Smart Spectrophotometers Offer a Better Way to Measure the Color of Cookie Samples
smart spectrophotometer
High-quality cookie products should be consistent in color from batch to batch. Image Source: Shutterstock user Natali Zakharova

Few people can resist nibbling on a perfectly-baked cookie. Many find the mouthwatering, nostalgic aromas of caramelized sugar coupled with the rich golden brown crumbles downright irresistible. But if you’ve ever eaten an under or overbaked cookie, you know that not all cookies are as delicious as they should be. Factors like setting the oven temperature too high or too low or baking the cookies for too long or too little time could negatively impact the texture and color of the cookie as well as someone’s experience eating it.

This is why large-scale cookie manufacturers need to carefully measure the color of their cookie products. Using a smart spectrophotometer that is capable of accurately measuring the color of textured samples (like crumbly cookies), you can ensure that every batch of cookies is baked to perfection and that they all appear uniform in color to your customers. Whether you produce just a few thousand packages of gourmet cookies every year, or you make millions of cookies in a wide variety of flavors and textures, a smart spectrophotometer can help you refine your manufacturing process.

Color is a Sign of Cookie Quality

The color of cookies and other baked foods can tell you a great deal about how the product will likely taste. This is due to caramelization and the Maillard reaction, a complex chemical process that causes food to turn brown as it’s exposed to heat.1 During the Maillard reaction, the proteins and sugars in the food are broken down by high temperatures, which results in deeper coloration and a significant change in flavor and aroma. In the case of cookies, the Maillard reaction browns the color of the raw cookie dough and produces strong aromatic compounds—that classic freshly-baked cookie scent.

For cookie manufacturers, paying close attention to caramelization and the Maillard reaction is important because too much exposure to heat over time could result in an overly bitter, brittle cookie. Likewise, too little heat exposure will impede the development of the Maillard reaction or caramelization, and the cookie will be soft, pale, and somewhat bland in flavor. Customers are aware of the connection between cookie color, texture, and quality, and the appearance of the cookie may impact a customer’s buying habits.2 This is why you need a smart spectrophotometer to ensure that all of your cookie products have gone through just the right amount of caramelization and appear consistent in color overall.

smart spectrophotometer
Significant variations in cookie color could be a sign that your industrial oven temperature is set too high or too low. Image Source: Shutterstock user Brent Hofacker

Measuring the Color of Your Cookies Can Be a Challenge

Even though the color of cookies plays a major role in the perception of cookie quality, measuring this color is a complex and sometimes frustrating process for manufacturers.3 Irregular textures, poor equipment maintenance, and needlessly time-consuming measurement protocols can make it much more difficult to analyze the color of your cookie products. Here are just a few of the challenges you might face:

Irregular Texture

The first hurdle that cookie companies face when testing their products’ color is that cookies are rarely completely uniform in shape, size, texture, and color. For example, a chocolate chip cookie usually has deep cracks that appear darker in color compared to other smoother areas of the cookie. These cookies also contain dark-colored chocolate chips that are scattered randomly throughout the baked dough. Both of these factors make it difficult to analyze the overall color of the product using the naked eye alone. Even some standard benchtop spectrophotometers struggle to accurately measure the color of a highly-textured sample like a cookie. With some instruments, you might have to change the texture of your sample entirely (by blending it into a powder, for example) before you can accurately measure the cookie’s overall color.

Time-Consuming Measurements

Not only does the texture of the cookie pose a challenge, it can also be time-consuming and labor-intensive to measure cookie samples individually. As a large-scale cookie manufacturer, you have to analyze the color of potentially thousands of cookies every year. Measuring one cookie at a time takes a great deal of time and effort. However, measuring just one cookie to represent an entire batch is risky, as any single cookie may not even be a reliable representation of batch consistency. If, for example, you choose one sample cookie that happens to be slightly darker or lighter in color compared to other cookies in the same batch, then it may cause you to waste a perfectly good batch of cookies because you believe that they’re all too dark or too light in color.

Equipment Wear and Tear

Normal wear and tear on your color measurement instruments can negatively impact the accuracy of your measurements. This is especially true when you use sample holders that have glass or plastic coverings that protect the sample inside. In many benchtop spectrophotometers, you place your sample inside of the holder and then cover your sample with the holder’s glass or plastic case, preventing the spectrophotometer’s sensor from touching the sample directly. However, over time, these glass or plastic sample coverings may become scratched or otherwise damaged, and this could prevent the spectrophotometer from making an accurate color reading. You’ll have to frequently replace your plastic or glass holders to ensure that your measurements remain accurate.

Each of the factors above can impact the accuracy of your cookie color measurements. However, when you invest in smart, non-contact spectrophotometers like HunterLab’s Aeros, you can overcome these challenges with ease.

How a Smart Spectrophotometer Solves Your Color Measurement Challenges

A smart spectrophotometer like the Aeros is specifically designed with textured products, like cookies, in mind. So, what makes the Aeros smart? The answer lies in its sophisticated use of technology that helps to overcome the challenges of analyzing textured and irregular samples:

Measure Your Textured Samples With Little Effort

The Aeros can accurately determine the distance between its sensor and the cookie sample below it, and it will self-adjust to the perfect height necessary for optimal color measurement; if you needed to measure the color of two different types of cookies, the Aeros would automatically reposition itself in response. So, a thin, flat sample of sugar cookies will likely be measured from a fairly low height, whereas a textured, lumpy batch of oatmeal cookies will likely be measured from a higher height. You won’t have to make these height calculations yourself because the Aeros’ smart sensor technology adjusts itself based on every new sample. You also won’t have to blend your cookie samples into a powder or go through any other destructive or labor-intensive sample preparation, as the Aeros is a non-contact instrument capable of measuring the color of textured cookies in their original form.

Measure More Samples At Once

The Aeros also overcomes the challenge of time-consuming individual cookie measurements by virtue of its generous sample area. In fact, the sample area measurement is the largest in the world, allowing you to put multiple samples on the sample tray simultaneously. From here, the instrument takes 35 different measurements in just five seconds while the smart sample platform rotates automatically in order to cover as many cookie samples as possible, allowing you to test a dozen cookies (perhaps more) simultaneously. You won’t waste time on individual sample tests, and you’ll also get an accurate sense of the overall color consistency of your cookie batches rather than relying on just one cookie to represent the entire batch. Additionally, you can share your data directly from the instrument to your company’s network via email or print results directly from the Aeros, saving you additional data gathering and processing time.

Simplify the Maintenance and Cleaning Process

The Aeros is specifically designed to minimize equipment wear and tear as well as sample contamination. As a non-contact spectrophotometer, the Aeros’ sensor never touches the sample or the sample holder, which means you’ll no longer have to use glass or plastic covers to protect your cookie samples and sensor. You won’t have to worry about glass or plastic coverings getting scratched or damaged over time because the Aeros doesn’t use them at all. Instead, the instrument adjusts its height automatically, making accurate measurements from a safe distance without the need of any plastic or glass protective covering. Additionally, sealed motor compartments and optics prevent cookie crumbs from wedging inside of the instrument. You can also completely remove the rotating sample holder to clean it, preventing cross-contamination between one sample batch and the next.

Using all of these features, the Aeros will help you obtain the most accurate and precise cookie color measurements possible, allowing you to refine your manufacturing process and ensure reliable color quality control with little hassle.

HunterLab Innovation

As a pioneer in the field of spectrophotometry, HunterLab has worked closely with the baked goods industry for over 60 years to help, manufacturers find the ideal instruments for their individual products. Today, our renowned spectrophotometers come packaged with state-of-the-art color quality control software, such as the Aeros’ EasyMatch Essentials, that is perfectly suited to capture, analyze, share, and store color data. Contact us to find out more about Aeros or any of our color measurement instruments and let us help you select the right tools for your needs.

  1. “An Introduction to the Maillard Reaction”,
  2. “How to Tell When Literally Every Baked Good Is Done”, November 2017,
  3. “Quality and Energy Control of Industrial Biscuit Baking”,
Smart Spectrophotometers Help the Coffee Industry Increase Accuracy of Color Measurements
coffee color measurement
A smart spectrophotometer can measure the color of hundreds of coffee beans simultaneously. Image Source: Unsplash user Jason Wong

The United States is home to some of the most avid coffee drinkers in the world. About 64 percent of adults in the U.S. say that they drink at least one cup of coffee every single day.1 While this is great news for the coffee industry, it also presents a potential challenge for coffee manufacturers. To meet this daily high demand for both quantity and quality, manufacturers have to make sure that their products are as consistent and delicious as possible. Just one bad experience with unevenly-roasted beans could impact a customer’s perception of the product in the future.

This is why color quality control is essential for the coffee industry. Color is often closely tied to the roast level and flavor of the coffee, so having a consistent batch of beans is important. But what’s the best way to ensure color consistency in your coffee products? You may consider using a smart spectrophotometer that’s specifically designed to measure the color of textured samples like whole and ground coffee beans. When you use a smart spectrophotometer, you’ll not only get the most accurate color measurements possible, you may also save yourself a significant amount of time and effort in the process.

