What Is A Honey Refractometer?

Holding a honey refractometer in front of a frame of honey

A honey refractometer is an essential piece of kit for beekeepers looking to sell their honey. Hobbyists can also use one to ensure their harvest is ripe and ready to store in jars.

This article provides a beginner’s introduction to honey refractometers. We’ll explain how this handy device saves a harvest from the beekeeper’s worst-case scenario – fermented honey that ends up wasted.

What’s a honey refractometer?

A honey refractometer is a handheld tool beekeepers use to measure the moisture concentration in honey. It provides precise data that ensures extraction timing is optimal.

This gadget measures the light refraction (refractive index) level of the liquid. While this may sound complicated, it’s physics 101. Light changes direction or refracts as it passes through a substance.

  • A higher concentration of solids results in higher refraction.
  • Honey with more pollen, sugar, and other solids affects the reading of a honey refractometer.
A refractometer isolated on white background with labels of the device's parts

Why do I need a refractometer?

A refractometer helps predict whether honey will stay fresh once jarred. High water content increases the chance of unwanted fermentation, while a low reading means it’s likely to crystallize but keep well.

Quick tip: Get our list of the best honey refractometers here.

Honey refractometers are a must-have piece of equipment for commercial apiaries selling honey. They help beekeepers adhere to strict guidelines to meet industry standards in the United States and many other countries.

While not compulsory for amateur beekeepers, they’ll also find the technology a game-changer. If you’ve got a frame or two that are partially capped, deciding whether to harvest may be a challenge. A refractometer takes out the guesswork.

What is the optimal water content in honey?

Honey typically contains 14-20% water content. While no exact water percentage results in perfect honey, beekeepers should target 16-18%.

Moisture contentAffect on honey
17% or lessNo fermentation will occur.
18-19%Large amounts of yeasts must be present for fermentation to commence.
19-20%Fermentation is likely regardless of yeast content.  
Over 20%Rapid fermentation is inevitable as yeasts will proliferate.

How does water get into honey?

Nectar collected by honey bees may have an initial moisture content as high as 80%. The hive’s worker bees reduce it by fanning their wings before capping the cells. However, humid or wet weather may increase the water content within capped cells.

Honey is hygroscopic, so it absorbs moisture from the surrounding environment. Uncapped and sometimes capped cells will allow water to enter.

Do hobbyist beekeepers need a honey refractometer?

Some beekeepers are happy to wait for the colony to cap their honeycomb cells. While this is a helpful indicator, sometimes bees don’t seal cells. The colony may choose to leave them uncapped and use the honey as a food source. Limited wax supply is another reason capping gets delayed. A refractometer is a low-cost measurement tool that lets you know when to harvest a frame.

An illustration of a row of honey jars and honey bees flying over the top

3 benefits of a honey refractometer

  1. Accurately measure water content to avoid the development of baker’s honey. This fermented substance has a sharp, yeasty acetic acid and needs discarding.
  2. Sell honey that meets legal requirements by checking your product has less than 21.0g of moisture per 100g. For more information on this topic, get an instant pdf download of the USDA Commercial Item Description document.
  3. An easy-to-use tool compared to other complex techniques like isotope ratio mass spectrometry, liquid chromatography (HPLC), anthrone spectrophotometer, and silver nitrate and a-naphthol methods. Source.

Types of Refractometers

Common types of refractometers include inline, laboratory, analog, and digital. Of these four options, beekeepers should choose between an analog or digital model.

Inline refractometer: Used for the continuous measurement of Degrees Brix in industries like beverage, food processing, chemical, metal, power, and paper processing. Source.

Laboratory refractometer: These are typically complex, expensive pieces of lab equipment used for chemical analysis. They are unsuitable for testing honey.

Analog: The beekeeper places a honey sample on the cover plate and prism, then views the result by holding it up to the light.

Digital: a sample is dropped into the well, and the device uses its own light source to calculate moisture content.

Commonly asked questions

What is the Brix scale?

The Brix scale measures the percentage of solid material in a solution. It works in reverse to a honey refractometer, so if a Brix reading is 80%, the moisture level is 20%. In a pinch, a regular refractometer that only calculates Brix can be used by beekeepers.

Does temperature affect refractometer readings?

Temperature fluctuations will slightly impact the refractive index. Most honey refractometers use Automatic Temperature Compensation to improve accuracy and allow for changes in heat.

Who invented the refractometer?

Ernst Abbe invented the refractometer in 1871 in Germany. He was an Associate Professor at the University of Jena during this time. Source.

Is there a manual way to check if honey is ready to harvest?

Beekeepers can manually check a frame with uncapped cells. Shake it and wait for the result: if honey dribbles out, there’s too much water, and additional maturing time is needed.

While a shake test is useful for hives with removable frames, designs like the Top Bar won’t tolerate this treatment. The comb may break off, so a refractometer is especially helpful in this situation.

Summing up

Bees work hard to make honey, so bottling it too early is something to avoid. Honey refractometers are a super-helpful measurement tool that take the guesswork out of deciding when to harvest a frame. They calculate the level of light refraction in honey to determine optimal extraction timing.

Honey with high water content is prone to fermentation, so ensuring it has around 16-18% is essential.

Experienced beekeepers may rely on intuition or the hive to decide when to harvest, but nothing compares to a scientific, data-driven approach. For a small investment, beekeepers get an easy-to-use device that provides answers in seconds. Refractometers offer peace of mind that the honey will keep well in its jar without becoming fizzy and sour.

Further research worth reading:

1. Moisture in Honey: Review of Chemical and Physical Methods: Oxford Academic

2. Some Comparative Data on Moisture in Top and Bottom Layers of Honey After a Year of Storage, as Indicated by the Vacuum Drying Oven and the Refractometer: Oxford Academic

3. Effect of Temperature on the Viscosity of Honey: Taylor & Francis Online

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