What is a refractometer

As indicated by the name of the refractometer, it’s a meter that measures the percentage of dissolved content in liquids by the called refraction of light. According to different usage scenarios, we can call it coffee refractometer, salinity refractometer, coolant refractometer, honey refractometer, glycol refractometer, urine refractometer, alcohol refractometer, etc.

Simply put, fruit farmers can tell how sweet fruit is by squeezing only a few drops of juice out of that fruit. Then, spread it out evenly on the surface of the optical instrument’s prism/glass. They can get the reading right off a screen when using FJD digital brix refractometers.


How do brix refractometers work?

Brix refers to the concentration of dissolved sugar in a solution. It is widely used in the food industry to accurately measure the sugar content of the products, e.g., fruits, soft drinks, honey. So how brix refractometers work?

As light passes through the liquid, it is diverted by the dissolved solids in the liquid. The more dissolved solids there are in the liquid, the more diverted the lights are. In the case of fruit sugar, the sweeter the fruit is, the more sugar is dissolved in the juice. Then the more lights will be diverted, and the greater the brix reading will be. Therefore, the reading of the brix meter will tell the grower how to ripen the fruit.

Refractometers measure, with only a few drops of solution, a wide range of readings. They include the urine specific gravity, the sugar concentration of fruit juice, the sugar content of a soft drink, coffee TDS, and so on.

Digital refractometer VS analog refractometer

They are both optical instruments. In the market, there are two major categories: analog and digital. The analog meter is designed, usually, with a tube of stainless steel, a prism and a plastic cover at one end, and a brix scale/dual scale in the eyepiece. It works when you spread only a few drops of solutions evenly across the prism without any bubbles in it, cover the prism up, and point the eyepiece to a light source. When light passes through the prism, it bends not only because of the prism, but also the concentration of the solution. The more dissolved solids there are in the solution, the greater the extent to which light bends. This is called refraction.

A digital refractometer, on the other hand, comes with a sample tank instead of a prism. It also reads refractive indexes of solutions and presents refractometer readings on the screen. The temperature affects the refraction index and the accuracy of the reading in the end. Both the analog the digital refractometers are capable of automatic temperature compensation ATC. Some people also call it automatic temperature correction. So they can present consistent accurate readings even if refractometers measure in different temperatures.

honey refractometer

How to use the FJD refractometer Air/Pro/Ultimate

Make sure the sample tank at the top of the brix meter refractometer is clean, dry, and residue-free.

Press the blue button in the middle to switch on the brix refractometer. Fill up the pool with drops of fruit juice or the solution you’d like to measure. Make sure it’s bubble-free.

Press the blue button again and the screen will tell you a digital handheld refractometer reading within just 2s. FJD cutting edge optical refractometers have automatic temperature correction to ignore the effect of temperature.

Hooray! There you have it. You have just gotten your first brix reading. FJD refractometer Air/Pro/Ultimate have wide range of 0-32%, 0-55% and 0-95%.

How to clean the FJD refractometer Air/Pro/Ultimate

Press the blue button in the middle to turn the meter off.

Grab a tissue and soak up the liquids.

Get rid of the remaining sugar content with a glass of water. Some drops of distilled water are perfect, but tap water will work as well.

Dry the instrument up with a second tissue.

Note: You want to clean the whole sample tank up until the glass reflects. The cleaner the pool is, the more accurate and consistent the readings will be.

glycol refractometer

Salinity Refractometer Measuring

How to measure salinity

It’s important to measure the amount of salinity since it matters. To get the accurate salinity, you will want to use a salinity refractometer. Here is how it works. The dissolved solids in any kind of liquid bends lights. The more dissolved solids there are in the liquid, the higher the refractive indexes will be. A salinity refractometer measures the solutes of the solution in your fish tanks. It determines the brix scale water content and solutes content (sodium chloride).

Using the eyepiece may not get accurate salinity. Your eyesight will interpret the readings. But the digital handheld refractometer may help, easily, quickly, and accurately.

After cleaning the sample tank, you suck up the water sample from fish tanks with a pipette. You drop the liquids onto the little pool and make sure it has no air bubbles in it. Then you press the blue button of the salinity refractometer. Within two seconds, an accurate reading of SG will appear on the screen, telling you the salinity of the water sample.

What is salinity

Salinity refers to the saltiness of the water — the total amount of salts dissolved in the water.

