How To Moonshine

Fermenting &
Distilling Basics
Making Equipment
How to Make Moonshine Using Sugar How to Make Moonshine Using Grain Moonshine Recipes

The Hydrometer

A hydrometer is a very useful instrument used to compare the density of a liquid to the density of water. This comparison is called the specific gravity and it can be handy when making moonshine because it can tell us a few things we might find useful to know such as how much sugar is our sweet wort or if fermentation is complete.

A hydrometer is not a particularly fancy gadget nor are they expensive to buy. The best hydrometers are bought from homebrew suppliers as they are calibrated in a range useful for homebrewers. A hydrometer is usually made from glass and is little more than a cylindrical stem with a lead weight on the bottom to make it float upright. The hydrometer is lowered into the liquid and allowed to settle so that it does not bob up and down. There is a scale on the stem of the hydrometer and the correct reading is found where the surface of the liquid touches the scale. Simply read the number on the scale where the liquids surface touches it and you have taken a hydrometer reading.

The scales are different depending on the intended purpose of the hydrometer which is why we specifically suggest that a brewing hydrometer purchased from a homebrew supplier is the ideal. Most of them have a scale starting from 0.98 and finishing at about 1.150 where 1.0 is the specific gravity of water. This is the most useful range for measuring the specific gravity of your sweet wort or the fermented wash. Generally the decimal point is ignored in brewing circles, so 1.150 is 1150, 0.98 is 980 and so on.

You can even use the hydrometer to work out the alcohol content of a fermented wash, simply prepare the wort as normal and take a reading of the specific gravity before pitching the yeast. We'll call the first reading the starting gravity (SG). Once fermentation is complete take a second reading, we'll call this the final gravity (FG). The formula for calculating the alcohol content is ((SG-FG)/7.46) + 0.5 = ABV. So if we have a sweet wort that had a starting gravity of 1042 and a final gravity of 1006 the formula would be ((1042-1006)/7.46) + 0.5 = 4.82% ABV. A useful thing to know when developing moonshine recipes as it can help you to determine how much grain to mash in how much water and such.

The hydrometer can also be helpful in determining if fermentation is complete, particularly if your fermenter has not sealed for some reason such as a leaking O-ring or similar problem that prevents the CO2 bubbling through the airlock from being your guide. If you take two readings with your hydrometer at least 24 hours apart and they are the same then the conversion of sugars to alcohol has stopped and fermentation is complete. While fermentation is taking place the yeast is converting the heavy fermentable sugars into lighter alcohol and carbon dioxide gas. As this conversion takes place your wort is slowly getting lighter and this is reflected in the change of specific gravity. Once fermentation is complete the specific gravity stabilizes.