What is a Hydrometer used for and do I need one?
A hydrometer is a simple device that largely resembles a
thermometer. It is used to measure the specific gravity of liquids, most often
beer or wine, and therefore shows you the degree to which the yeast is turning
sugar into alcohol. Hydrometers are usually made of glass and consist of a
cylindrical stem and bulb weighted with mercury or lead to ensure it floats
upright.
At the fermentation stage, the hydrometer becomes
particularly important. It’s the device that will give you an insight into how
well the fermentation process is coming along, and whether your beer or wine is
ready. A hydrometer can also alert you of any potential issues that arise,
allowing you to make any adjustments if need be. It could be the difference
between a spoilt and delicious brew.
Using a hydrometer is an easy, four-step process.
1. Take a sample and
insert the hydrometer
Once the liquid has cooled and prior to pitching yeast,
you’ll need to take your first measurement. The reading you get is referred to
as the OG, or original gravity.
To obtain the OG, retrieve a sample of the liquid and
transfer it to a testing jar or cylinder. The testing container needs to have
enough of the liquid in it to support the hydrometer. Place the hydrometer in
the liquid and allow it to settle. Wait until all air has escaped the liquid or
gravitated upward. It is recommended to centre your hydrometer and position it
vertically to get an accurate reading.
2. Obtain OG Reading
The increments of your hydrometer are there to show you
specific gravity points. The gravity reading depends on where the liquid
reaches; this is where it should occur. Record the number that is being crossed
by the liquid.
3. Calculate with
Temperature
Hydrometer readings are stated assuming a standard
temperature of 15 degrees Celsius. Knowing the temperature of your liquid is
crucial for an accurate reading. There are many online tutorials, tables and
graphs to help you calculate the gravity reading, like this one here.
4. Repeat process
Once the fermentation process is complete, take another
gravity reading. This will be the final gravity reading, which is also known as
FG. Don’t test your brew too often as you are exposing your beer or wine to
harmful bacteria and air, which can lead to a spoilt batch.
We have some inexpensive hydrometers
for sale over on our website that are perfect for use with beer, wine and
cider, helping you to create the perfect batch. If you would like some help
with your hydrometer or are looking to find more information, don’t hesitate to
get in touch with a member of the Vigo Presses team by visiting our contact page or
calling us on 01404 890 093.
