Hydrometer Test

Given the fact that the Munton's IPA appears to have stopped slightly short of the target gravity according to the hydrometer reading, I thought I should test the hydrometer's accuracy. An accurate hydrometer should measure exactly 1.000 in pure water at 20 degrees C.

I filled a bottle with water from the hot and cold tap, and after more messing about than I think it should have taken, I finally had a bottle containing 20 degree C water. I popped the hydrometer in and took a picture...



The line visible around the water level is the 1.000 line. It was noticeable that this line is below the top of the bell of water gathered around the hydrometer, but (when trying to read it from above the water) it appears to be slightly above the true level of the water. I would have liked to have been able to test this in coloured water, so that I could more accurately see where the correct level is with an opaque liquid like beer, but of course mixing the water with cordial would have added sugar and invalidated the experiment.

This was only a very quick experiment, but it has been useful. It showed that the hydrometer is pretty accurate. I also think that it means I have been very slightly over estimating the gravity of my beer. I had assumed that the actual level I was recording would be just out of sight below the visible level but looking at this experiment I believe the level I should be reading should be visible.