 1.122 yielding 18.8%
Thats all assuming a perfect ferment. The formula I use is O.G. - F.G. x 129 = %
So in your example that would be 1.090 - 0.985 x 129 = 13.5%
But hey, let\'s not get too anal about the figures, if it tastes good that\'s what counts!

Ronbo.

[Ronbo]

My request about conversions was specifically; how to convert w/w% to v/v% for different concentrations of Ethanol / Water mixes. For example the beer brewing guys seem to rely on multiplying by 1.25, so that a 3.5% w/w would be 4.4% v/v (ish) But I don\'t think that holds up for higher concentrations, e.g. 60%.

Hence the original question. Yes I have a good alcometer, but it\'s sometimes convenient to measure from just a few drops with the refractometer.

Ronbo.