Originally Posted by Johnd170
You can use a vinometer. Works really well for finished wine.
A vinometer is a nifty little gadget. I'd never heard of one until now. I didn't watch the video so it may have already covered their limitations.
The vinometer is calculated on the basis of pure alcohol and water solutions, whereas wine is not a pure water/alcohol solution and the accuracy of a vinometer can not be relied upon.
Sugar interferes with the interfacial effects that a vinometer's action relies on and hence the method can only be applied to dry wines.
Similarly other components in wine can also interfere with accurate measurements