How to Use a Refractometer for Homebrewing
November 19, 2019
During the process of homebrewing, you’ll want to check the specific gravity of your beer.
Gravity is a term that refers to the total amount of dissolved sugars in water. Various tools can measure the gravity of your brew. Unfortunately, some of these tools will require you to use nearly half a pint of beer to test. That sample is the beer that you will have to lose as part of the testing process.
Many dedicated homebrewers are attempting to keep as much beer as possible while brewing. As more tools come to market, there are more efficient ways to measure the gravity of your beer that doesn’t require taking half a pint from your brew.
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A refractometer is a tool that many homebrewers use for measuring specific gravity when making beer. A small device, the refractometer is an optical tool that can measure the amount of sugar in your solution.
A refractometer will allow you to find the specific gravity of your brew without much waste from the sample. With less glass than other measuring tools, refractometers are one of the more durable tools for measurement.
A refractometer is a simple piece of brewery equipment that will allow you to easily and quickly take samples and figure starting gravities of your brew.
How Does a Refractometer Work?
A refractometer works by using refraction. Refraction refers to the change in the direction of a wave that is passing from one substance to another.
The most straightforward example of refraction is by looking at a full glass of water. When you view the glass from the top, the bottom of the lens may seem like it is raised higher than it is.
When you place a straight object like a spoon or a knife in the glass, the utensil will look bent as you view it from the side. The refractometer works on a similar principle.
When you place the sample of the wort – the liquid extract from the mash – on to the refractometer, the light that passes through it will refract at different angles depending on the amount of dissolved sugar in the sample.
The refracted light will brighten a scale with a range of varying wort densities. By looking through the eyepiece of the refactor, you are easily able to read the density of the wort from the scale.
What is Brix?
Brix is the sugar content that is in a liquid solution. Brewing alcohol is just the conversion of sugars into ethanol and carbon dioxide. Being able to calculate the sugar levels in wort allows brewers to figure what the alcohol content of the brew will be after fermentation.
The value of Brix is expressed as degrees Brix (°Bx). This value is based on a range of one to 100.
As brewers use their refractometer to measure the degrees Brix of their wort, they can estimate the potential value of its alcohol content by multiplying the value by 0.59. If the wort had a value of 17, the possible alcohol content would be approximately 10.03%
The value of the alcohol content is approximate as other factors also determine the efficiency of the fermentation. The conversion factor of Brix to potential ABV can range from 0.55 to 0.65.
Brewers will take sample readings throughout the fermentation process. Sample readings allow them to measure mash efficiency, recipe targets, the progress of fermentation, and when fermentation has finished.
Some brewers may prefer to take specific gravity or Plato measurements instead of Brix, but all units are used to measure the same thing. If a brewer takes a Brix measurement, it can be converted to specific gravity or Plato easily with simple calculations.
Before you begin using a refractometer, it needs to be calibrated, as many technical measuring tools do. Calibrating a refractometer is a quick and easy process.
Lifting the sample plate (sometimes called the daylight) will allow you to place a few drops of distilled water on the glass. Once the distilled water is added, the daylight plate is closed, and the water will spread across the sample plate. There must be no bubbles within the sample.
Refractometers are sensitive to the temperature, which will require the sample to be warmed to room temperature unless the model automatically adjusts for temperature.
Once the sample has reached the ideal temperature, the refractometer is held to the light to take a reading. Many refractometers will have a calibration knob that will allow the calibration setting to be adjusted. The refractometer should be corrected to say zero with distilled water on the sample plate. It may take a few tries, but once the refractometer is zeroed out, it is ready to be used.
After the refractometer has been calibrated, it is ready to be used in the beer-making process. The use of a refractometer in brewing is similar to the steps used for calibrating the tool.
The sample plate is opened once again for a sample of the wort to be added. The plate needs to be clean and dry. A few drops of the wort are placed on the sample plate. If the wort sample is hot, it will need to be cooled to room temperature (around 68 degrees Fahrenheit). The sample plate is shut, bubbles are released, and the refractometer is held up to a natural light source.
The reading of the refractometer is simple. The calibrated scale will show you the result through the eye viewer. The reading will likely be in degrees Brix. If the reading is in a different measurement, like RI (refractive index), many tools online assist in the conversion of one unit to degrees Brix.
