How to Use a Refractometer to Brew Beer

Easy-to-Use Refractometers have become the new standard for beer measurement

ur love of beer, one of the oldest volume as determined through the world and were more cultural than products in the world, dates distillation. significant. O back some 7,000 years. From its humble beginnings as an industry, Primarily, measurement is about Later, around the turn of the 20th necessity warranted the creation of quality control. For instance, even century, it was found that various standards and methods for though beer in the US is taxed based on refractometers offered a superior measurement. The need for standards its volume, it is still industry best method for the measurement of sugar was driven by simple commercial practice for the beer chemist or brewer and alcohol compared to the requirements for accurately measuring to keep accurate records of beer hydrometer. Many of the units of the extract content of the wort for measurements. measure originally developed for determination of excise taxes. simplifying hydrometer readings were Development of a Cohesive adapted as refractometer scales. Most of these methods initially relied on the hydrometer, or some other Measurement Standard The most common international primitive measure related to specific brewing units of measure consist of gravity, to provide an indication of sugar Archimedes was the first to observe Brix, °Plato, Specific Gravity, Brewer’s or alcohol concentration. However, the relationship between the densities Points, Balling, and Total Dissolved refractometers have now proven of liquids sometime between 267 and Solids (See Appendix I). themselves to be useful tools for the 212 BC. Relying on the Archimedes brewer. principle, Hypatia of Alexandria, one of Common Beer

the first recorded female scientists, Measurement Terminology This paper is intended to help you invented the first hydrometer between get the most out of the refractometer 390- D. As an instrument, the that you currently own and to help you hydrometer was largely ignored until it For those new to brewing, there are decide what is most important in gained415 widespread A acceptance after some common brewing terms that are selecting a refractometer for future use. reintroduction by English scientist important to understand with respect to Robert Boyle in the late 17th century. beer measurement. These terms are Why Measure Beer? covered only briefly here. The reader In subsequent centuries, a series of should be familiar with these concepts improvements to the basic hydrometer and can find much more written about In the US and Canada, beer is were made with the intention of them in other publications. primarily taxed based on the volume providing a simplified system for the removed from the brewery. In Europe, measurement of specific gravity by Wort is the liquid extracted from the however, taxation is country dependent unskilled persons. These improvements mashing process during beer brewing. and is either based on the °Plato per related more to differences in units of Wort contains the sugars to be hectoliters (strength of original extract measure than to the actual principle of converted to alcohol during by volume) or, in some cases, the measurement. fermentation. alcohol content per hectoliter.

Different units of measure for Specific Gravity (D20/20) is the For most tax purposes, it is often specific gravity are akin to the relative density of a fluid at a reference nt difference in reporting temperature in temperature, relative to the density of alcohol by volume. However, in the UK, assumed that 1 °Plato ≈ 0.4 perce degrees Celsius vs. Fahrenheit. Specific water at a reference temperature. It can beer tax is calculated by multiplying units of measure became standard in a be measured using either a hydrometer hectoliters by the declared alcohol by particular beer making region or part of or refractometer with an appropriate

Copyright © MISCO 2014 scale, providing fermentation has not Alcohol by Volume (ABV) is simply Refractometers yet started. the percentage alcohol per volume of beer. A refractometer is an optical instrument designed to measure the Original Extract (OE) is the mass in concentration or mixture ratio of water grams of sugars in 100 grams of wort, Hydrometer vs. prior to fermentation, as measured on soluble fluids. It measures refractive the °Plato, Brix, or dissolved solids scale. Refractometer index, the speed at which light passes through a liquid. The denser the liquid It can be measured directly on certain the slower the light will travel through refractometers and hydrometers or The hydrometer is based on it, and the higher its reading will be on converted from Original Gravity. Archimedes principle that a solid the refractometer. Like hydrometers, suspended in a liquid will be buoyed up many different scales are available that Original Gravity (OG) is directly by a force equal to the weight of the convert refractive index into a unit of related to OE, with the exception that it liquid that it displaces. Therefore, the measure that is more meaningful, i.e., is a measure of specific gravity at a lower the specific gravity of the Brix, specific gravity, °Plato, etc. given reference temperature prior to substance, the lower the hydrometer fermentation. It can be measured will sink. Refractometers designed for field directly on certain refractometers and use are usually rugged and portable. An hydrometers or converted from OE. Hydrometers are usually advantage over the hydrometer is the constructed of glass or plastic. They relatively small sample size that is Apparent Extract (AE) is related to often have a cylindrical stem with a required for testing. This also saves time Final Gravity, and represents that measurement scale sealed inside and a required for cleaning and sanitizing the portion of the OE present as residual carefully weighted bulb to make it float hydrometer equipment. sugars which were not converted to upright. In use, the hydrometer is gently yeast biomass, ethanol, or CO2 during lowered into the liquid until it floats Although refractometers are also fermentation. It can be expressed freely. The reading is taken at the point dependent on temperature, certain interchangeably as °Plato, Brix, or where the surface of the liquid (the refractometers are made with automatic dissolved solids and is usually meniscus) crosses the scale on the stem temperature compensation; in fact, you determined through calculations based of the hydrometer. shouldn’t rely on results from a on OE, or specific gravity as read on a refractometer without temperature hydrometer. Although the hydrometer is affected compensation. by the density of the fluid, it may have a