Measuring the Color of Coffee Samples Isn’t Always Fast or Simple

Although color quality control is an essential step in the coffee manufacturing process, that doesn’t necessarily mean that measuring the color of coffee is easy or quick. In fact, there are a number of challenges that coffee manufacturers face when they try to analyze the color of their beans. Here are just a few of these potential hurdles:

  • Inaccurate Analysis: If you use the naked eye alone to analyze the color of your beans or ground coffee products, you may misinterpret your product’s color. This is because the perception of color is subjective between different people and because certain environmental factors (like lighting) can make the color appear darker or lighter than it really is.
  • Sample Sizes That Are Too Small: A small sample of coffee may not accurately reflect the color of the entire batch. For example, if some of your coffee beans were closer to the roasting heat source than others, then those beans will likely be darker in color.2 If you only measure the color of those beans, then you may end up throwing out the entire batch because you believe all of the beans were over-roasted. In general, measuring a larger sample of your coffee product will provide you with more accurate results because it will be more reflective of the entire batch.
  • Time-Consuming Measurements: Even if you use a spectrophotometer to analyze the color of your products, many standard benchtop and portable instruments are only capable of taking small area measurements of a sample. This means that you can only analyze the color of a few beans or coffee grounds at a time. To determine whether the entire batch falls within you color tolerance, you would have to take multiple measurements of many small coffee samples and average these separate measurements to get your final color consistency results. This process takes a great deal of time and effort.
  • Sample Holders Need to Be Replaced: Standard spectrophotometers also often come with sample holders that include a glass or plastic covering designed to protect the sample inside from touching the instrument’s sensor. The problem with these types of holders is that they can become scratched or contaminated with product over time, and this may impact your color measurement results. You have to replace these holders frequently in order to ensure that you’re getting accurate measurements every time.

For these and many other reasons, coffee manufacturers may find a smart spectrophotometer like HunterLab’s Aeros more beneficial for their color quality control process. The Aeros is a smart non-contact spectrophotometer that solves all of the challenges above, allowing coffee manufacturers to get accurate color readings quickly and efficiently.

coffee color measurement
The color of your coffee beans can impact the perception of quality, and even the flavor, of your final product. Image Source: Unsplash user Kurniawan Adhi

How the Aeros Solves These Challenges

The Aeros smart spectrophotometer has a number of features that make it ideal for measuring the color of coffee samples, such as:

You Won’t Have to Clean or Replace Sample Holders

To start, the instrument is a non-contact spectrophotometer, meaning that the sensor never touches the sample directly. However, the Aeros takes this feature one step further by automatically detecting where the sample is in the holder and adjusting the sensor height to an ideal position above the sample. This automatic sensor adjustment is part of what makes the Aeros “smart.” The sample will never touch the sensor yourself and you won’t have to waste time cleaning and prepping plastic or glass covers to protect the sensor. This also means that your measurements stay consistent over time since you won’t have to deal with scratched or contaminated covers.

You Can Take Much Larger Measurements

The Aeros also solves the challenge of small area measurements. Compared to standard benchtop and portable spectrophotometers, the Aeros is capable of measuring more coffee at once. In fact,  it has the largest sample area in the world. This allows you to test the color of potentially hundreds of beans simultaneously. But how does the Aeros measure such a large sample area? By rotating its sample platform. As the platform rotates around, the sensor takes 35 different measurements, covering every surface of the platform in just five seconds. It would take someone hours to perform the same number of measurements using a standard spectrophotometer operating with a Small Area View (SAV).

You’ll Get Reliable, Accurate Color Readings

Finally, the Aeros solves the challenge of inaccurate or biased color perception. After the instrument takes all of its measurements, it averages them automatically, providing you with both a color measurement number and a corresponding Specialty Coffee Association of America (SCAA) number, which tells you where the color falls on the standard roast scale. Rather than comparing your beans or grounds to SCAA tiles with your naked eye (which can give you inaccurate results), the Aeros will tell you with certainty where your product falls on the SCAA scale with the highest level of accuracy. This allows you to refine your manufacturing process and aim for the perfect roast, whether that’s a light roast or a certified gourmet-quality medium roast.3

coffee color measurement
A well-roasted batch of coffee beans will be nearly identical from bean-to-bean, with very little mottling or blotchy, uneven browning. Image Source: Unsplash user Ben Kolde

How to Use the Aeros to Measure Your Coffee Products

To use the Aeros, you simply place your coffee sample into the platform holder. You don’t have to do any prep work on your sample ahead of time—the instrument measures the coffee in its whole state. From here, you simply touch the start button, and the Aeros adjusts its sensor height and begins the measurement process. The platform rotates as the sensor takes in all of its individual measurements, and within seconds, you’ll see a display of both the color measurement number and the SCAA number on the screen. From here, you can choose to email, print or stream the data across your network. To take measurements of additional coffee samples, all you have to do is remove and empty the sample tray and quickly clean off any excess coffee. You can repeat this process for as many batches as you need.

If you have any questions about this process, the Aeros also includes real-time Remote Access Support (RAS). This innovative support service allows you to ask experts technical questions about the instrument long after your purchase. Whether you need help finding all of your instrument’s features or you need to update your software, our experts will walk you through the process from the Aeros’ integrated chat feature.

HunterLab Innovation

For more than 60 years, HunterLab has introduced innovative solutions to common industry challenges. Our line of spectrophotometers is designed to be as reliable and efficient as possible. From smart benchtop spectrophotometers to handheld instruments, we provide the tools you need to implement a dependable color quality control protocol. Contact us today to find out more about our specialized line of color measurement instruments.

  1. “Americans Are Drinking a Daily Cup of Coffee at the Highest Level in Six Years”, March 17, 2018,
  2. “Uneven Roasts”,
  3. “Roast Level for Cupping”,
Grey Change and Grey Stain Scales Help the Textile Industry Create Durable Colors
grey change color scale
The Grey Change scale can help detect the amount of fading that occurs in different textiles after they’re washed. Image Source: Max Pixel

A homeowner decided to wash a set of red living room curtains for the very first time, carefully following the cleaning instructions listed on the label. He avoided bleach products and washed the curtains on the delicate cycle setting. But despite his diligence, the color nonetheless faded significantly after washing; his once-red curtains were now a shade of faded pink, and they no longer matched the color scheme of the living room.

This is a common challenge that textile manufacturers face, whether they’re dyeing textiles for curtains, blankets, clothing or any other colorful fabric. If a large-scale textile manufacturer fails to identify problems with fading or color bleeding in its products early on, it could lead to customer dissatisfaction later. Yet there is a solution to this problem. Using the Grey Change and Grey Stain color scales, which are included in the software packaged with some advanced spectrophotometers, textile manufacturers can identify both fading and bleeding early on in the dyeing process. These two color scales are specifically designed to analyze color fastness and dye durability, allowing manufacturers to refine their dyeing processes and invest in the most durable dyes for their products.

The Problem with Some Colorful Textile Dyes

Certain textile dyes are more prone to fading and bleeding than others and environmental factors like exposure to UV rays or frequent washing can significantly alter product color depending on the chemical makeup of the dye.1 This is why textile manufacturers must consider the color fastness of the dye being used for each product, as different types of dyes will have different benefits and downsides.

The term “color fastness” refers to a dye’s durability against fading and bleeding; a dye that has excellent color fastness will be durable and long-lasting, even when exposed to environmental factors that cause color fading or bleeding. A dye with poor color fastness won’t be as durable. For instance, one type of dye that is known for its excellent color fastness is an azoic or naphthol dye.2 These dyes produce bright, bold colors, especially in the red and orange spectrum, and are highly resistant to fading in the wash or even when exposed to bleach. Conversely, acidic dyes tend to be resistant to color fading when they’re exposed to sunlight, but they’re much more prone to fading and bleeding after washing. Here are a few more examples of common textile dyes and their typical color fastness:

  • Basic: Excellent light and wash fastness.
  • Disperse: Good light and wash fastness, but sensitive to nitrogen gas.
  • Direct: Fair lightfastness, but very poor wash fastness.
  • Reactive: Great light and wash fastness, but prone to bleeding excess dye unless it’s washed well during manufacturing.
  • Mordant: Good light and wash fastness, but only available in a small range of colors.
  • Premetallized: Good light and wash fastness, but only available in a small range of colors.
  • Sulphur: Fair light and wash fastness.
  • Vat: Excellent color and wash fastness. It’s perhaps the most durable textile dye used by manufacturers.
  • Fluorescent brighteners: Fair wash fastness, but very poor lightfastness.

