> I just purchased a new refractometer, and was surprised that
> no calibration fluid was included.

Take it, a pocketknife, and an sterilized eyedropper to your local
hospital, and ask the floor nurse in recovery for some used-up
glucose solution IV bags to use as a "poor-man's calibration fluid".
If you explain what you are doing, and why, they will likely dig
a few up for you.

Slit open the bag(s) with the knife, use the eyedropper to
suck up droplets that remain, and put a drop on the
refractometer.  (Don't touch with your fingers.)  The bags
should indicate the percentage glucose, and these are made
to very tight standards, much tighter than you could hope to
approach with a home-brew mix.

...and in August, bring it to EAS, and calibrate with the
Honey Show judges, or ask Ann Harmon to check your
calibration.  I think she was born with a refractometer
in one hand.  :)

        jim