Agriculture Reference
In-Depth Information
0.001, and if the temperature is between 75 and 80, add 0.002.
If the temperature is over 80, let it cool before measuring.
There is another method that I have never seen mentioned in
topics on winemaking, but I believe is superior even though it
requires the use of math. The method is as follows:
Buy a jug of distilled water at the supermarket. Leave it at
room temperature next to your primary fermenter so that it is
at the same temperature (by doing this, you won't need to
make temperature corrections later). Use a scale accurate to
within 0.01g to weigh an empty and dry 10ml graduated
cylinder.
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Then fill the cylinder with 10 ml of the distilled
water and record that weight. Finally, empty the cylinder, and
using a large sterilized syringe, fill the graduated cylinder to
the 10ml mark with wine must and record that weight. When
measuring volume, put your eye at a level with the markings
on the cylinder and fill until the lowest part of the liquid is
perfectly aligned with the 10 ml mark.
We now have three numbers. A is the weight of the empty
cylinder, B is the weight of the cylinder filled with distilled
water, and C is the weight of the cylinder filled with wine
must. The equation for the specific gravity is: SG = (C-A)/
(B-A). For example, my graduated cylinder weighs 37.65g.
When filled with distilled water it weighs 47.64g, and when
filled with a light sugar syrup it weights 48.57g. SG =
(48.57-37.65)/(47.64-37.65) or 1.093. Because both the
distilled water and the must were weighed at the same
temperature, temperature corrections aren't needed. Even
better, the amount of must used for testing was truly
tiny—less than an ounce. Discard the sample in the sink after
testing.