While this basic list of color fastness can give you a general idea of which textile dyes will be the best choice for your textile products, the list isn’t foolproof. For example, although sulphur dye is generally fairly resistant against color fading after being washed or exposed to sunlight, some manufacturers have found that certain sulphur-dyed yarns will occasionally fade after about six months of use. This is why it’s important to test your dyes for true color fastness using the Grey Change and Grey Stain scales; every dye reacts differently with each fabric you use, so by testing each new product in advance, you may produce more durable, colorful textiles.

grey change color scale
Textile dyes vary in color fastness depending on the chemical makeup of the dye or the type of fabric that a manufacturer uses. Image Source: Shutterstock user Pichit Tongma

Using Grey Change and Stain Scales to Ensure Color Fastness

Both the Grey Change and the Grey Stain color scales can help you refine which textile dyes you use to create your products as well as evaluate your dyeing processes. These color scales work by comparing a textile’s baseline color (the color of the product shortly after being dyed) to the color of the product after it has been washed or exposed to light. While it’s possible to perform a rough version of this color analysis using visual assessment alone in some cases, you may not detect a subtle change in color between washed and unwashed textiles with the naked eye. More importantly, visual assessment does not allow you to distill your observations to the objective data necessary for meaningful color comparison, communication, and correlation to process variables. A spectrophotometer can help you detect, record, analyze, and communicate even subtle color changes in color after the very first wash as well as over time, allowing you to determine whether the dye you’re using is durable enough for your products and identify areas of potential process improvement.

The Grey Change Scale Detects Early Fading

To best detect color fading, you can use the Grey Change scale, which identifies even subtle losses of color in textile samples. The Grey Change scale works by comparing the baseline color of the sample to five pairs of grey standards, each representing a different stage of color fading. First, you can measure the color of your product sample using a spectrophotometer. From here, you can then wash your sample and re-measure the color, comparing it to the original with the Grey Change scale. If the sample receives a Grey Change scale rating of 5, that means there was no color loss whatsoever. If, however, the sample receives a Grey Change scale rating of 1, almost all of the sample’s color was lost during washing. Generally, dyes with good color fastness will have a rating of about 4 or 5 on the Grey Change scale. Dyes that noticeably fade (going from red to pink, for example) will generally have a rating of about 3 on the scale. Dyes that are very prone to fading will have a rating of 1 or 2 on the scale.

For many manufacturers, it’s important to perform this test after multiple washes to simulate use over time. For example, a pair of dark blue jeans might appear to retain its color initially but fade to a much lighter blue after repeated washing. Quantifying those changes is critical to accurately assessing color fastness and implementing protocols to improve durability of color. Additionally, the scale can be used to quantify color change as the result of UV exposure, typically in an artificial aging environment.

The Grey Stain Scale Tests for Bleeding

While the Grey Change scale is used to detect color fading in a sample, the Grey Stain scale can be used to test textiles for bleeding and possible transfer staining. Even if a textile sample doesn’t fade in color, it’s possible that excess dye in the fabric will bleed onto other clothes during washing and result in staining. This happens often with direct red dyes in particular, especially if a piece of red fabric is washed alongside white fabrics.3 The Grey Stain scale can help you detect this problem shortly after you dye your fabric, allowing you to refine your dyeing process in response.

The Grey Stain scale works in much the same way as the Grey Change scale, analyzing the color of the sample against five standard color pairs. This time, however, you’ll measure the color of a piece of white test fabric, both before and after washing. After the white fabric is washed alongside your dyed fabric sample, you can use a spectrophotometer to analyze the color of the white fabric. Did it change in color? If the white fabric receives a rating of 5 on the Grey Stain scale, then it did not change in color, meaning that your colorful fabric sample didn’t bleed and stain the white fabric. If the white fabric received a rating of 1 or 2 on the scale, then significant color bleeding occurred, and you may have to refine the type or the amount of dye that you use in your textiles to prevent future bleeding.

grey change color scale
Even slight color fading can cause a significant change in color over time, especially in products that are frequently washed, like clothing. Image Source: PX Here

How to Use the Grey Change and Grey Stain Scales

In order to use the Grey Change and Grey Stain color scales to analyze the durability of your textile dyes, you’ll need to operate your spectrophotometers in reflectance mode. Next, you can configure the display of your instrument so that it shows you the color scales. From here, you can simply follow the specific instructions for mounting your fabric samples onto the port of your spectrophotometer. As long as you are operating in standard reflectance mode and your sample is either backed by a white uncalibrated tile or made completely opaque, you can obtain an accurate Grey color scale reading for each sample. A number of HunterLab instruments s are capable of measuring samples using both types of Grey scales, as they are included in our innovative EasyMatch QC software. Because this software is already included with the spectrophotometers, you won’t have to perform a visual assessment of the Grey color scales yourself; this analysis is done for you, with a great degree of accuracy.

HunterLab Experience

For more than 60 years, HunterLab has worked closely with the textile industry to find solutions to the varied challenges manufacturers face. Our spectrophotometers are designed to accurately detect the color of textile samples and include specialized software with the ability to make Grey Change and Grey Stain comparisons, offering manufacturers a fuller picture of their products. Using these tools and techniques, you can refine your textile dyeing process and create products that are as durable as they are beautiful. Contact us to find out more about our renowned instruments and which spectrophotometer may be best suited to your needs.

  1. “Why Does Ultraviolet Light Cause Colors to Fade?”,
  2. “Textile Dyes and Color Fading”,
  3. “Why Are Red Dyed Items Susceptible to Bleeding?”, May 23, 2007,
Analyzing the Color of Transformer Oil Using Spectrophotometric Instrumentation
color of transformer oil
The color and clarity of transformer oil can tell electrical engineers a great deal about the oil’s age and quality. Image Source: Shutterstock user ifong

An engineer working for a power utility company is asked to check whether the electrical transformers in the field are working properly. Rather than looking closely at the transformers’ hardware or performing a test run of the machine, the engineer first looks at the color and clarity of the transformer oil being used. Why? Because the color of the transformer oil can tell the engineer a great deal about how well the transformer is currently operating and detect even the smallest signs of trouble before the device is powered on. Oil tests are a fast, simple, and inexpensive method for detecting operational problems in a transformer; it’s similar to checking a car engine’s oil every month or so to ensure that the engine is working properly.

Many power utility companies frequently test the color and quality of the transformer oils they use because high-quality oils can protect their transformers from damage. In fact, transformer oil tests detect an estimated 70% of incipient failures in transformers.1 Using UV-Vis spectrophotometry, engineers and on-site operations managers can quickly test the color of transformer oil to ensure that it meets exacting standards. By performing these tests periodically, either on-site or under lab conditions, power utility companies and other industries that rely on transformers can ensure that all of their equipment is operating at peak efficiency.

color of transformer oil
Certain types of transformer oils precipitate sediment in the bottom of the transformer as the oil ages. This is why some utility companies have on-site oil filters to remove impurities in the oil. Image Source: Pexels user Scott Webb

Color is a Sign of Oil Age and Purity

Transformer oil (or insulating oil) is used to keep an electrical power transformer cool during normal operations. Because the voltage used in electrical transformers is so high, the resulting heat can damage the transformer’s core and winding.2 The oil serves as a protective liquid barrier for the transformer’s core, allowing electricity to pass through without overheating the core. These oils also prevent oxidation of the winding’s cellulose insulation by limiting the exposure of oxygen in the system. However, although transformer oil plays a major role in the function of an electrical transformer, the oil can also damage equipment if it’s not filtered properly or changed frequently enough.

Darkened coloration is the first sign that transformer oil needs to be changed or filtered. As the oil ages, it slowly changes from a pale yellow, transparent color to a deep brown, nearly opaque shade. Most transformer oils need to be filtered or changed at least every six months in order to prevent damage to the transformer, and testing the color of the oil is one of the easiest methods to determine exactly how old the oil is and whether it will still work effectively. Generally, oil that is yellow, orange, or even somewhat red in color is fresher and will work as intended. As oil ages, it transforms to a brown or black color and its efficacy diminishes. If engineers or on-site managers fail to detect these important color changes, the transformer may be more prone to problems like arcing, corona discharge, overheating, or decreased insulation strength.3 This is why testing for color is an essential step to maintaining a fully-operational electrical transformer.

Without careful oil color analysis, a transformer may experience one of the many problems listed above, which in turn could disrupt normal operations and lead to greater maintenance costs. It is usually much less expensive to periodically test for oil color consistency than it is to repair a transformer after it has failed due to overheating or arcing. Moreover, it takes time to repair the equipment after it has already been damaged, which may lead to delays in service. By testing your transformer oil color and standardizing your color measurement protocol, you may be able to prevent these problems before they become more costly.

color of transformer oil
The darker and more opaque transformer oil is, the more likely it is to disrupt a transformer’s normal operations. Image Source: Pixabay user Angelorosa

Analyzing the Color of Transformer Oil Using Spectrophotometry

Spectrophotometric color measurement is already recognized as a highly accurate method for testing the color and purity of transformer oil.4 According to a 2014 study conducted by the National Institute of Technology in India, UV-Vis spectrophotometers are an effective tool for analyzing the deterioration rate of transformer oils due to aging or thermal stress. Researchers who conducted the study found that spectrophotometers were able to accurately detect the color of oil that had aged naturally in the field, the color of laboratory-aged oil, and the color of fresh oil. The team of researchers confirmed that as the color of the oil changed (becoming darker), the proportion of aromatic hydrocarbons in the oil increased, meaning that the oil wouldn’t be as effective as an insulator in the field. In other words, color was directly correlated with oil efficacy, allowing for important insight into transformer function if analyzed with the precision afforded by spectrophotometric instrumentation.

