Hi All,
I worked in the soft drink industry a number of years ago and refractometers
were the stanard for measuring the brix (percent solids) in a sugar
solution.  Check to insure the instrument reads "0" with distilled water.
That is all you should have to do.  Check several times before adjusting the
instrument to "0" with the calibration screw. If you have access to some
HFCS 55(High Fructose Corn Syrup that is 55% solids) check with that to
inusre the scale reads around 55-there is always some variation in tenths of
a percent above or below the 55.   Also, when your eye is at the eyepiece
have the insturment pointing at a downward angle not up toward the light.
The light must go through the cover over the prism to get a good and
accurate reading.

Coleene