Specific gravity or density is actually just a measurement of how dense (or thick) a liquid is. The density of water is 1.000. When you start your wine it is full of unfermented sugars that are quite dense so your specific gravity is high (between 1.075- 1.090). As the wine ferments and the sugars are changed into alcohol, the density of the wine drops steadily. A finished wine should be between .996 -.990.
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