Because transformer oil is distilled from crude oil, you can use the Saybolt or ASTM color scales to accurately detect the color of the oil and determine whether it falls within a safe tolerance. Spectrophotometers are capable of quantifying variations in color and can match them to the numbers on both of these color scales, giving you a clear idea of the oil’s age and quality. However, the type of spectrophotometer you choose will depend on your industry’s needs. For example, spectrophotometers in transmittance mode can measure the color of transparent and translucent oils, but this may not be the most effective tool when you’re working with transformer oil, as it ranges from transparent to opaque, depending on the oil’s age. A spectrophotometer that can work in both transmittance and reflectance mode is a better choice measuring the color of transformer oils, as the instruments can measure the oil at every stage of its lifecycle, from the clear, pale yellow of fresh oil to the dark, opaque brown of aged oil.

With advances in spectrophotometric technology, accurate color measurement of transformer oils and other crude oil products is a simple, streamlined process that easily be performed by operators. Using these tools, you can consistently analyze the color of your oils to keep your transformers working at peak efficiency, potentially extending the life of the transformers, preventing costly repairs, and avoiding inconvenient downtime.

HunterLab Reliability

For more than 60 years, HunterLab has worked closely with oil and chemical industries to refine their color measurement protocols and detect color change with extraordinary precision. Using state-of-the-art technology, including advanced color measurement software that can compare data to well-established industry color scale standards, our spectrophotometers represent the highest level of color analysis available. Contact us today to find out more about our renowned instruments and let us help you select the right tools for your needs.

  1. “Insulating Oil Decaying Assessment”, October 20, 2013,
  2. “Transformer Insulating Oil and Types of Transformer Oil”,
  3. “Transformer Oil Dehydration and Process”, April 16, 2016,
  4. “Condition Assessment of Transformer Oil Using UV-Visible Spectroscopy”,
When Is Sample Averaging Appropriate in Color Measurement?
sample averaging
Carpet samples can be challenging to measure because the texture may make the product appear lighter or darker than it really is. Averaging your sample measurements can help you overcome this challenge. Image Source: Shutterstock user Alena Ozerova

Some textiles are more difficult to test for color consistency than others. A textile manufacturer can easily test a swatch of solid blue jersey fabric because the material is flat, opaque, and homogenous. For these types of smooth, solid textiles, all the manufacturer has to do is take one reading on a spectrophotometer to determine whether the dyed jersey fabric meets the manufacturer’s color standards. But not all textiles are homogenous in color; fabrics like corduroy, heavy knits, and terry cloth have texture variations that making them much more difficult to measure with a spectrophotometer. If the manufacturer measures the color of such fabrics in just one small area of the sample, there’s no guarantee that this measurement will match other measurements taken of the same fabric—move just one inch to the right of your first measurement and you’ll likely find that the color reading is completely different.

When testing for color consistency, how do manufacturers compensate for textured or non-homogenous products like this? One method is to average the color measurements in order to get an overall sense of the product’s color. By averaging your sample measurements, you’ll ensure that your color readings are as accurate as possible, even when working with materials that vary significantly in texture. However, in order to use this method properly, you’ll need to know when it’s appropriate to average your samples and when you should take only a single reading. After all, taking multiple measurements of the same sample can be a time-consuming process, so it’s important to only average measurements for the products that actually require this added level of attention.

sample averaging
Averaging your measurements can help you get an accurate color reading on products like toothpaste, especially those that contain flecks of colorful suspended particles. Image Source: Shutterstock user kikovic

What is Sample Averaging?

Sample averaging is an optional color measurement method that allows you to take numerous readings of the same sample or batch in order to obtain a result that best represents the product as a whole. When you take multiple measurements of, say, toothpaste that contains colorful microbeads, each new measurement will likely be slightly different from the last. A nearly-clear toothpaste may appear mostly translucent, but if one area of your sample contains slightly more blue exfoliating particles than another area of the sample, the spectrophotometer could provide you with a color reading that isn’t representative of the entire batch of product.1 As a result, the spectrophotometer may flag the sample because it appears too blue in just one small area. By taking multiple measurements of the same sample of toothpaste and averaging the results, you can get a more accurate sense of whether the product actually falls within color tolerance.  

There are two ways that you can average color samples of your products: optical or statistical. Here are the key differences between each method:

Optical Measurements

An optical average measurement is performed by a spectrophotometer automatically. Using a color sensor, the instrument observes all of the available spatial data from the sample area of view and averages this finding in order to provide you with a single overall reading. The larger your area of view is, the more accurate this reading will be, as the instrument will have more data available to work with. However, an optical reading alone isn’t always appropriate for every sample. If you have textured samples or samples that vary in color from one area to another, then just one reading may not tell you everything that you need to know about the overall color of the product. Instead, you’ll need to take the additional step of a statistical average measurement.

Statistical Measurements

A statistical measurement goes beyond what many spectrophotometers perform automatically. When you take a statistical average of your sample, you make multiple optical measurements in succession, then calculate a total average measurement for all of those results. Manufacturers have a choice between two different types of statistical measurement methods:

  • Multiple Readings of One Sample: The first option is to take multiple readings of the same sample in different areas. For instance, if you’re measuring shag carpeting, you may set your sample in the spectrophotometer’s area of view so that only the lower right corner of the carpet swatch is visible. Then, once you get your first reading, you can rotate the swatch 90° and measure a different portion of the sample. Repeat this step as many times as you would like, until you feel as though the measurements you’ve taken fairly represent the entire sample. Once this is done, you can calculate the average of all of these measurements, which should give you an accurate representation of the entire sample. To facilitate this process, some spectrophotometers come equipped with sophisticated color measurement software like EasyMatch QC, which will average all of your separate measurements for you.
  • Multiple Readings of Multiple Samples: The second option for taking statistical averages of your samples is to take multiple measurements from the same batch or lot of products. This may be useful if you manufacture products that are themselves mostly homogenous, but that may vary in color between each other. A good example of this is in baked goods.2 A loaf of bread may be a solid, even shade of brown, but that loaf may appear darker in color than others baked in the same batch.

To test whether your products fall within color tolerance, you can take multiple readings of different product samples, then average those readings to get an overall idea of how that batch compares to other batches. If you’re a bread manufacturer, you may find that one large batch of bread appears consistent in color from loaf to loaf, but if you compare the average readings of the entire batch to that of yesterday’s batch, you may find that yesterday’s batch was much lighter in color, on average. It could be a sign that your ovens are too hot, or that there is another issue in your manufacturing line. By averaging color for the entire lot, you can identify problems like this quickly, before they impact future products.

sample averaging
Fabrics like corduroy are textured, meaning that some areas of the sample may appear darker to the naked eye than others. Image Source: Shutterstock user Sezamnet

When You Should Average Your Samples

A wide range of industries average their color measurements in order to ensure that every product falls within color tolerance. Some of the most common examples of products that benefit from averaging include:

  • Translucent liquids that contain suspended particles (like toothpaste or gel exfoliators)
  • Thick, clear gels that contain air bubbles (like hand sanitizer)
  • Products that have scratches or grooves on the surface (like laminate flooring)
  • Hazy samples (like frosted glass)
  • Samples that vary in color or texture from one area to another (like yarn)

To average measurements for products like this, it’s usually wise to set your spectrophotometer to the largest area of view possible in order to get a more accurate reading. In addition, you may wish to rotate or refill your samples at least two to four times so that the spectrophotometer has a large number of measurements that it can average.

Although averaging your samples can offer you a more accurate reading of your products, this method isn’t necessarily the right choice for every industry or manufacturer. One potential downside of averaging is that it can take additional time to perform and in many cases, the spectrophotometer’s first measurement of the sample will closely match the findings of a statistical average measurement. For instance, if you want to measure a sample of paint, which is opaque and typically smooth in texture, then a single color measurement may be perfectly adequate for your needs. However, some manufacturers still choose to take multiple readings of paint products as an extra precaution.3 This is because environmental factors, such as sample preparation, may impact the color measurement results.

In general, you may wish to average your sample measurements if you want to obtain the most accurate color reading possible for your samples, or if your samples vary too much in texture or color to get an accurate reading from one measurement alone. Some of today’s advanced spectrophotometers are capable of taking multiple measurements of a sample automatically, and many will handle all of the essential calculations for you. It’s never been easier to average your measurements, and this method may just be the best option for your purposes.

HunterLab Flexibility

For more than 60 years, HunterLab has worked closely with manufacturers in a wide range of industries that rely on accurate color measurements to produce the best products possible. Our instruments are currently being used in industries ranging from textiles to cosmetics and from solid samples to liquids to powders. Our flexibility of service, coupled with state-of-the-art spectrophotometers and software, makes HunterLab a leader in the field of color measurement. Contact us to find out how you can get started with our advanced color measurement tools and services.