Salinity for saltwater aquarium hobbits is probably the first thing they should learn and keep an eye on moving forward. Maintaining the right salinity in the saltwater aquarium is important. It contributes to the healthy growth of those little lives in the ecosystem.

If you want your aquarium to thrive, the right salinity should be the first thing to check off the list. You can measure salinity either by ppm or specific gravity. And the proper range for a healthy seawater aquarium should be 1.023-1.028 (specific gravity) or 34-36 (ppt). Hype or low salinity causes aquarium lives to suffer.

Things you need to know

Something worth mentioning: the FJD Air/Pro/Ultimate comes with a mobile App. It has built-in models for measuring various solutions, including saltwater. When you open the app, switch to the salinity model, the reading table will have a percentage on top and NaCl (sodium chloride) at the bottom.

Things to keep in mind: Use distilled water to calibrate the refractometer and clean it. Dry up the device after measuring and be sure there will be no residue anywhere on the profile of the instrument — saltwater is corrosive after all.

coffee refractometer

Why does coffee TDS matter

When you brew coffee, the coffee TDS total dissolved solids serve as one of the yardsticks. You get to control the extraction yield, coffee tastes, and the quality of the coffee as a whole with it. With a TDS meter, you can calculate the extraction – how much of the solids are dissolved in the beverage or how extracted the coffee is. The extracted coffee yield is expressed as a percentage. Let’s say 5 grams out of the total grounds of 30 grams make their way to the cup, the extraction yield would be 16.6%, or we can say it’s a cup of 16.6% extracted coffee. TDS is sort of like the numbers you can refer to in a coffee recipe to set the coffee concentration and make quality control. 18-22% is the ideal extraction range to get great tastes when you brew coffee.

In a commercial scenario, let’s say you’re in charge of coffee shops that offer specialty coffee. To make special coffee tastes across all locations consistent, you can refer to coffee TDS as a standard. Imagine the sheer amounts of specialty coffee to be sold a month, you can’t possibly taste each batch before delivery. You don’t want to lose the quality beans that you source from coffee roasters to poor quality control. Numbers help big time in this scenario.

What does a coffee refractometer measure? And How to measure coffee TDS?

A coffee refractometer or TDS meter is an optical refractometer measures the TDS (Total Dissolved Solids) of a cup of coffee. It’s pretty suitable for owners of coffee shops to make coffee recipe.

Before you measure the amount of coffee TDS total dissolved solids, calibrate the refractometer first.

Thoroughly clean it with the clean cloth that comes with it, but don’t scratch the glass of the sample tank. Fill the sample tank with a drop of distilled water, give the blue button a quick, and then long press. Wait for the system to “zero,” and when you have 0.00% on the screen, the process of calibrating your refractometer is done!

Cooldown a cup of coffee until it reaches room temperature. Suck up a small sample of the coffee with the pipette that comes with the kit. Drop the liquid into the sample tank. Press the blue button. The reading of coffee concentration will present itself within 2 seconds.

Cheatsheet: You can clean the FJD Air/Pro/Ultimate with clean water after the measurement and soak up the extra moisture with a tissue. When the glass at the sample tank has no residue on it and reflects, you have done your cleaning job.

Why use honey refractometer?

A refractometer has the function of measuring moisture in honey to determine its “sweetness”. You only need a few drops of honey to start the test. The higher the brix reading is, the more concentrated the honey is.

Capped honey refers to the cells on the frame that are sealed away with beeswax. Bees pass the nectar from mouth to mouth to bring the moisture down to somewhere around 20%. The worker bees cap the cells off when the nectar’s moisture level is as low as 18%. Bees also fan the honey to rid of extra moisture and seal them off because honey is hygroscopic – it absorbs water from its surrounding area.

Uncapped honey, if harvested, will be fermented because the moisture content of honey is above 18%.

Nectar flow or honey flow stands for the period when the sources of nectar are in full bloom. Bees will be collecting nectars during this period in abundance.

