A refractometer instantly reads gravity, in Brix and gravity, of unfermented wort or fruit juice by measuring the degree that light passing through the sample is bent. Unlike a hydrometer, only a few drops are required for a sample. To use, apply 2-3 drops to the prism face, close cover, and look through the eyepiece while aiming your refractometer at a light source.
Our refractometers measure from 0-32 Brix (with an accuracy of +/- 0.2 Brix) and 1.000 to 1.120 SG. They also include automatic temperature compensation for temperatures between 0-30°c, which eliminates the need to consult temperature correction charts.
Please note: the refractometer is not to be used after fermentation has started, light refracts differently through alcohol than it does water and sugar.
About the Normal Handheld Refractometer. The calibration just use for measure from 0%. Open the cover plate, drop one or two drops of distilled water on the prism surface , closed cover plate, press it lightly,then adjust the correct screw to make the light/blue boundary concide the null line.