Alcohol and Sugar Interferes with each other when Measuring Finished Wine with a Refractometer.

How accurate is your refractometer when alcohol is present? Can I measure R.S. [residual sugar] in wine? thanks

Alcohol and sugar interferes with each other when measuring finished wine with a refractometer. You cannot measure the alcohol content in a finished wine directly using a refractometer, nor can you directly measure the residual sugar content. There are however, a couple of tricks that you can use to determine alcohol content and residual sugar content using a refractometer. These methods and more are discussed in detail in our technical bulletin, “Using Refractometers to Increase the Efficiency of Vineyard Management and Winemaking.”