Before harvesting the capped honey, take out the frame and give it a gentle shake. If it leaks, that indicates the moisture in honey in the cell is yet too high – it’s not the right time for harvest. What is contained in the cells cannot be considered honey yet? If you’re impatient and harvest the watery stuff, which we don’t consider real honey, you’re going to end up with fermented “honey”.

honey refractometer

How to measure the brix reading of my honey

Beekeepers use a honey refractometer to accurately measure the moisture content of honey. There are two kind of this instrument in the market: the analog and the digital. An analog instrument is comprised of a stainless steel, a prism, a flap, and an eyepiece wrapped up in a rubber handgrip. To get accurate readings of the brix, you will need to evenly spread out drops of honey on the prism, cap it off with the flap, hold the eyepiece up and point the prism to a light source. You look through the eyepiece and get the brix reading off a brix scale built within the eyepiece. The thin line separating the scale will be your reading. So this is how refractometers work.

With FJD Air/Pro/Ultimate, you can, however, not only get the brix reading of the honey, but also measure the moisture content at the same time. To get the two readings at the same time, you will have to download an App called DiFliuid from Google Play. Connect the device to your phone via Bluetooth. Immerse the sample tank with honey to be measured, open the App, select the Honey model, press the blue button, and you will get a brix reading off the digital instrument and both the brix reading and the moisture content off your mobile phone App.

After the measurement, you can save the data for sharing or for future reference – The App logs your reading history.

How to calibrate your digital handheld refractometer

Now let’s start calibrating before using a honey refractometer and measuring moisture content in honey. Make sure there is no residue in the sample tank from your last measurement. Place a drop of distilled water in the sample tank, short and then long press the blue button to initiate the calibration. It shall be completed within a few seconds. It will be 0.00% on the OLED screen after finishing the zeroing. People who use analog refractometers also use olive oil – extra virgin olive oil to be specific, for calibration thanks to olive oil’s consistent properties. But that’s another story.

honey refractometer

What is a coolant refractometer

What is the difference between coolant and antifreeze? People are oftentimes confused about antifreeze and coolant. Simply put, automobile antifreeze has an ethylene glycol base. It increases the boiling point of liquid and decreases its freezing point at the same time. The extended range allows the coolant to not freeze in the winter and not boil in the summer. We need to dilute it before using it as a coolant. Propylene glycol and ethylene glycol are both used in antifreeze. But, ethylene glycol based antifreeze is dominating the marketer. Because it has a better performance of heat transfer than the propylene glycol based antifreeze. Fun fact: people use propylene glycol in the food industry, HVAC, cosmetics, etc. as it’s low in toxicity. Ethylene glycol, on the other hand, is toxic and suitable for closed systems where there is no risk of human contact.

A coolant or engine coolant is a mix of automobile antifreeze and distilled water, usually at a 50/50 ratio. (We are talking about the engine coolant here, not metalworking coolant.) The manufacturers differentiate coolants by color. So car users will not mix them up. It’s not recommended to mix coolants as they may cause damage to the cars. You may want to consult the manufacturer for detailed instructions on this.

How to measure the coolant’s freezing point

For most glycol refractometers in the market, they have three scales built in within the eyepiece. The leftmost one presents the reading of electrolyte, telling you the battery acid condition. The middle one measures glycol concentration, telling you the freezing point of the coolant. If your coolant is propylene glycol based, you read the scale of the antifreeze refractometer on the left, if ethylene glycol, read the scale on the right. The right-most scale measures the freezing point of your windshield cleaner.

Using a coolant refractometer to measure is basically a fluid testing process. You spread out the fluid evenly on the prism and close the flap and point the tube made of a piece of stainless steel toward a light source. Then, read the measurement by looking through the eyepiece. Top off or dilute your coolant as instructed on your pre-mixed coolant package if the reading is not what you desire.

How to measure glycol concentration digitally

When determining which brand or type of coolant to add, you’re advised to use a coolant antifreeze tester to check the freezing and boiling points first. The range between a coolant’s freezing point and boiling point indicates the quality of the coolant. The wider the range is, usually the better the quality of the coolant will be. Here are the four steps to measure the freezing point of the propylene glycol and ethylene glycol base coolant.

1. Clean the sample pool of antifreeze refractometer with a tissue.

2. Use a pipette to suck up some coolant to the coolant antifreeze tester.

3. Drop the liquid into the sample tank until the glass at the bottom is fully immersed.

4. Press the blue button in the middle and the result of this fluid testing will come out within 2s.

With FJD Air/Pro/Ultimate, you can determine the freezing point of the coolant within just a few seconds. The best part about the digital glycol refractometer is that it comes with an App that works with it. And it keeps track of the readings for your future reference.

