Best Refractometer

Extra virgin olive oil is approximately 71.5 BRIX (ranges from 71 to 72, so calibrating to 71.5 puts you close). The refractometer should have a BRIX scale reading as well as % water- that's what's usually used for calibration.

I bought one from Amazon (Ade Advanced Optics Brix Refractometer - 58-90% range) that works pretty consistently, and was less than $30. Make sure you buy one that has the right range for honey.

Dioptric fluid (used for precise calibration) can be expensive, but another trick is to buy a small amount, calibrate the refractometer, then immediately measure a bottle of olive oil. Once you know the exact measurement of that specific bottle of olive oil, you can use it to do calibrations very inexpensively.

Good luck!

(Note: even a decent factory calibrated refractometer still requires calibration in use, because the reading varies with temperature- you need to calibrate it for the temperature of what you are measuring. There should be a small set screw that you turn for calibration that moves the scale reading as needed to zero it in.)

sjj said:

Why do we have to put our trust in olive oil?
Isn't it ludicrous?

Click to expand...

Yep! It does seem a little funny to trust olive oil, but since there's a very specific refractive index standard that extra virgin olive oil needs to meet, it makes a convenient and inexpensive calibration fluid. There are lots of other options (glycerol, etc.) that could be used, but most people already have olive oil in their kitchen and few people have lab grade supplies lying around.

Here's the money quote: "Virgin olive oil is specified by the UN FAO in CODEX STANDARD FOR OLIVE OILS AND OLIVE POMACE OILS CODEX STAN 33-1981 (Rev. 2-2003) to have a refractive index from 1.4677 to 1.4705 at 20°C which corresponds to 71°Bx to 72°Bx."

Another thing that I should have mentioned about the Amazon unit is that the calibration instructions it comes with are for the wrong unit. Put a few drops of olive oil (or dioptric fluid) on the clean glass, flip down the hinged lid to "squish" the droplets into a nice consistent film, look through the eyepiece, then turn the calibration screw on the top until the boundary between the blue and the white zones is at 71.5 on the Brix scale for olive oil (or the desired Brix number if you are using calibrated dioptric fluid).