Final Gravity (FG) is a measure of scale inside with any particular unit of Brewers are likely to encounter two specific gravity, at a given reference measure that is related to density. One different types of refractometers; temperature, at the conclusion of important point to note is that whatever Traditional Analog and Digital fermentation and is directly related to the unit of measure, the hydrometer Handheld. AE. Specific gravity readings can signal scale is only valid at one particular the end of fermentation when they stop temperature. Hence, they must be used Traditional Analog moving. FG can be measured directly on in conjunction with a thermometer, and a hydrometer or calculated based on OE any variation from the reference Refractometer and AE. temperature must be noted and The traditional analog refractometer compensated for. is comprised of lenses and prisms that Apparent Attenuation (AA) is a focus a shadowline on a tiny glass reticle measure of the amount of sugar Also, due to the nature of the with a scale etched on it. You point one consumed by yeast during fermentation hydrometer, a relatively large sample end at a light source and look through and the extent to which the yeast has size must be used so that the the other end. The scale inside is likely been able to successfully convert hydrometer can float freely. Since the to be Brix (a measure of sucrose), wort fermentable sugars into ethanol and hydrometer is made of glass, great care specific gravity, or both. These units, CO2. It is calculated as the drop in must be taken to keep it from breaking. likely made in China, can be found for as extract during the fermentation divided Obviously, the hydrometer is not $60.00 and are aimed at by the OE. designed to be used as a field the home hobbyist. little as $35 to instrument.

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The Traditional Analog Refractometer can be further split into 30 two categories, those with and without automatic temperature compensation. However, since refractive index (the 25 underlying method of measurement) is very temperature dependent, refractometers without temperature compensation should not be considered. 20 However, analog refractometers with temperature compensation are compensated based on sucrose, which is problematic since there is so little 15 sucrose in wort. Digital Handheld Refractometer 10 The second type of refractometer is the digital handheld refractometer. Brix % DS Beer Digital instruments read the refractive index of a fluid and use an internal scale 5 to convert refractive index into a useful unit of measure, such as Brix, Plato, or FIG. 1 specific gravity, and display that value on an LCD display. Like analog 0 refractometers, there are many different 1.3330 1.3430 1.3530 1.3630 1.3730 1.3830 brands of digital refractometers whose quality and accuracy can vary widely. solution consists of water, sugar, and ethanol and the three components The Truth about Refractometer How can I use a interfere with accurate specific gravity Correction Factors measurements. That said, the Refractometer for Beer? In Figure 1, you can see the refractometer is still a valuable tool difference in the relationship between during and after fermentation. sucrose concentrations, true wort Refractometers are most useful at dissolved solids, and refractive index. three points in the brewing process; Method #1: Take a measurement before, during, and after fermentation. on a refractometer using a Brix, Plato, or Wort is primarily a blend of maltose dissolved solids scale. Then take a and other sugars with very little Before fermentation, refractometers reading with a hydrometer. Finally, sucrose. Curiously, all refractometers should be used to measure the OE or OG enter the readings into an online used for beer measurement, with the of the wort. Use the Dissolved Solids, calculator to determine such things OG, exception of the certain scales on the Brix, °P, or specific gravity scales and AE, FG, AA, and ABV. MISCO Digital Beer Refractometers, are record the value. The most accurate reading for wort will be obtained by based on the mathematical relationship Method #2: Use a refractometer between refractive index and sucrose, using the Dissolved Solids scale since it Brix, Plato, or dissolved solids scale to is based on the type of sugars in actual and then temperature compensated for measure the wort OE before sucrose. wort. fermentation begins and record the

measurement. Any time after As a result, their readings are on During and after fermentation the fermentation has commenced you can specific gravity scales will not do you take another reading on the same scale any good. Refractometers are very good above the real sugar concentration of and then plug both readings into an wort.average There betweenfore, unless 1.02 toyou 1.05 are timesusing at measuring binary (two-part) online calculator or brewing software to mixtures such as sugar and water, so one of the aforementioned MISCO Pro- determine AE, FG, AA, and ABV. they are good for measuring wort. Brewing Scales, you should divide your However, once fermentation begins the Brix refractometer measurements by www.misco.com/beer Page | 3 REV140407-1

