What Is A Honey Refractometer And How To Use It

A refractometer is a tool that measures the refractive index of a liquid substance. In other words, it measures the degree light bends when passing through the solution. It is used in many fields to identify the purity and concentration of substances in liquid samples.

A honey refractometer is an instrument that measures the degree light bends when passing through honey. This helps estimate the moisture content in the honey sample – giving beekeepers more certainty over the risk of honey fermentation and whether or not to apply corrective measures. 

How Does A Refractometer Work?

Most of us have heard of refraction and how light bends or changes direction when it goes through a liquid like water. 

Remember that experiment with a pencil or straw in a glass of water and how it bends as it passes through water? – this is called refraction, and it’s the principle under which refractometers work.  

Refraction happens when light travels from one transparent substance to another. Following the previous example, when light travels from the air into the glass of water, light bends because of a change of speed – light slows down when it travels from air into water. 

The degree of refraction or bending light is affected by the number of liquids or solids present in a solution or substance. So, a solution with more dissolved solids will bend differently than one with less. 

A refractometer takes the angle at which light enters the liquid and compares it to the angle at which light exits to calculate the refractive index. 

What Makes A Honey Refractometer Different?

As I mentioned before, beekeepers use the refractometer to measure how much water or moisture there is in honey. 

Given one of the main components of honey is sugar, honey refractometers use the Brix scale, which measures the amount of sugar in a solution. 

One degree Brix is equivalent to 1 gram of Sucrose in 100 grams of solution (or one percent of sugar). 

While you can use other types of refractometers, you might want to make the task easier for yourself and get a honey refractometer. 

The difference is a regular refractometer will show the reading as a percentage of solids dissolved in water. Honey refractometers do the opposite – they give the measurement of moisture in solids. 

A honey refractometer has a reduced Brix scale. Instead of presenting values between 0-100% water in the sample, it will display a number between 10-30% water (equivalent to 70-90% solids in the sample).

These features will make testing the moisture in honey more straightforward – it will show you what you need, without having to make any additional calculations. 

Why Should You Buy A Honey Refractometer?

Not every beekeeper has to own a refractometer. However, it’s a handy tool when it comes to harvesting honey. 

The amount of water present in a batch or jar of honey will affect the rate at which it ferments. Therefore, it is crucial to measure moisture, especially if you plan to store your honey for a long time, sell it or give it away to other people. 

While there are many refractometers with a wide range of prices, it’s not necessary for you to buy an expensive one as a beekeeper. 

A handheld honey refractometer (around USD 20-USD 30) like this one from Amazon will be adequate for you to monitor the moisture in your honey. 

Types Of Honey Refractometers You Can Buy

There are two main types of honey refractometers you can get. These are analog and digital refractometers. 

The main difference is how the result is read. When using an analog refractometer, you will need to look through an eyepiece for the analog type and read the results from the scale presented. In contrast, a digital refractometer will show the reading on its screen. 

The other big difference you might find between these is the price. Digital refractometers tend to be more expensive. 

Which one you choose is entirely up to you. Both will serve the purpose – it’s just a matter of how much you’re willing to spend and which one you feel most comfortable with. 

Parts Of A Honey Refractometer

While a digital refractometer is simpler to use, an analog refractometer is more accessible in terms of price. Therefore, it tends to be the most common. That’s why, for this section, I’m going to focus on the analog refractometer.

  • Prism: This is the section where you place your honey. 
  • Cover: Clear lid or cover that protects the prism. 
  • Calibration screw: It is often covered with a plastic lid. With the help of a screwdriver and a calibration liquid, you will be able to calibrate the instrument by adjusting the screw. I’ll explain how to calibrate the device further down in this article.
  • Focus ring: This will allow you to focus on the image so you can see it clearly.
  • Eyepiece: This is where you will look to read the results. 

