In the last “How do I do that?” we learned how to use a hydrometer and convert the resultant specific gravity readings to percentage alcohol by volume. This method is pretty accurate, and pretty easy as well as being relatively cheap in that hyrdrometers aren’t particularly expensive instruments. So why would anyone need to resort to purchasing a more expensive one that ultimately does the same thing?
The answer is efficiency.
Hydrometers — though relatively accurate — require a sizable sample of wort to take a reading. Brewers conscientious of sanitation know that it’s best to discard the sample once a reading has been taken. This wastes precious wort, especially in the later readings used to determine whether the beer is fully attenuated. Let’s say – conservatively – that a sample size uses three ounces. If four samples are taken, a whole 12 oz. beer is wasted. (more…)