Difference between alcohol meter and hydrometer
Many people think of a correlation between hydrometers and alcohol meters because they look the same. They think they only need to buy one and do some calculations to get two types of readings from a single instrument. What surprised us, however, was not the case. Hydrometers and alcohol meters are calibrated for liquids of different densities, so although they look the same, they are actually completely different.
If you want to determine the volume percentage or standard of alcohol, it can only be used in pure distilled spirits. It can only be calibrated to the density of pure ethanol. When you do this, there is your alcohol content at the intersection of the lines. Because water is more viscous than alcohol, more water means that the liquid is denser, and the alcohol gauge cannot sink that deep. But keep in mind that this only applies to pure distilled spirits that do not contain sugar or glycerin. Some commercial products even add a little sugar or glycerin, although it just gives it a bit of taste. You may be surprised when the commercial vodka you test accounts for 40% and the registration rate is only 36%. This is because they are using something from vodka to make it a little thicker, so the alcohol meter doesn't sink that deep and gives inaccurate readings.
A hydrometer is used to determine the percentage of potential alcohol before and after fermentation. Calibration is based on water density. If it is pure water, it means it will float at 1.000. The more sugar added, the thicker the mixture and the more difficult it is to sink. Suppose you are making sugar water and turbo yeast. Once sugar and water are mixed, the sugar becomes denser and the hydrometer will float higher in the liquid. As the fermentation progresses, as sugar is converted to alcohol during the fermentation process, the liquid will become thinner and the hydrometer will be deeper, so the reading of the hydrometer will also change according to the temperature. Will be listed on the right. Think about the response of molasses to different temperatures: the hotter the molasses gets, the thinner the consistency, and therefore the deeper the hydrometer.
Alcohol and hydrometers, they look almost the same, but they are not interchangeable.