How to use a urine refractometer to measure urine specific gravity

Urine is, essentially, a solution that contains salt, red blood cells, and protein. Kidneys are fed with floods of blood within the body and they filter out and rid the body of toxins from the blood. If the urine SG is low, that might be because you’ve been drinking a lot of water before the measurement. Or it might mean the kidneys are malfunctioning. They can’t filter out the toxins from the blood and rid them by way of urine.

The higher the SG reading is, the more concentrated the urine is with the waste. And that indicates that there is more stuff in the person’s urine. He/She might be dehydrated. The SG (density) of water is 1g/ml and the SG of urine falls within this range: 1.015-1.025g/ml. Diabetic people produce urine that is high in glucose levels. Because there’s too much of it in the body and there is insufficient insulin to deal with that amount of glucose. Thus, the body, which cannot deal with this much glucose, decides to get rid of the extras by way of urine. Because the sugar concentration is high in the urine, the urine is more likely to take on a fruity smell and appear foamy. The sugar in the urine is the building material of the foams.

How to measure urine specific gravity?

The way you measure the urine SG is the same as you do other solutions. Take a small sample of the urine. Cool it down to room temperature. Drop only a few drops of liquid into the sample tank. Press the blue button in the middle, and you will get the SG within 2 seconds.


How to use beer refractometer to measure alcohol content

Beer refractometer, some people also like to call it a brewing refractometer or alcohol refractometer. How to use it to measure alcohol content of the finished beer of your home brewing? The answer is that you can’t directly measure the alcohol content of your finished beer/spirit with such a brewing refractometer. But we can figure it out with the help of a formula, which you can find online. It requires a brix reading of unfermented wort and another after brew day. To measure the alcohol content of your beverage, you will need to figure out the original gravity and the final gravity. An alcohol refractometer is an optical instrument that can directly measure the specific gravity SG of a solution, beer included.

Calibrating your alcohol refractometer

On your brew day, before the measurement, make sure you calibrate your beer refractometer. How? Prepare a small sample of wort and a glass of water for cleaning after measurement. Hold the refractometer in your hand, and use a pipette that comes with the kit. And fill the sample tank with drops of distilled water. Short press and then long press the blue button in the middle until you see “zeroing” on the screen. That is the process of calibrating your refractometer. When the calibration is done, clean it up with a clean cloth and dry up the sample tank.

An analog meter is built with an eyepiece and a prism at the other end. If using it, you would have to look through the eyepiece to read the specific gravity scale. It is also likely to be right beside a brix scale if your optical instrument is a dual scale system. Hold the refractometer and read the specific gravity scale to make sure the line that meets the scale reads 0%.

Testing and Calculating

Now you use the instrument for measuring sugars in the wort. Use the pipette to suck up a small amount of wort to test the original gravity/starting gravity. It is the specific gravity SG of the unfermented wort. When the fermentation is done, if you don’t see the change in the refractometer reading of your sample, repeat the process as you were testing the original gravity/starting gravity. The original gravity and the final gravity are the SG of your final product. With it, you can then figure out the potential alcohol content of your finished beer with the help of a formula. We can describe it as ABV = (Final Gravity – Original Gravity) X 131.25. There you go. With this formula, you’re able to see how much sugar is converted into ethanol and you get a rough idea about the alcohol content of your finished beer.

Tips when use alcohol refractometer to measure the gravity of beer

Should I wait for the wort sample to cool to room temperature before doing the measurement? Yes. The digital meter comes with cutting edge automatic temperature compensation ATC. We still recommend you wait for the wort sample to cool to room temperature, then you measure for the sake of accurate reading.

You can use a hydrometer to measure the specific gravity of your beer throughout the brewing process. If so, we suggest that you don’t return the sample to the carboy or any container that you’re using. You will very much likely contaminate the precious liquid and end up with a spoiled batch. The hydrometer reading requires a much larger sample size in comparison with the small sample. So, if you use digital/optical refractometers, you lose that sample to the measurement. Also, please be clear that the hydrometer reading is gained by looking at it with your naked eyes. The accuracy is off than a digital meter.

Is there a wine refractometer? What if I am making wine, can I use a wine refractometer or is there such a device? Yes. You can use FJD Air/Pro/Ultimate for measuring sugars content of your grape juice before and after fermentation. Like what we have been doing with the home brewing process, brix reading is what we need to measure. You can use it to figure out the alcohol percentage of the final beverage.

beer refractometer