  1. “Microbeads”,
  2. “How to Measure the Quality of Baked Goods”, July 16, 2015,
  3. “How Does Paint Color Matching Work?”, December 16, 2015,
How to Avoid Metamerism in Color-Coordinated Household Appliances
metamerism household appliances
Interior designers typically match the color of kitchen appliances in order to make a kitchen appear more cohesive. Image Source: Pixnio

A few years ago, an appliance manufacturer sent out a shipment of color-coordinated washers and dryers to a major retailer. But when the shipment of products arrived, the retailer noticed a serious problem: the appliance pairs didn’t appear to be the same color at all. This complaint puzzled the manufacturer; they had visually assessed their products carefully during manufacturing and found that each pair of appliances was perfectly color-coordinated. So why did the retailer see a clear difference in color between the washers and the dryers?

It turns out that neither the manufacturer nor the retailer was entirely wrong in their visual color assessments. The manufacturer was assessing the color of the washers and dryers under incandescent lighting, while the retailer was looking at the products under the store’s fluorescent lighting. In incandescent lighting conditions, the products appeared perfectly matched, but under fluorescent lighting, they appeared to be two completely different colors. This phenomenon is called metamerism, and it’s a common challenge for appliance manufacturers.

Metamerism occurs when two different colors appear to be the same under certain lighting conditions and not the same in others. When you’re trying to color-coordinate household appliances, metamerism can be frustrating and potentially costly; if you fail to identify the phenomenon during manufacturing, you may end up shipping mismatched products to your customers or having to repaint or recoat all of your products.

Thankfully, there is a simple solution to this problem. By using a spectrophotometer that is capable of measuring color reliably and accurately, you can easily detect metamerism before products reach customers and even before products enter mass manufacturing. Spectrophotometers use advanced spectral analysis to calculate  the exact color of a product under different lighting conditions, offering you a truly accurate measurement for every color-coordinated appliance in your line.

metamerism household appliances
Under certain lighting conditions, a washer and dryer might appear to be the same color, even if they are actually different. Image Source: Flickr user Christian Brothers

The Importance of Color Coordination in Appliances

Most homeowners and interior designers prefer matching appliance sets because color coordination can make a room appear more cohesive and aesthetically pleasing. Jayme Neumann, an interior designer and promotions manager for Whirlpool, says that a room containing a matching set of appliances is almost always more visually appealing than ones that contain mismatched appliances.1 She explains, “It might look funny to just have one appliance be stainless—it may look like it’s an old [appliance], or [the homeowners are] replacing their appliances just one piece at a time.” While overtly mismatched appliances can be an issue, even a very slight color mismatch between appliances can disrupt the visual cohesion of the room; an ivory-colored oven will likely clash when placed next to a microwave that is a slightly brighter shade of white. This is why many customers often buy appliance packages, expecting perfect color matches.

Because today’s customers expect their kitchen and other household appliances to match perfectly, manufacturers must test their products thoroughly to ensure that each set truly matches. A slight variation in color between two appliances could be visually distracting, and this problem will be even more evident if the two appliances are installed right next to one another (like a washer and dryer set or a double oven).

The rise in popularity of brightly-colored household appliances also adds new impetus to think carefully about color coordination and metamerism. Decades ago, the most popular appliances were typically white, black, or stainless steel. Today, many homeowners and interior designers are choosing colorful appliances in unique shades like cherry red, dusty pink, fluorescent orange or mint green.2 In fact, one manufacturer offers more than 750 different finish options for their line of kitchen gadgets. However, these new color choices pose an interesting challenge for appliance manufacturers. Metamerism can cause these colors to appear dramatically different depending on whether they’re viewed under natural light, incandescent light or fluorescent light. And, some colors are more prone to the metamerism phenomenon than others, which can be a challenge for manufacturers that make appliances in a wide range of different colors.

How Lighting Impacts Appliance Colors

Certain colors will be impacted by metamerism to a greater extent than others, depending on the lighting conditions.3 For example, appliances that are in muted shades like taupe, grey, light blue, tan or lilac are more likely to be impacted by the metamerism phenomenon compared to brighter, more saturated appliance colors like fluorescent orange or green. This is because it may be difficult to spot a color mismatch in muted shades using visual assessment alone. In certain lighting conditions (like incandescent), these subtle colors might appear to match, but in brighter lighting conditions (like fluorescent), the subtle differences in color could become more obvious to the naked eye. Halogen lighting and natural daylight are the only lighting conditions that provide the most accurate view of the appliance’s color.4

However, you can’t guarantee that your appliances will always be viewed under halogen or natural lighting conditions. Retailers usually use fluorescent lighting in stores, and some homeowners prefer to use incandescent lighting in their kitchens and laundry rooms. But while you can’t control the lighting conditions outside of your manufacturing warehouse, you can ensure that your appliance sets match perfectly with each other in any environment. By taking metamerism into account and thoroughly testing your appliances for color variation under different lighting conditions, you can guarantee that all of your products are perfectly coordinated.

metamerism household appliances
Slight variations in color between household appliances can draw attention to them and distract from a room’s aesthetic appeal. Image Source: pxhere

How to Avoid Metamerism

Because there is a high demand for color-coordinated household appliances, manufacturers need to have reliable protocols for detecting metamerism in order to ensure that their appliance packages are a perfect color match. Using spectrophotometers, you can prevent metamerism from interfering with your color quality control process; spectrophotometers are far more reliable than the naked eye when it comes to detecting color variations and these instruments can even account for changes in lighting.

Spectrophotometers work by gathering reflectance data from your sample and can then create a spectral curve based on these findings. Samples that have identical curves will be a perfect color match, no matter what lighting conditions they’re exposed to later. Samples that have different curves, however, will not be a perfect match. When two sample curves are different but overlap at at least three points, then they are likely to be metameric. This means that the two samples may appear to be the exact same color under, say, incandescent lighting, but when viewed under fluorescent lighting, they could differ in color significantly.

In addition to identifying metamerism, a spectrophotometer can also help you closely analyze how well two different-colored samples will match under different lighting conditions.. HunterLabs EasyMatchQC software can convert a measurement of your color into 24 different illuminant/observer combinations. By comparing any pair of these combinations, the spectrophotometer will place your product sample on a Metamerism Index (MI),. On this scale, if the MI is 0.5 or less, than your samples are a good color match regardless of lighting conditions, but if the MI is between 0.5 and 1, then the sample colors aren’t as well-matched. Any samples with an MI of more than 1 are obvious color mismatches. By using this index and the spectrophotometer’s precise measurements, you can ensure that every household appliance set matches perfectly, whether they’re sitting on a well-lit showroom floor or installed in a dimly-lit kitchen.

HunterLab Reliability

For more than 60 years, HunterLab has helped manufacturers refine their color quality control methods, ensuring that all of their products are as consistent in color as possible. Our state-of-the-art spectrophotometers are capable of measuring a wide range of samples, including coating and paint finishes for high-quality kitchen and other household appliances. Contact us to find out how you can improve your own color measurement methods. Our experienced staff can walk you through each step of the process, and offer you the best tools for your needs.

  1. “Do All Appliances Have to Match?”,
  2. “Colored Kitchen Appliances”,
  3. “Color Metamerism: When Colors Are Not What They Seem”, July 24, 2015,
  4. “How to Pick a Paint Color: The Lighting Perspective”,
How to Accurately Analyze Carpet Color Using the UltraScan VIS Spectrophotometer
carpet color
The Ultra-Scan VIS can accurately measure carpet color because it takes texture into account. Image source: Pixabay user Frantisek_Krejci

A hotel chain has hired an interior designer to replace the old carpet design in every guestroom with something that looks more sleek and modern. After sifting through a number of swatches, the designer finds the perfect shade: a simple charcoal grey design that will contrast beautifully against the crisp white comforters and bed sheets that the hotel uses. But in order for the interior designer’s vision to truly come to life, the carpet color needs to be consistent from room to room. Not only does every guest room have to match, the hotel also needs to ensure that the carpeting looks seamless from the entrance of the room to every corner. If the hotel receives rolls of carpeting that vary in color even slightly, it will make every seam more obvious–the hotel will end up with a room that looks more like a patchwork quilt than a chic, modern space (commonly referred to as a “carpet sidematch problem”).1

This is just one of many reasons carpet manufacturers should take accurate color measurements of their products before releasing them on the market. However, it isn’t always easy to measure carpet color, even when you use color measurement tools like spectrophotometers. Because carpeting is soft, uneven and not always entirely opaque, analyzing the color of your samples can be frustratingly complicated. An instrument such as the UltraScan VIS, however, simplifies this process by allowing for optimal measurement methodology and the highest degree of color measurement precision. Unlike many other spectrophotometers on the market, the UltraScan VIS instrument is specifically designed to measure carpeting (among many other sample types), and makes the color quality control process fast, simple and extremely accurate.  

The Challenges of Analyzing Carpet Color

Carpet swatches seem easy to analyze at first glance, especially when designs feature just one solid color. However, carpeting is never truly “solid” in color, even if it appears so to the naked eye. If you look carefully at any carpet swatch, you’ll see that the tiny particles that make up the sample frequently vary in opacity, shape, and color. These three factors pose a number of challenges for manufacturers.   

