Calibrating a Refractometer

Nectar is pretty much like water when the bees bring it into the hive. They have to evaporate it down to at least 18% moisture before it becomes the magical thing we call honey — because that’s the point at which it won’t ferment. (Technically, honey be can 20% moisture, but 18% is in the safe zone.)

A refractometer is sort of a portable microscope we use to determine the moisture content of the honey after we’ve stolen it from the bees — essentially checking to see if all the nectar has dried up.

El cheapo refractometer ($24 Canadian) for testing moisture content of honey.

Moisture content is usually only a concern when providing honey for public consumption. Like many beekeeping gadgets, a refractometer probably isn’t necessary for the typical backyard beekeeper. But I guess it doesn’t hurt to have one around.

Refractometers range in price from $20 to $500. Most beekeepers I know seem to get by with the cheaper models, which are probably knock-offs of the pricier versions. But they work.

The only problem is that el cheapo versions often lack the necessary components to calibrate the refractometer before using it — to make sure it’s providing an accurate reading. Calibrating a refractometer, especially after combing through instructions that have been translated badly into English, sounds more complicated than it is. But it’s really easy.

We just find some kind of liquid with a known moisture content, look at it through the refractometer, and if the reading matches the known moisture content, then no adjustments (or calibrations) are necessary. If the reading is off, we turn a little screw on the refractometer until the reading matches the known moisture content.

Refractometer calibration fluid that is supposedly 65% sugar.

Which brings us to another problem with the cheap refractometers: Sometimes they don’t come with any calibration fluid, or the included calibration fluid isn’t reliable. Then we have to use some other kind of liquid to calibrate the refractometer — and the winner is extra virgin olive oil, which supposedly has a “Brix” reading of 71.5%. Huh?

Yeah. A typical refractometer (at least the type that I see everyone using) provides two readings, a “Brix” percentage and a “Honey Water” percentage. Honey water is also called moisture or just water (crazy stuff, I know). The Brix scale — just to keeps this simple —measures the amount of sugar in the liquid. And apparently extra virgin olive oil is 71.5% sugar. That doesn’t make sense to me, either, but that’s the reading we should get from extra virgin olive oil.

Refractometer reading with extra virgin olive oil, which is supposedly 71.5% “Brix” (or sugar).

So when we pick up our cheap refractometer, all we have to do is put a dab of extra virgin olive oil into it, hold it up to a light source, and if the Brix reading comes out to about 71.5%, bam, we’re in business. If the reading is slightly higher or lower than 71.5%, we adjust the little calibration screw until the Brix reading matches 71.5%. Then bam, we’re still in business.

Here’s my video attempt at explaining all this, keeping in mind that this is not my area of expertise because I rarely use a refractometer.

Capped honey is fully cured honey, so as long as I harvest capped honey, I know I’m good. I also harvest uncapped honey. I shake the frames upside down. If nothing drips out, I probably have fully cured honey. If something drips out, it’s probably nectar and the “honey” isn’t officially honey yet. I personally have no problem harvesting honey with liquid nectar floating in it. (Someone who takes all of this way too seriously just yelled out, “Never!”) Under-cured honey tastes good, it freezes in jars until I’m ready to eat it, and I’ve never had it ferment on me or make me sick. I don’t sell it to the public, but me and my friends eat it all the time. It’s delicious.

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