IMPORTANT: using brewing software or an online Allow time for the calculator. MISCO Digital Beer Refractometer scales temperature5. of the are scientifically derived from a complex refractometer, the 7. The refractometer is of poor quality. ambient temperature, Sadly, you get what you pay for. sugar model based primarily on maltose and the sample temperature to come to Another frequent problem for and other common wort sugars – It’s not equilibrium. refractometers advertised as beer

just another re-purposed sucrose-based refractometers, is that the internal scale 6. Take five Brix refractometer. measurements and for specific gravity is based on the old average their readings. rule-of-thumb that specific gravity is If the readings are equal to Brix multiplied by four. The drifting in one direction problem is this is just an estimate and then you probably have not allowed not the true relationship between Brix measurement. This is the reason there is enough time for the temperature to about 1.04 to get a more accurate and specific gravity. Very few analog a place in most brewing software and stabilize. refractometers with specific gravity online calculators for a refractometer scales use an accurate relationship correction factor. 7. Clean the refractometer and store it between Brix and specific gravity. for its next use.

Since the MISCO Dissolved Solids Yet another problem with using and Specific Gravity Scales are Problems with Beer Brix/specific gravity refractometers for scientifically derived from a complex Refractometer Readings wort is the temperature compensation sugar model based primarily on maltose for these instruments is based on and other sugars common to wort, you sucrose. However, wort is primarily receive a more accurate reading without A frequent complaint in brewing maltose. The difference between the need to use a correction factor. forums is that someone’s refractometer does not match their hydrometer. This maltose and sucrose is large enough to cause significant error in temperature How to use a Refractometer can be caused by a number of circumstances: compensation. to Measure Beer 1. The user failed to measure the MISCO Beer Refractometer temperature of the wort when taking Regardless of the type of the hydrometer reading or did not Benchmark Testing refractometer you have, they are used temperature correct the hydrometer for beer making in relatively the same reading. A leading third-party beverage manner. Here are some tips for getting laboratory benchmarked the MISCO the most accurate reading from your 2. Using an analog refractometer that is Digital Beer Refractometer against an refractometer: not temperature compensated.

3. Using a refractometer that was not Digital Density Meter (accurate to +/- 1. Follow the recommended procedure industry standard Anton Paar DMA5000 to calibrate your refractometer to calibrated before use. specific gravity). On samples distilled water. from a dozen different worts, the MISCO 0.000005 Using a refractometer that may have Beer Refractometer matched the been temperature compensated but 2. Make sure that the measuring surface 4. the reading was taken outside the is clean. +/- 0.001 or better in all tests. The on DMA5000 specific gravity readings to most analog handhelds). MISCO refractometer matched Original 3. If measuring beer, degas a small range of compensation (50 to 86 °F - sample by agitation or by pouring it 0.1% or better, in all but one sample. from cup to cup 20-30 times. This will Using a refractometer that is Extract readings on the DMA5000 to +/ also help cool a sample if it has been temperature compensated for sucrose 5. boiling. will cause an error that must be Using the beer calculator on the adjusted for since there is very little MISCO website, the MISCO beer sucrose in wort. Use a clean disposable pipette to refractometer was used to test a dozen

transfer a wort sample to the different finished beers. The average 6. Using a refractometer after 4. refractometer measuring surface and difference between the MISCO fermentation has started without discard the pipette.

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<0.001 specific gravity (9 than eight times the resolution of please visit www.misco.com/beer on interval). For alcohol content -definition the MISCO website. determination, the MISCO5% refractometer confidence detector arrays. The MISCO array has % ABV. competing 128 element low A world leader in the refractometer field, The complete study results are resolution compared w MISCO is headquartered in Cleveland, OH, availablematched theon theDMA5000 MISCO website.to 0.5 moreresolution than 3,256in pixelscompeting per inch digital (ppi) home to the company for 60+ years. MISCO refractometers. The net ithresult 400 is ppian designs, manufactures and sells a variety of refractometers, including: digital bench-top instrument that is more rugged and Why are MISCO Digital laboratory refractometers, inline process more precise. Plus, MISCO Refractometers better? control refractometers, digital handheld Refractometers are made in the USA. refractometers, and traditional handheld instruments. For more information, please call Besides the Pro-Brewing Scales, only SUMMARY (216) 831-1000, or access MISCO’s web site at MISCO refractometers utilize MISCO’s www.misco.com/beer. proven OPTICAL-ENGINE®, which is at TRADEMARKS & ACKNOWLEDGEMENTS the heart of every Digital Beer Although hydrometers have historically been used longer than Refractometer. Optical-Engine tech- MISCO, OPTICAL-ENGINE, Pro-Brewing Scales, refractometers, it has been demon- nology features high-precision sapphire and Palm Abbe are trademarks or registered optics, the next hardest substance to strated that refractometers are tools trademarks of MISCO Refractometer. diamond, which improve the speed and that no brewer can afford to be without. DMA5000 is a product of the Anton Paar Co. accuracy of temperature measurements. Refractometers are sturdier and easier Competing digital refractometers only to use than hydrometers for many of the - everyday tasks that face the brewer. definition detector array provides more For more information on MISCO use glass prisms. A 1,024 element high MISCO Digital Beer Refractometer,

