How to use a refractometer

Last Updated: 26.01.20

Refractometers are commonly utilized to measure the concentration of liquids. They can be used under an array of circumstances and in multiple settings, and that’s why we have decided to write this article and let you know how you can make the most of them depending on your application.

In a nutshell, a refractometer is an optical device just like the binoculars from this review are. It can somewhat be compared to a hydrometer and you can use it to measure the specific gravity of urine if you work in a laboratory, or of wort or beer, if you brew your own beverages. Unlike a hydrometer, such a gadget is more compact and, to some extent, easier to utilize. You only need several drops of the aqueous solution to determine its concentration.

There are several varieties of refractometers available out there, which is why we suggest you perform a refractometer comparison before choosing a particular model. Some come with their own light source while others depend on an external one in order to do their job. Most of those that rely on an external light source are more or less inexpensive, so you should consider them if you’re on a tight budget.

When it comes to letting you know the density of the aqueous solution you want to measure, most refractometers will let you know the reading either in Brix or RI, with the second standing for Refractive Index. Because word doesn’t have the same reflective properties as water to which you have added sugar, you need to utilize a formula in order to convert either the RI or the Brix index.


How to calibrate a refractometer

Calibrating such a device isn’t all that difficult, but you do need to use distilled water. Place several drops onto the sample plate and close it so as to allow the water to spread across the surface. There should be no bubbles as they can impact the result.

Most of the models that we have come across are temperature-sensitive, and what that means for you is that you should always make sure that the sample has reached room temperature before attempting to measure its concentration. Of course, there are several alternatives that can compensate for temperature if they’re automatic, but they do cost a pretty penny compared to those that don’t come with this feature.

Take the reading by holding your refractometer up to natural light. If you’ve used distilled water, as we have noted above, you should use the screw or the knob that the unit is outfitted with so as to adjust it to read zero.

If you intend to utilize the device for getting the density of wort, we recommend performing two measurements. One of them should be with distilled water and the other with wort whose specific gravity you know for sure. To do this, you can first get the wort reading using a hydrometer and then match it to that offered by the refractometer.

How to use a refractometer for beer brewing

Using the device per se is more or less simple as it resembles the calibration process that we have depicted above. Start by making sure that the sample plate of the refractometer is both dry and clean, and then add several drops of the wort that you want to use. One note that we have to make in this respect is that the temperature of the wort should not be higher than 68F so as to avoid getting inaccurate readings.

All you have to do then is close the plate, make sure that you check for bubbles, and then hold the device up to a light source. It is preferable to utilize a natural light source as it can help you get accurate results. The reading that you will take from the sight scale can be expressed either in a percentage or degrees depending on the scale you will use — Brix or RI.

Understanding that the gravity of the alcoholic beverage you are making differs depending on its fermentation level is the right way of going about things if you do not intend to be disappointed in your refractometer.

You’ll have to calculate the results either by using a spreadsheet or a specific tool. Keep in mind that the equation changes as the fermentation progresses and more alcohol is produced.


Understanding the Brix scale

The Brix scale can tell you the concentration percentage of your sample. Every time you attempt to get a reading of a sugar solution, you need to make sure that the Brix percentage matches the actual concentration. For that, you will have to utilize a scale. Fortunately, it can be found online.

For instance, the % Brix for cutting oils range from 0 to 8 while that of carbonated beverages can range from 5 to 15. Jams and jellies have a % Brix concentration of 60 to 70 while that of grapes and wines ranges from 14 to 19.

Understanding Refractive Indexes

Unlike their Brix scale counterpart, Refractive index readings depend on the temperature of the environment. At 25 degrees Celsius, the refractive index of acetic acid, commonly known as vinegar, should be 1.370. At 20 degrees Celsius, the RI of olive oil should be 1.471.

As is the case with the Brix scale we were mentioning earlier on, you have a wide array of scales and references available online, and even several formulas that can help you get the concentration of your craft beer.


Make the most of online resources

If you still can’t figure out how to use your device, we suggest you go online and do extensive research on the topic. Luckily, there is a myriad of websites and video channels that you can make the most of. In fact, we’ve come across several YouTube videos that you can use to calibrate your refractometer.

Finally, if your application involves the production of homemade alcoholic beverages, don’t be afraid to use specialized forums and get in touch with other beer or winemakers like yourself.



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