Challenge #1: Opacity

Opacity is one of the first challenges you’ll come across when you try to measure the color of your sample using a spectrophotometer. Many carpet products are slightly translucent, and this becomes more obvious when you change the backing of your sample. For instance, your slightly translucent carpet sample will look lighter when backed by a light-colored background, but that same sample will appear much darker when backed by a dark-colored background. In order to get an accurate measurement, you have to standardize your sample backing.

Challenge #2: Shape

Carpeting isn’t flat. Rather, the material is flexible, and the tiny threads that make up the sample can shift with even the slightest pressure. The non-homogenous nature of carpeting makes it difficult to measure color unless you use tools specifically designed to handle textured samples. When a color measurement instrument presses into a carpet swatch, it creates a pillowing effectThe tiny carpet particles bend around the instrument’s measurement port, and this in turn can cast shadows that alter the overall color reading. To fix this, you need to take several readings in succession, then average those readings to get an accurate measurement.

Challenge #3: Color

Finally, the color of your sample or the type of dye that you use can cause a few unexpected problems for color measurement instruments. The most common problem that you may come across is the use of fluorescent dye in carpeting. This dye makes the product appear brighter and whiter than it is, and it is frequently used in white carpeting.2 Although this dye makes your products look whiter and potentially more appealing, it also makes your samples more sensitive to UV light. When your sample is exposed to the UV that naturally occurs in your light source, it can alter the overall measurement result, making your product appear lighter. This is why you need to cancel out the impact of UV on your sample or take UV into account when you measure your product’s color.

carpet color
Pile heights and texture can significantly affect the appearance of your carpet samples. Image Source: Unsplash user Dane Deaner

How the UltraScan VIS Overcomes These Challenges

The UltraScan VIS takes all three of these challenges into consideration. First, to overcome variations in opacity, the instrument helps you standardize the environmental conditions of your lab or test space. It comes equipped with a port insert and light trap that can be newly standardized for each sample that you measure, ensuring that every sample is backed properly and that the environment isn’t making the sample appear lighter or darker than it really is.

The instrument also operates in multiple modes; the reflectance-specular excluded mode (RSEX) works well for semi-transparent and opaque samples alike while allowing you to take texture into account. For instance, if you were measuring a high-pile carpet, then the color will likely appear slightly different compared to a low-pile carpet of the same color.3 By measuring the difference in appearance between these two samples, you can get a more accurate read on every product you manufacture.

The UltraScan VIS also overcomes variations in shape and carpet texture by offering multiple measurement options. You can clamp your sample into place and take your first color reading. Then, the instrument allows you to rotate the sample 90° and move it to a different area of the swatch. You can repeat this process as many times as you would like. Once you have several different measurements, you can average these readings, which, in turn, reduces the problem of measurement variation in non-homogenous samples. You’re not just relying on a single reading of your sample, but on multiple readings that will give you the whole picture.

And finally, the UltraScan VIS allows for accurate measurement of fluorescent or optically samples. The instrument is capable of compensating for the effects of UV lighting on a sample using UV control. The instrument can simulate D65 illumination using  a UV control filter by calibrating using an optional fluorescent standard. By fully inserting the filter, you can completely eliminate UV energy from the measurement, or, alternatively, you can measure the impact that UV has on the sample by measuring the carpet swatch both with and without this UV filter fully inserted.

carpet color
To accurately measure carpet color, you may need to take multiple measurements and average your findings. Image Source: Unsplash user Stef Versoza

Using the UltraScan VIS

To use the UltraScan VIS to measure your carpet samples, start by configuring the instrument’s software to your desired color scale, illuminant and observer. For instance, if you’re measuring an optically-brightened swatch of white carpet, then you can calibrate your instrument for the D65 illuminant using the fluorescent standard. Once the UltraScan VIS is properly calibrated and standardized, you can begin the measurement process. Cut out a small sample of carpet from a roll, ensuring that your sample is large enough to cover the entire port insert on the instrument. Hold your sample in place using a sample clamp or a compression clamp –the compression clamp is most often used for carpet samples. After your sample is firmly in place, you can take your first color reading. Then, you may choose to rotate your sample, measure in a new area, and repeat this process as needed, or you can stick with a single measurement. If you make multiple measurements, take an average of these different measurements to get one single color result. These readings can be stored for recall at a later date to compare with new batches of the same color carpet, ensuring color accuracy and consistency throughout production.

HunterLab Dependability

With more than 60 years of experience in the color measurement industry, you can rely on HunterLab products to provide you with the most accurate measurements possible. Although our instruments all have unique features, they include the same dependable and accurate design at their core. We focus on cutting-edge software, hardware, and the latest advances in technology to ensure that all of our instruments meet the highest standards. Contact us learn more about the UltraScan VIS or any other spectrophotometer in our renowned product line.

  1. “Carpet Sidematch Problems”,
  2. “How Do Optical Brighteners Affect Carpet?”,
  3. “Carpet Shading, Footprints, Pooling”,
Using the Gardner Scale to Enhance Quality and Create Color Consistency in Edible Oils
edible oils
The Gardner color scale is frequently used to measure color consistency in naturally yellow products, such as olive oil. Image Source: Unplash user Joanna Kosinska

To a gourmet chef, a fine bottle of high-quality extra virgin olive oil is a thing of beauty. Many of these high-end oils are deep gold in color, with an appearance that’s rich, thick and almost honey-like. But this isn’t the only color that olive oil can be; some oils are the color of pale straw, while others are so dark brown that they appear nearly purple.1 The color of olive oil differs significantly depending on the type of olives the manufacturer uses, how the product is handled during manufacturing, and how the final product is stored before it reaches customers. In the case of olive oil, extra virgin varieties are almost always much darker in appearance compared to more heavily-processed oils, like pure, refined, or pomace products.

Because the color of the oil can tell customers a great deal about how it was processed and stored, color consistency in edible oil products is an essential part of your manufacturing procedure. However, you can’t always use the same color classification for oil as you would for clear, transparent liquids like water or certain polymers. Oils used in cooking products are often naturally yellow to brown in color, and as such, they may require you to use the Gardner scale in order to accurately analyze and classify your product’s color consistency. Unlike the APHA/Pt-Co/Hazen color scale (which measures the purity of colorless or nearly-colorless liquids), the Gardner scale is designed specifically to measure color consistency in yellow or brown transparent samples. There is some overlap between the APHA and Gardner scales at the lowest end of the Gardner scale (below Gardner 2). However, if your sample is darker than Gardner 2, then the Gardner scale may be the best classification method for your edible oil products. Using this scale, you can attain a more accurate understanding of your edible oil products while ensuring that every batch of product is consistent and aesthetically-appealing.

edible oils
The Gardner scale can be used to give you greater insight into your edible oil products. Image Source: Pexels user Pixabay

What is the Gardner Color Scale?

The Gardner color scale is a well-established method for identifying and categorizing the color of transparent liquid products that fall naturally in the yellow to brown color range, such as cooking oils, resins, fatty acids, and wood varnishes. When the Gardner scale was originally developed in the 1920s, it consisted of 18 different liquid color standards against which manufacturers could compare their own products. Each color standard was contained inside of clear glass tubes, and the 18 different liquid colors were made from a mix of potassium chloroplatinate, potassium dichromate, ferric chloride and cobaltous chloride.2 Each tube represented a slightly different color, ranging from pale yellow (Gardner 1) to very dark brown (Gardner 18).

However, the earliest forms of the Gardner scale were imprecise and vulnerable to human error. To use the scale, you had to perform a visual comparison of the product sample against its matching Gardner liquid. Because the human eye can be biased when it comes to accurately detecting colors, these versions of the Gardner scale were not completely reliable. Moreover, the liquid inside of the glass vials was prone to natural changes in color over time, and manufacturers of Gardner scale vials couldn’t always replicate the liquid colors perfectly.  

Today, the Gardner scale has been integrated into more advanced color measurement instruments, solving many of these past inconsistencies and challenges. To use the scale, you no longer have to rely on the subjective human eye to test for color consistency between products. Rather, the Gardner scale has been converted into precise digital color data that can be included in a spectrophotometer’s software. Using spectral analysis and a 10 mm or 20mm path length transmission cell, modern spectrophotometers can triangulate chromaticity coordinates for a given sample, then compare the data to the corresponding color on the Gardner scale. If the sample falls outside of the desired scale placement, the instrument will alert the operator to the problem right away. This can help you identify inconsistencies in your manufacturing process or in the raw oil material you use to create your products. In short, the Gardner color scale can work alongside the most advanced spectrophotometers to detect even the slightest color variation for yellow or brown edible oil products.

edible oils
The Gardner color scale allows you to compare multiple transparent and translucent edible oil samples to ensure that your products are consistent in color from batch to batch. Image Source: Unsplash user Matthijs Smit

The Gardner Scale Helps Edible Oil Manufacturers Create Consistent Products

Using a spectrophotometer with Gardner scale capabilities provides a number of benefits that can help you create higher-quality, more consistent edible oil products:

Raw Material Selection

During the selection process for your raw materials, the Gardner color scale may help you identify materials that are most likely to produce the final color you desire. For example, if you want to manufacture extra virgin olive oil that is as dark yellow as possible without adding artificial coloring to your final product, then you may choose to test the raw oil produced by a number of different olive species first. This testing process will help you identify the olive variety that consistently produces your ideal oil color on the Gardner scale.

