tubby_shaw
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How to use your hydrometer.
A hydrometer is an instrument that measures the density of liquid.
Below is a pic of a hydrometer measuring the density of a sugar solution, in a trial jar.
As brewers we are interested in the amount of fermentables (sugars) that are in solution in our beers wines and ciders.
The specific gravity of plain water will read 1.000, as sugar is dissolved into water the gravity increases, 25g of table sugar dissolved in 1 litre of water will result in a specific gravity of 1.010
This is the specific gravity (SG) of the wort (Beer) or must (Wine).
The more sugar that is present then the denser the liquid will be and the higher the hydrometer will float, this is how the specific gravity can be read from the scale on the stem of the hydrometer.
To read the gravity of a liquid, place a sample in your trial jar and check the temperature of the liquid. Hydrometers are calibrated to a specific temperature. Don't worry if the temperature is different you can use THIS CALCULATOR to get the correct reading.
Making sure that the hydrometer is clean, lower it into the liquid and give it a quick spin to dislodge any bubbles that may have formed on the hydrometer as this will give a false reading.
Looking horizontally across the surface of the liquid, read off the number on the scale that corresponds with the true level of the liquid and not the meniscus, see the image below.
To check that your fermentation has finished take two separate gravity readings 24 hours apart, if they are the same and within your final gravity target then fermentation has finished.
An estimate of the alcohol content of your brew can be calculated by making a note of the SG before fermentation begins and a note of the SG when fermentation has finished.
Ignoring the decimal point subtract the finishing gravity from the starting gravity and divide the result by 7.45.
As an example a wine has a Specific gravity of 1.080 before the yeast is pitched, after fermentation has finished and the wine has cleared the Specific gravity is 0.995, so
1080 - 995 = 85
85/7.45 = 11.4
or 11.4% alcohol by volume.
A beer has an initial gravity of 1.044 and a final gravity of 1.012, so
1044 - 1012 = 32
32/7.45 = 4.29
or 4.3% alcohol by volume
A more accurate calculator is available HERE
A hydrometer is an instrument that measures the density of liquid.
Below is a pic of a hydrometer measuring the density of a sugar solution, in a trial jar.
As brewers we are interested in the amount of fermentables (sugars) that are in solution in our beers wines and ciders.
The specific gravity of plain water will read 1.000, as sugar is dissolved into water the gravity increases, 25g of table sugar dissolved in 1 litre of water will result in a specific gravity of 1.010
This is the specific gravity (SG) of the wort (Beer) or must (Wine).
The more sugar that is present then the denser the liquid will be and the higher the hydrometer will float, this is how the specific gravity can be read from the scale on the stem of the hydrometer.
To read the gravity of a liquid, place a sample in your trial jar and check the temperature of the liquid. Hydrometers are calibrated to a specific temperature. Don't worry if the temperature is different you can use THIS CALCULATOR to get the correct reading.
Making sure that the hydrometer is clean, lower it into the liquid and give it a quick spin to dislodge any bubbles that may have formed on the hydrometer as this will give a false reading.
Looking horizontally across the surface of the liquid, read off the number on the scale that corresponds with the true level of the liquid and not the meniscus, see the image below.
To check that your fermentation has finished take two separate gravity readings 24 hours apart, if they are the same and within your final gravity target then fermentation has finished.
An estimate of the alcohol content of your brew can be calculated by making a note of the SG before fermentation begins and a note of the SG when fermentation has finished.
Ignoring the decimal point subtract the finishing gravity from the starting gravity and divide the result by 7.45.
As an example a wine has a Specific gravity of 1.080 before the yeast is pitched, after fermentation has finished and the wine has cleared the Specific gravity is 0.995, so
1080 - 995 = 85
85/7.45 = 11.4
or 11.4% alcohol by volume.
A beer has an initial gravity of 1.044 and a final gravity of 1.012, so
1044 - 1012 = 32
32/7.45 = 4.29
or 4.3% alcohol by volume
A more accurate calculator is available HERE