A hydrometer is a necessary component of the beer making process that allows homebrewers to adjust and predict the integrity of their recipe by providing accurate readings of the beer's sugar level as well as its specific gravity.
A blown-glass hydrometer has a narrow, lengthy stem and a weighted bottom that is bulbous enough to allow for flotation purposes. Inside the stem lies a scale that measures specific gravity, or the weight of the beer compared to the normal weight of pure water. Using this kind of measuring device tells the homebrewer how far along the beer has progressed in the fermentation process so that any necessary adjustments can be made before irreversible problems arise.
Using this device is a convenient and affordable way for homebrewers and winemakers to:
- *Approximate an alcohol percentage potential when yeast pitching is occurring
- *Estimate alcohol percentage by comparing before and after rates
- *Accurately determine the completion of the fermentation process or when it needs to stop
What is the Specific Gravity Scale?
Floating this device in plain water will give you a specific gravity of 1.000, which is near the top of the scale. Because the majority of hydrometers are made to reflect accurate readings at around 60 degrees Fahrenheit, water that is slightly cooler or warmer may show varying but similar readings.
Placing this meter into sugary fruit juice, or any other liquid containing sugar, will cause it to float higher than it did in plain water. For example, testing one gallon of water containing two pounds of dissolved sugar reveals a specific gravity rate of around 1.068. You can find this number by searching for the number 60 on the scale (which actually means 1.060) and determining at which tick mark the reading stops.
What is the Potential Alcohol Scale?
The potential alcohol reading of your beer is provided by the specific gravity reading. Rolling the meter around until you reach the PA scale gives you a nine percent PA reading. This means that if you fermented all of your beer's sugars into alcohol, the result would give you a nine percent alcohol rate (according to volume).
Using a hydrometer also allows you to discover the actual rate of alcohol in your finished beer batch by providing your first and last fermentation readings. Simply subtract the final fermentation reading from your first fermentation reading and you will know the percentage of alcohol in your beer.