Following is a listing of the standard Pro-Brewing Scales available from MISCO, custom configurations are available upon request on the Build-Your-Own section of our website:

MISCO Pro-Brewing Scales

Scale Unit of Measure Basis Range Resolution Precision (+/-) Temp. Comp. Basis

799 Brix Sucrose 0 to 30 0.1 +/- 0.1 Wort Sugars 800 Dissolved Solids (Sugars) Wort Sugars 0 to 30 0.1 +/- 0.1 Wort Sugars 801 °Plato Sucrose 0 to 30 0.1 +/- 0.1 Wort Sugars 802 Specific Gravity (D20/20 °C) Wort Sugars 1.000 to 1.127 0.001 +/- 0.001 Wort Sugars 803 Specific Gravity (D60/60 °F) Wort Sugars 1.000 to 1.128 0.001 +/- 0.001 Wort Sugars 804 Brewer's Points @ 20 °C Wort Sugars 0 to 127 0.1 +/- 0.5 Wort Sugars 805 Ethanol (by Distillation) Ethanol 0 to 30 0.1 +/-0.2 Sucrose 806 Balling Sucrose 0 to 30 0.1 +/- 0.1 Wort Sugars MISCO Propylene Glycol (PG) Scales for Wort Coolers & Chillers 006 Percent by Volume PG 0 to 100 % 0.1 +/- 0.1 PG 008 Freeze Point °F PG +32 to -60 °F 1 +/- 2 PG 009 Freeze Point °C PG 0 to -51 °C 1 +/- 1 PG

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readings is the fact that the MISCO Specific Gravity Scales dissolved solids scale is temperature Appendix I Specific gravity is the relative compensated specifically for wort, density of a fluid at a reference compared with sucrose compensation in MISCO PRO-BREWING a Brix refractometer. temperature, relative to the density of SCALES™ water at a reference temperature. Brix Scale Specific gravity is often measured with a hydrometer. In order to obtain an The Brix scale is probably the most To accommodate brewers from accurate reading from a hydrometer, the recognizable scale for most brewers in different regions of the world, who solution measured must be at the the US and Canada. It is simply the desire to measure beer with their own reference temperature of that percent weight of dissolved solids preferred units of measure, MISCO has hydrometer or the solution temperature (sucrose) in a sucrose/water solution. It created a variety of beer scales from needs to be measured and a correction is used in beer brewing because the Brix which to choose. The user may select up applied to the reading. units are a convenient unit of measure to five scales including Total Dissolved found on many refractometers and Solids (sugars), Brix, °Plato, Specific Specific gravity readings are hydrometers. Within the accuracy of Gravity, Brewer’s Points, Balling, and typically denoted in the form “D t1/t2,” most handheld refractometers, Brix is ABV. where “D” represents relative density, synonymous with °Plato. t1 is the reference temperature of the