What Else Comes In The Box? – Analog Refractometer

Note: This varies according to the seller so keep this in mind when you are buying one. While some of these items can be replaced by everyday household items, you might want your set to include them – make sure you ask the seller what’s included. 

  • User manual: The instructions for the model and brand you bought. It will most likely include the steps for calibration and measuring and taking care of your refractometer. Sometimes the instructions may not be clear. That’s why, later in this article, I will explain how to use one.
  • Calibrating solution: A liquid that comes in a little bottle that will help you calibrate your instrument. 
  • Screwdriver to calibrate
  • Pipette dropper: This will help you take a honey sample and put it on the prism. If yours doesn’t have one, it doesn’t matter. You can still use other things for this, like a plastic spoon, a popsicle stick, or even your finger. 

How To Use A Honey Refractometer

Analog refractometers are easy to use but can be a little intimidating at first. So, here is a guide for you to know how to use your refractometer.

How To Calibrate A Honey Refractometer

Before you can start measuring your honey samples, making sure your honey refractometer is well-calibrated is vital. This will guarantee your readings will be as accurate as possible. 

Most refractometers will come calibrated from the manufacturer; however, it never hurts to check before using it. The screw can loosen up during transport or over time if you don’t use it too often.

What you will need:

  • Refractometer
  • Reference or calibrating liquid
  • Screwdriver
  • A source of light 

The reference liquid is a substance that has a known Brix reading or moisture content. If your set came with one of these, its Brix or moisture content will be written in the calibration instructions. 

Before You Start

  • Open the lid or cover and clean the prism with a microfiber cloth or lint-free fabric. I would recommend you do this every time you are going to use the refractometer. 
  • Another essential step before calibrating and using a refractometer is to ensure both the refractometer and the calibrating liquid have the same temperature (ideally room temperature: 68° F or 20° C). This is because temperature affects refractive index readings. 
  • You also need to keep the refractometer, the calibrating liquid, and the honey you will measure at the same temperature. For this, it might be helpful to do the calibration and measurement in a room you can keep at a constant temperature. 

Step By Step – Honey Refractometer Calibration

Lift the clear cover on the prism and add a few drops of the calibrating liquid on the glass. Use just enough to cover the entire surface of the prism, without going over the edges. 

  •  Close the cover and make sure there are no air bubbles by gently pressing down the transparent lid. 
  • Take off the cover of the adjustable screw and keep the screwdriver at arm’s reach so you can adjust it if needed. 
  • Take your refractometer and look through the eyepiece, while directing it towards a source of light
  • Move the focus ring until the scales and numbers become clear to you. You will see the background is divided into color blocks, most likely blue and white. 
  • The line dividing the two is what indicates the value in its corresponding scale.
Image showing the Brix scale
This is a representation of what you will see when looking through the eyepiece of a honey refractometer. The line separating the blue from the white indicates the value.
  • The substance you are using to calibrate already has a known or given Brix or moisture content value. As you look through your eyepiece, identify if you can read that given value or if your refractometer is showing a different one. 
  • If it’s different, you will have to calibrate your device by adjusting the screw while still looking through the eyepiece until the line between the blue and white meet the known or given value. 
  • Your honey refractometer is calibrated and ready to use. Clean the prism with a damp microfiber cloth or lint-free fabric, wipe it dry and cover it. Put on the cap or cover on top of the adjustment screw, and you are ready to go!

My Honey Refractometer Didn’t Include A Calibration Liquid. What Now?

What if your refractometer doesn’t come with a calibrating liquid, you ran out, or the Brix/moisture content is unknown? 

In this case, you can still use your tool and get accurate results calibrating with different substances that can be easy to find. 

The first thing you must keep in mind is that the substance you choose to calibrate should be compatible with the scale of your refractometer. 

Commonly, honey refractometers will have a 90-60 Brix scale or 10-30% water scale, which means, if you are using one of these refractometers, the calibrating substance you use should have a known Brix between 90 and 60 or 10-30% water content. 

