This jar looks a lot better sitting on your counter than the ones with the green plastic base. The crystal clear plastic makes it fun and easy to take a reading. This plastic is fine for beer wort, wine cuvee, and even undistilled whiskey mash since distillers ‘still’ need a triple scale hydrometer and a test jar to figure what percentage alcohol the yeast was able to produce. They use the proceedure shown below just like for wine and beer.
If measuring homebrew with greater than 25% (50 proof) alcohol you should really get a glass jar since ethanol is corrosive. But then they put moonshine in plastic milk jugs on TV don’t they? These cost much less than glass and are harder to break. For the purist we do also stock the glass trial jars, check our other homebrew items.
Determining the percentage of alcohol is indeed science but simple when explained: Sanitize the test jar and hydrometer together by putting sanitizer water in the jar and floating the hydrometer in it. It is OK to just keep them like that most of the time in a busy homebrew lab. Eyeball the “Potential Alcohol by Volume” scale right at the point it is level with the liquid. It and any other scales should read near zero with city water.
Before you pitch your yeast, re-use the sanitizer water by dumping it into something else you want to sanitize. Rinse the remaining sanitizer off the jar and hydrometer. Ladle some of your juice into the jar as shown below. Again float the hydrometer but this time take down your starting reading. If it says 14% write down 14%. Depending on your recipe this first starting reading will usually be between 8% and 18%. It is permissable to taste a few thimble full every reading…
Pour any remaining test liquid back into the batch. Rinse and sanitize your equipment.
Remember that starting reading % because you can take another reading at any time and subtract that current number from the starting reading and that is how much alcohol you have so far.There might be other scales on your hydrometer but my method is the easiest! There is an adjustment you can make for temperature but even at 84° it is tiny just .003 and can generally be ignored by most of us. I hope the method above helps.