Refined Manufacturing

Another use for the Gardner scale among edible oil manufacturers is to ensure color consistency from batch to batch. Various steps in the manufacturing process can impact the final color of the oil product, which may impact both the real and perceived quality of the oil. When making olive oil, for example, manufacturers press the olives in order to extract liquid fat from the fruit. If the olives are exposed to too much oxygen during this process, the oil may oxidize and change color, resulting in a lower-quality product.3 Similarly, the process of bleaching or refining the oil may cause it to appear lighter in color compared to an oil that has not been through this process. By testing your edible oil for color consistency throughout the manufacturing process, you can ensure that your products are being processed exactly as intended, as discoloration could be a sign of an inconsistency in the pressing or bleaching process.

Safer Storage

Finally, the Gardner color scale can help you identify improper storage conditions. Edible oil products are highly sensitive to changes in temperature, lighting, and air quality. For instance, food-grade oil that has been stored in temperatures above 65 degrees is prone to heat damage, which may cause it to lighten significantly in color.4 Likewise, oils exposed to too much oxygen as a result of an improper container seal and oils that are exposed to bright lights or natural sunlight are also likely to undergo undesirable color changes before they reach your customers. Using a spectrophotometer that is capable of measuring edible oil against the Gardner color scale, you can ensure that your products are being stored properly before they are shipped to your customers or distributors. Additionally testing a sample of your oil while it’s in storage may help you identify storage problems before they negatively impact your future products.

How to Use the Gardner Scale

If your edible oil products fall somewhere within the pale yellow to dark brown range of the color spectrum, then the Gardner scale can help you identify the precise color of your sample with a high degree of accuracy. To ensure that your spectrophotometer is accurately measuring your edible oil samples against the Gardner scale, you may choose to standardize the instrument against a physical liquid Gardner color standard. This performance qualification step is optional, but it may help you monitor the accuracy of your measurements over time. Once you’ve standardized your spectrophotometer and ensured that it is accurately measuring your samples against the Gardner scale, you can then use this scale in the future to detect the color consistency of all of relevant samples.

Generally, the Gardner scale is an accurate comparison tool when measuring the color of yellow or brown translucent liquids. If, however, your products are mostly colorless,  the APHA color scale may be a better color measurement tool. For example, if you manufacture refined soybean oil, you may find that the APHA color scale is perfectly adequate for your needs. This is because refined soybean oil is virtually clear, with only a very slight, pale yellow tint.5 Since this oil product is nearly colorless, the APHA scale can help you identify color variations or imperfections in your sample; you don’t necessarily need the Gardner scale for this process.

However, you don’t necessarily have to commit to one scale or the other right off the bat. EasyMatch QC software, which is included with HunterLab’s spectrophotometers, is capable of capturing APHA and Gardner color scale data simultaneously, giving you a higher degree of flexibility. This is particularly useful in the case of edible oils, as some manufacturers initially use the Gardner scale to analyze raw oil, which may still contain a great deal of yellow pigment. The APHA scale may then be used as the oil becomes clearer and less yellow via refinement or bleaching. HunterLab’s innovative technologies make it easier than ever to analyze your edible oil samples in the best way possible for your purposes.

HunterLab Technology

For more than 60 years, HunterLab has been a pioneer in the field of color measurement. In that time, we have worked closely with a wide range of industries—including those in the food and chemical sectors—to create the tools necessary to ensure color consistency in every product. Today, we offer a comprehensive line-up of portable, benchtop, and on-line spectrophotometers designed with the diverse needs of our customers in mind, giving you the highest level of insight into your products and processes. Contact us to learn more about our renowned instruments, customizable software packages, and world-class customer support services and let us help you select the right tools for your needs.

  1. “Five Reasons Why Olive Oil Comes in Different Colors”, July 31, 2014,
  2. “Gardner Color”,
  3. “Ultimate Guide to Olive Oil”,
  4. “How Storage Conditions Can Make or Break the Quality of Your Bulk Olive Oil”, May 13, 2014,
  5. “Soybean Oil Nutrition Facts”,
Analyzing the Color of Scarce and Expensive Pharmaceutical Materials via Small Sample Testing
small sample testing
Many pharmaceutical companies choose to test small sample sizes when the cost of the product is especially high. Image Source: Shutterstock user Iryna Imago

In an ideal world, drug manufacturers could test large batches of any material for color consistency and quality. However, this isn’t a reality for many pharmaceutical companies. Often, the active ingredients that go into a life-saving cancer treatment or a promising new Alzheimer’s medication are expensive to develop, difficult to synthesize, or made from rare, finite natural resources. This means that drug manufacturers have to carefully measure out their test samples, and in some cases, the material is so expensive that they need to be particularly frugal with their sample sizes. For instance, Soliris, a drug used to treat a very rare genetic condition called atypical hemolytic-uremic syndrome, is one of the most expensive medications in the United States—it sells for $18,000 per dose.1 In order to perform quality control tests on an expensive medication like this, manufacturers typically opt for the smallest sample sizes possible to avoid wasting product.

But when your sample size decreases, it can make the color measurement process much more complicated, as many color measurement instruments are incapable of accurately analyzing the color of very small samples; the equipment is typically designed with larger sample sizes in mind, and these one-size-fits-all tools lack the accessories required to measure micro samples. However, there are a number of high-quality spectrophotometric instruments and accessories on the market that are designed specifically to measure small samples with the highest degree of accuracy. When you use one of these instruments in your lab, you can significantly shrink your sample size requirements, helping you preserve valuable materials.

Why Color Consistency Matters

Measuring the color of your pharmaceutical products is important for two primary reasons. First, the color of a drug can help you determine whether there are impurities or contaminants in your sample; if a liquid cough suppressant is supposed to be completely clear, yet your spectrophotometer detects a yellow tint, then it’s possible that your sample was contaminated, or that there is something wrong within your manufacturing line. The second reason color measurement is important is customer perception. Generally, customers are more likely to trust medications that are consistent in color from pill to pill or batch to batch. Additionally, studies have shown that the color of a medication can impact users’ perception of sensory experience and efficacy. The color of medication can even affect whether users adhere to their prescribed medication plans, making color critical to ensuring therapeutic benefit.2 However, when you’re working with scarce or costly medications, the color quality control process can also grow expensive or even compromise medication supply. You have to waste a certain amount of product in order to test for color consistency, and the more expensive your product is, the greater impact your test sample size has on your bottom line and the availability of usable medication.

small sample testing
Testing small liquid samples requires the use of specialized color measurement accessories. Image Source: Shutterstock user Davizro Photography

High Manufacturing Costs Require Smaller Test Samples

There are a number of reasons medications are expensive to produce. Some of the most notoriously expensive pharmaceutical products, for example, are biologics. This category of medicine includes vaccines, antibodies, and recombinant proteins (made when a lab joins genetic material from different sources). It’s the fastest-growing category of products in the pharmaceutical industry; in 2008, biologics made up almost 30 percent of the 100 top-selling drugs in the world and that number is increasing. Biologics are manufactured using a biological process, not a chemical process. Because these products are made from raw materials that are rare and difficult to produce, the price of these products is typically much higher than it is for drugs made using synthetic chemical processes; just one dose can cost as much as $10,000.3

If you manufacture your products using any rare raw materials, the scarcity and extra cost associated with these ingredients may force you to use smaller sample sizes when testing for color consistency. For instance, some chemotherapy drugs contain platinum, which is among the most expensive metals in the world.4 Another chemotherapy drug called Taxol is made from the bark of an extremely rare tree, the Pacific yew. These trees only exist in old-growth forests in the Northwestern United States, and it takes at least 60 pounds of bark to produce enough of the drug to treat just one patient.5 Because this resource is finite, manufacturers must handle their test samples with care. Regardless of the reason for high cost or scarcity of material, many pharmaceutical manufacturers can benefit from small sample testing; the less product you waste during testing, the more product you can put into the hands of those who need these invaluable medications.

small sample testing
Small sample accessories can help you test expensive materials without wasting more product than necessary. Image Source: Shutterstock user Syda Productions

How to Measure Small Sample Sizes

To test an especially small sample size, you’ll need a repeatable measurement method designed accurately analyze your sample size. Many of HunterLab’s spectrophotometers are compatible with specialized accessories that allow you to accurately test small and micro sample sizes consistently. The accessory that you will find most beneficial depends on the type of product you’re manufacturing, what the minimum size of your sample will be and the type of spectrophotometer that you already have in your lab. These may include:

Measuring Powder Samples in Reflectance Mode

If you’re working with powders, you’ll need to modify your spectrophotometer’s port plate in order to get accurate color measurements from a very small sample size. HunterLab instruments that include a Small Area View (SAV) option can be equipped with a smaller port plate as an accessory. In addition to the smaller port plate, you can use a special powder holder that measures about 0.4 ccs of pressed powder. To use this method, simply place your powder sample into the holder, pack it down with the plunger that comes with the accessory, and then place it inside of the port plate, where it will be measured via the clear window on the holder. 

