Hydrometers

[chadspad]

Can someone explain how a hydrometer works please? More specifically, I would like to know how to calculate the percentage of alcohol I have got at the end product.

My hydrometer has a potential alcohol % section that goes from 17 to 5 then sweet, medium & dry. If it reads dry, does this mean it is only about 2% alcohol?? I am confused

Thanks Wendy

[The Chili Monster]

Unlike what it's name suggests, the hydrometer measures the amount of sugar in a solution. As the fermentation proceeds, more sugar is converted to alcohol (You may notice on racking that the wine is not as thick as when you began the fermentation process) and so, if you know the original gravity, you can calculate the end gravity by simple subtraction. This is the most simple way of using a hydrometer.
Therefore the dryer the wine, the lower the specific gravity (or higher the abv), and vice versa.
Most hydrometers are supplied with a chart to help you work out the abv of your wine. Note, though, that you need to adjust slightly for temperature.
As I wrote above, this is the simple use. Seasoned hobbyists and professionals alike choose not to add all of the sugar to the must in one hit, rather gradually and more precisely, in steps. This makes it easier to obtain the desired final abv, plus prevents problems of over sweetness, which are more difficult to remedy later on.
Winemaking need not be so scientific (a first career choice leads me down the analytic route) and you can make good wines without gadgets. If you do want to become more serious in your winemaking, then I suggest you get a copy of CJJ Berry's First Steps in Winemaking
Hope this helps.

[chadspad]

Thanks for your help! Gonna have to get a copy of that book, its mentioned such a lot.