Sugar Scale Hydrometer
Test Jar - The plastic case that the hydrometer is packaged in can serve as a test jar. Add enough of the beverage to be tested to the test jar (with the hydrometer in it) to make the hydrometer float. Gentle spin the hydrometer to release any air bubbles. The test jar can now be held at eye level so that a more accurate reading can be determined. The reading is where the hydrometer breaks the surface of the liquid that is being tested.
Specific Gravity Scale - range 0.990 to 1.120 - A hydrometer allows a brewer/winemaker to measures the weight of the wort/must in relationship to water. The weight of water on the specific gravity scale is 1.000 at 60° F. As you add sugar or malt, the specific gravity will be increased, i.e. 1.010.
Beer - Starting S.G. (Specific Gravity) of most beers will be in the range of 1.040 to 1.055. The terminal gravity will usually range from 1.006 to 1.018. The higher the terminal gravity the more body, (mouth feel) the beer will have.
Wine - The starting gravity of wine is generally in the range of 1.070 to 1.100. The terminal gravity at the completion of fermentation should be in the range of .990 to 1.000. The lower the terminal gravity, the dryer the wine will be. A dry wine may be sweetened to desired level of sweetness once it has been stabilized.
Sugar Scale - range 0 to 40 ounces per gallon - This scale will indicate exactly how much sugar is in your beer/wine per gallon prior to fermentation and can be used to determine exactly how much additional sugar should be added to bring it up to a specific alcohol strength.
Potential Alcohol Scale - range 0% to 16% - The potential alcohol scale indicates how much alcohol will be produced if ALL the potential alcohol is converted into actual alcohol.
Determining sugar needed to produce a finished wine of a determined alcohol level. Determine the specific gravity of the must without any addition of sugar. Lets say your specific gravity is 1.050 after the addition of all the fruit and water that's called for in your recipe. This approximates 7% potential alcohol and 18 ounces of sugar per gallon on the sugar scale. Since that is insufficient alcohol for your wine lets say we desire to increase the alcohol to 13% potential. Looking at the sugar scale indicates that 34 ounces are needed to achieve that level of alcohol. Now, we need 34 ounces and we have 18. Simple subtraction indicates that an additional 16 ounces will give us the desired 13% alcohol.