Dissolved Solids Scale solution, and t2 is the reference However, the Brix scale is used more The Dissolved Solids Scale was temperature of water. One problem accurately in the wine industry, since created specifically for beer; it is not just faced by the brewer is that most grape must is composed primarily of a repurposed sucrose scale, nor is it brewing hydrometers are calibrated for sucrose, whereas beer is composed based strictly on maltose alone. The a reference temperature of 60/60 °F primarily of maltose with very little scale is instead scientifically derived and most reference data and sucrose. The difference between the from a complex beer model with a sugar calculations are based on a reference sucrose and malt-ose content is often profile that is specific to wort. The sugar estimated and used as the basis of a cor- profile accounts for maltose, Therefore, we offer two specific gravity rection factor in many popular beer maltotriose, dextrose (D-glucose), scales,temperature Specific ofGravity 20/20 (D 20/20 °C °C) (68°F). and calculators. Although the Brix scale is fructose, and sucrose, with the Specific Gravity (D 60/60 °F). based on the sucrose/refractive index remainder consisting of larger relation-ship it is temperature saccharides, and other material which is The 60/60 scale should most closely compensated for wort, just like the non-fermentable by standard brewer’s match your brewing hydrometer and other Pro-Brewing scales. yeast (in general, saccharides larger the 20/20 scale eliminates the need to than DP3). °Plato Scale make a correction when using the readings for calculations or comparing Degrees Plato represents a unit of The Dissolved Solids Scale to reference data. Unlike your measure dating back to Brewers from represents the true mathematical hydrometer, however, the refractometer the late 19th Century. The intention of relationship between actual wort scales are automatically temperature the scale was to convert specific gravity, dissolved solids and refractive index. compensated and only require one or as measured with a hydrometer, into the This dissolved solids content is two drops for a sample. weight percent of sucrose, as a measure expressed in grams of sugars per 100 of total fermentable material. The Plato grams of wort and is equivalent to One more note about the specific scale is historically more popular in percent weight per weight. For most gravity scales. During fer-mentation, central European brewing and is very calculation purposes the measurement yeast converts wort sugars into carbon nearly equivalent to the Brix scale which can be used in place of Brix or °Plato. dioxide and ethanol. As fermentation is used predominantly in the US. progresses, sugar content de-clines, Although the Plato scale on the MISCO Measuring wort on the percent while ethanol content increases. Since Digital Beer Refractometer is based on dissolved solids scale will give you a ethanol is less dense than water, and the sucrose/refractive index more accurate indication of true total less dense than the sugar it is replacing, relationship, it is temperature sugar content of wort, rather than trying the specific gravity decreases with time, compensated for wort instead of to estimate it using a Brix refractome- until it stops declining, signaling the end sucrose, for a more accurate reading. ter. Also contributing to more accurate of fermentation.

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sucrose). They are also temperature anymore and for all practical purposes Refractometers are ideal for compensated for wort. are the same as Brix and °Plato. measuring binary (two-part) mixtures, such as wort, which is just sugar and Brewer’s Points The Balling scale was a hydrometer water. Since the refractive index of Points are a type of shorthand used scale developed by Ger-man chemist water is a constant, the sugar becomes by brewers and are the equivalent of the variable. Therefore, the addition or ((specific gravity - 1) x 1000). For measure the concentration of a sucrose Karl Balling in 1843. It was designed to loss of water, or an increase of sugar, example, wort with a specific gravity of solution, as the percentage weight of will change the refractive index in a sucrose at it is used primarily for beer predictable way. The addition of Using the old brewer’s rule-of-thumb, it making, another element, such as ethanol, is1.045 easy would to estimate be said toBrix have of 45Plato points. by creates a problem for a refractometer. dividing points by four. For exam-ple, a Ethanol Concentration With sugar, ethanol, and water there are If you know the OE and AE, you can now two variables and it is nearly wort would have an estimated °Plato or use an online calculator or brewing impossible to determine whether the brewer would estimate that a 45 point software to calculate the alcohol content change in refractive index is caused by multiplying Brix, °Plato, or dissolved water, sugar, or ethanol. Therefore, a solidsBrix valueby four of would 11.25. give Alternatively,you a rough need to know the alcohol content to a refractometer cannot be used to estimate of points. higherto about level 0.5% of ABV.accuracy, In the you event will that need you to “directly” measure the specific gravity distill the finished beer to boil off the during or after fermentation. The MISCO Pro-Brewing Brewing ethanol, make up the volume with Points Scale is based on the relationship distilled water, and then measure the Fortunately, if you know the original between wort specific gravity and distillate with a refractometer equipped gravity (OG), Brix, °Plato, or dissolved refractive index (not sucrose). It is also with an ethanol scale. solids of the wort you can simply plug temperature compensated for wort. that value, together with the current Propylene Glycol measured value (during or after Balling Units Although there is no Propylene fermentation) into a beer calculator to Karl Balling constructed a method Glycol (PG) in finished beer, brewers obtain accurate estimates of alcohol and a series of tables relating specific often use PG in their chiller systems and content and real extract. gravity to the percent by weight of need a way to measure the freeze point sucrose in a sucrose water solution in or concentration. MISCO has a number The MISCO Pro-Brewing Specific the mid-19th century. Fritz Plato of PG scales that can be added to the Gravity Scales are based on the improved upon the relationship and MISCO Digital Beer Refractometer. relationship between wort specific published his tables in the early 20th gravity and refractive index (not century. Balling units are seldom used

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