While a refractometer is an essential tool in homebrewing, it’s not the only tool for measuring the gravity or Brix of a brew.
A hydrometer is a tool similar to a refractometer that will tell you the consistency of your brewing process. However, hydrometers are more susceptible to drawbacks that don’t happen with refractometers.
One of the main issues with hydrometers is the sample size needed to do a reading. When using a hydrometer, a brewer will need to pull a sample size into a graduated cylinder and then discard the sample to avoid contamination. The amount required to test will waste several beers’ worth of wort as it ferments.
Another benefit to the refractometer is less equipment. Hydrometers require a larger graduated cylinder and a sanitized thermometer. With a refractometer, only a dropper or pipette will need to be sanitized to pull a tiny sample.
Arguably one of the most significant drawbacks to using a hydrometer is the risk of batch contamination. With the larger sample sizes that a hydrometer requires, the fermenter will be open for a longer time. Leaving the fermenter open will increase the risk of contamination significantly.
Even with the threat of contamination from multiple samples, some brewers increase the risk of ruining their batch by leaving the hydrometer in the work when they take a measurement. While the thought is to avoid having to discard large samples, leaving the hydrometer in the wort will only increase the risk of contaminating an entire batch.
Many applications outside of brewing require the use of a refractometer. Refractometers come in four main types: handheld analog, handheld digital, Abbe or lab, and inline process refractometers.
Handheld analog refractometer
A handheld analog refractometer is the most traditional choice. This type of refractometer works by using lenses and prisms to project a shadow line onto a piece of glass that will show a shadow line on the instrument. The user will look through the magnifying eyepiece while holding the device to the sun to read the result of the measurement.
A digital refractometer works similar to an analog refractometer. The main difference between an analog and digital refractometer is the light source. Instead of using daylight, a digital refractometer will use its light from an LED in the device.
An Abbe refractometer is not used in the homebrewing process. While it is possible, While it could give a similar, accurate result, its size and operation are too large for home brewing. Most Abbe refractometers are made to stay on a benchtop in a lab.
Inline process refractometer
Much like the Abbe refractometer, the inline process refractometer is not used in homebrewing. The inline process refractometer is made to perform continuous measurement of a fluid through a pipe or in a tank.
With several refractometers on the market, it can be overwhelming deciding which one is the best for your needs. Below is a list of a few of the top-rated and most recommended refractometers in 2019.
1. RCYAGO Refractometer Brix 0-32
Based on reviews, sales numbers, and expert opinions, the RCYAGO Refractometer Brix 0-32 is one of the first refractometers that you should consider purchasing.
This handheld analog refractometer contains high-quality copper, solid texture, and a firm structure. Automatic temperature compensation technology will allow you to measure without having to let your solution sit to reach room temperature. This refractometer has no battery and is simple to calibrate.
2. Brew Tapper Dual Scale Refractometer
A second option for a high-quality refractometer is the Brew Tapper Dual Scale Refractometer with ATC. This device has an average 4.5 rating on Amazon with over 200 ratings.
Similar to the RCYAGO, it has an automatic temperature compensation allowing it to measure degrees Brix from 0-32 accurately. This refractometer comes in a sturdy and compact design and is an excellent tool choice for brewers of any level.
Other great refractometers include:
As with all important purchases, shop around, read reviews, and do independent research before making a final decision.
A refractometer is a simple instrument, but maintenance is vital to receive accurate measurements.
When servicing a refractometer, consider the following:
– Store the refractometer in a dry environment
– Try to keep the device at a consistent temperature, not going below 14 Fahrenheit or above 112 Fahrenheit.
– Only use one or two drops of a sample. Never submerge the instrument or hold it under a stream of fluid.
– Clean the measuring surface after each use. Cleaning will prevent cross-contamination.
– Thoroughly dry the device after each use.
– Handle the device with care at all times.
With proper maintenance, a refractometer will help brewers for years to come.
Serious Homebrewers Need a Refractometer
A refractometer can help take your brewing to the next level. With accuracy, simplicity, and a small sample size, refractometers are an essential tool in brewing. While there are other options available, a refractometer is a superior choice for serious homebrewers.
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