For other refractometers with the full scale, you can use other solutions with Brix that go from 100-0 Brix (or moisture).

Calibrating Honey Refractometers With A 90-60 Brix Scale

Most people these days use olive oil in their cooking, given its increase in popularity, so it’s very likely you already have some in your kitchen. If not, you can easily find it in your local supermarket. 

Olive oil can be used as a calibrating oil. It won’t be as accurate as a calibration oil made specifically for this purpose, but it works well to test honey. 

According to the United Nations Food and Agriculture Organization (FAO), olive oil has a refractive index between 1.4677-1.4705, equivalent to around 70.9° Brix – 71.9° (as per ICUMSA standards).

Calibrating Refractometers With A Full Scale

The easiest way, and probably most accurate, to calibrate a refractometer with a full scale is to use distilled water which should read at 0° Brix. 

So, to calibrate, take one or two drops of distilled water and put it on your refractometer’s prism, and read the results against a source of light. If it doesn’t read 0° Brix, then you need to adjust the screw until it does. 

Calibrating With The Help Of An Already Calibrated Refractometer

This sounds like a Catch-22, right? But asking for help from someone who owns a calibrated refractometer can be a good option. Check with your local beekeeping club to see if anyone there owns and uses one.

Ask them to measure the Brix of a substance you can use to calibrate. That way, you can label it with its (now) known value and use it again whenever your refractometer needs to be calibrated again. 

How To Use Your Refractometer To Measure The Moisture Content Of Your Honey 

Now your refractometer is calibrated and ready to use, let’s move on to how to measure the moisture content of your honey.

Before You Start

  • Take your refractometer and honey to your extraction room, or somewhere you can control the temperature to keep it constant. You want both the refractometer and your honey to be at room temperature (around 68° F or 20° C).
  • Stir your honey well if it already sits in a jar or bucket. This will help to get a more accurate reading. The moisture content of honey taken from the top layer of a pot or bucket will be slightly different than a sample from the bottom. 

Step By Step

  1. Lift the clear lid on top of the prism. Use your microfiber cloth to make sure there is no dust.
  2. Take a couple of drops of honey with your dropper and put them on the prism and spread it on the whole area. Alternatively, you can stick your fingertip in honey and smear it on the glass. You only need enough to cover the prism area.
  3. Close the prism cover and squeeze gently to get rid of any bubbles.
  4. Take the refractometer to your eye and hold it in front of a source of light while looking through the eyepiece. Use the focus ring if you need the image to get clearer.
  5. You will see the background divided in white and blue with the border that separates the two. Most analog honey refractometers will have the water content scale and the Brix scale. Find the point where the line meets the water content scale and read the number. That is the water content or moisture of the honey you just sampled.
  6. Clean the prism and the clear lid with a microfiber or lint-free cloth.

Additional tips

  • I recommend you take multiple readings from the same sample and calculate the average, as a single drop might give a poor indication of the entire batch. This is particularly important if you are taking the sample from honey that has been sitting in a bucket or jar.
  • If you are taking honey directly from your supers before extraction, collect a sample from different parts of the honeycomb.
  • Making labels from masking tape with the moisture or the frame and date/time will help you track the progress if you are trying to decrease the moisture content.

How To Take Care Of Your Honey Refractometer

How you take care of your honey refractometer will increase its longevity and provide you with more accurate readings. 

Here are a few tips to make sure to take good care of it:

  • Always wipe your prism with a gentle, lint-free fabric. This will get rid of dust particles before you calibrate and use your refractometer. 
  • I recommend using a piece of fabric and limiting its use to cleaning your refractometer. That way, you can avoid taking particles and dust from other places onto the prism and potentially scratching it. 
  • After using, clean the prism and the transparent panel or lid with a moistened lint-free cloth. 
  • Make sure you put away your refractometer in its box after every use. 
  • Always close the clear panel or lid after you are done using the refractometer. Getting scratches on the prism will most likely affect the readings. 
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