Measuring Solid Samples in Reflectance Mode

If you’re working with any small solid samples, then you’ll need to reduce the size of the port opening on the spectrophotometer. This will allow you to view the sample without a background. Many of HunterLab’s spectrophotometers are able to switch from a Large Area View to a Small Area View automatically, using a motorized component. To use a SAV on your small solid sample, you should operate the instrument via the retroviewer option so that you can ensure that the entire solid sample covers the port opening. Be aware, however, that your sample size needs to be at least as large as the openings (4 mm or 3 mm, depending on the instrument).

Measuring Liquid Samples in Transmittance Mode

If you’re working with liquids, you’ll need a specialized semi-micro cell holder for your samples. HunterLab has a semi-micro cell holder accessory available that includes beam-reducing optics to take accurate measurements of small liquid samples. This accessory needs to be installed in the transmission compartment of the instrument. A typical 10mm pathlength cell requires 3500µL of solution, HunterLab offers mirco and ultramicro cells that can be measured with a little as 300µL of solution.   

HunterLab Innovation

With specialized accessories like smaller port plates, semi-micro cell holders, and powder holders, HunterLab provides reliable solutions for even the most exacting color measurement challenges. Our instruments are designed to meet the high standards set by the pharmaceutical industry, and over the past 60 years, we have been a leader in dependable color measurement of liquid, solid, and powdered medications. Contact us today to learn more about our spectrophotometers, customizable software packages, and world-class customer support services and let us help you select the right tools for your needs.

  1. “Why is Soliris the Most Expensive Drug in the US?”, May 27, 2017,
  2. “How Pill Color Affects Drug Adherence”, May 9, 2016,
  3. “Why is Biomanufacturing So Hard?”, July 15, 2011,
  4. “Why is Platinum in Some Chemotherapy Drugs, and Can We Improve Them?”, April 14, 2017,
  5. “Drug Made from Rare Tree is Approved to Treat Cancer”, December 30, 1992,
The Benefits of Simulating Daylight Using UV Control
simulating daylight
UV control allows you to test the color of your products as they are seen under daylight conditions. Image Source: Unsplash user Breather

Have you ever noticed that printer paper appears even more brilliantly white when you view it outside in the direct sunlight than it does inside under the the warm glow of an incandescent lighbulb? This is no coincidence. Paper manufacturers frequently use Fluorescent Whitening Agents (FWAs) that are designed to absorb UV light, and then re-emit it back at the viewer in the blue end of the visible spectrum.1 This re-emitted light produces a brightening effect on the paper, making it appear even whiter to the naked eye. In addition, FWAs may also compensate for yellow paper coloration or other variations in color. In other words, manufacturers can use UV light, natural light and different-colored light sources to make their products appear even brighter, and thus, more visually-appealing to customers.

However, while FWAs are an essential material in some industries, such as paper, textile, and plastics, they also make accurate color measurement more challenging. FWA-enhanced samples can appear dramatically different in color to the human eye depending on whether the product is viewed outdoors, or under artificial lighting conditions. The color of the light source also has an impact on the appearance of the product. This is one of the reasons UV control is essential for color measurement—it allows you to account for many different lighting conditions, including daylight and indoor environments. Using spectrophotometers with UV control options, you can get a more accurate color reading on your FWA-enhanced products, allowing you to view your products exactly as your customers will see them.

What is UV Control?

The ultimate goal of UV control is to obtain more accurate color readings of your samples under various lighting conditions. In natural daylight conditions, UV control essentially allows you to view the sample as the human eye would see it outdoors. To accomplish this, many spectrophotometers attempt to match the CIE standard illuminant D65. Commonly called the “daylight illuminant,” D65 closely matches the amount of light that you would see on a clear afternoon in Northern or Western Europe.2 Spectrophotometers have the ability to simulate these conditions in the lab, producing a consistent environment in which to test samples.

This is where UV control comes into play. UV control options include the use of xenon light sources, motorized UV filters and calibrated fluorescent standards. Each of these options can dramatically improve the accuracy of your color measurements when testing FWA-enhanced samples. In spectrophotometers, UV control works by allowing you to see products as they appear under natural, UV daylight conditions. This is helpful for industries that use FWAs, as you can measure exactly how the product appears to your customers, even if you measure the product in an indoor, controlled lab setting—it simulates daylight conditions for you.

simulating daylight
Paper manufacturers often use FWAs to enhance the appearance of their products under UV light sources. Image source: Pexels user Tirachard Kumtanom

Achieving Accurate Color Measurements for Whitened Products

One of the most important benefits of UV control is the ability to obtain accurate color measurements for bleached or fluorescent white products. The problem with products that have been dyed with FWAs is that traditional whiteness measurement standards may not be accurate. The FWAs interact with the UV light, which can cause a variation between the whiteness index measurement and how the human eye perceives the color of the product. In other words, the spectrophotometer may not measure the color accurately, according to how your customers will see it. UV control corrects for this by calibrating the spectrophotometer so that it corresponds to a specific UV standard. So, if you wanted to test your product’s appearance under simulated daylight conditions, then you could calibrate your spectrophotometer so that it controls the amount of UV light emitted, allowing you to see your products as your customers will see them under those conditions.

UV Control Methods for Fluorescent Samples

The UV control method that you use to measure whitened products will depend on what type of measurement you want to make. If you want to measure your product as it would appear in outdoor lighting conditions, then you may use UV calibration and fluorescent standards to achieve this. Many of HunterLab’s spectrophotometers offer UV control and are supplied with fluorescent standard calibrated to a Ganz whiteness value traceable to the Hohenstein Institute in Germany. From here, the software in the spectrophotometer automatically reads the fluorescent standard and adjusts the motorized UV filters until the calibrated Ganz value is achieved. You can repeat this process monthly, or whenever you change the instrument’s lamp.

Alternatively, you can eliminate UV entirely, allowing you to view the sample as if it were indoors under incandescent or LED lighting which has limited or no UV content.  To do this, you can insert the spectrophotometer’s UV filters completely and take a measurement of the sample without UV interference. You can then compare this measurement to one made while the UV filter is in its normal position—this should tell you exactly how much impact the FWAs have on the final color of your product. By using one or more of these methods, you can accurately test your fluorescent samples under a variety of lighting conditions, including simulated daylight.

simulating daylight
Many spectrophotometers are equipped with xenon light bulbs, which closely mimic natural daylight conditions. Image Source: Pexels user Pixabay

UV Control Compensates for Lamp Age

In addition to helping you accurately measure fluorescent white samples, UV control can also extend the use of your lamps over time. As your light source ages, its illuminating qualities may change. The bulb often begins to dim, and this in turn can impact the results of your color measurement tests. When you perform UV calibration every week, or whenever you change your light source, your spectrophotometer will adjust to the new conditions, compensating for the difference in light source. If you have a lamp that is capable of flashing one million times throughout its lifetime, this is an essential tool. UV control will ensure that every flash that lamp makes, whether it’s the first time or the 30,000th time, will lead to accurate measurement results.

Achieving Illumination Agreement Between Different Instruments

One final benefit of UV control in spectrophotometers is that you can ensure more accurate readings between multiple instruments. Illumination agreement between different color measurement instruments can be a challenge—an instrument with an older lamp, or one that uses a tungsten bulb may get a very different color reading compared to an instrument with a newer lamp, or one that uses xenon bulbs. In addition, xenon bulbs are a closer match to the D65 standard compared to halogen bulbs, and this will have an impact on how these different instruments measure color. UV control takes some of this variation out of the equation, since you can calibrate for this change of light source in advance. The result is a more accurate color measurement protocol that works well for a wide range of industries, and that is designed to last for the entirety of the instrument’s lifetime.

HunterLab Options

HunterLab carries a wide variety of spectrophotometers that contain built-in UV control options. The LabScan XEs, UltraScan Pros and the UltraScan VISes are all capable of accounting for UV light variations. Moreover, many of these instruments take UV control one step further—you can adjust the spectral distribution of the xenon lamp to more closely match the D65 illuminant, meaning that you can achieve even more accurate color measurements. Contact us today to find out more about our spectrophotometers and how UV control can enhance your quality control processes.

  1. “Fluorescent Whitening Agents”,
  2. “Illuminant D65”,
Spectrophotometric Color Measurement Helps Optimize Appeal of Over-the-Counter Medication
over-the-counter medication
The color of OTC medication influences how consumers perceive its quality. Image Source: Shutterstock user Corinna Haselmayer

A man suffering from a bout of heartburn walks into his neighborhood grocery store hoping to find an antacid that will relieve his symptoms. He heads straight for the over-the-counter medication aisle, but he sees that there are almost two dozen different brands of antacid sitting on the shelves. He isn’t sure which one to choose. Should he go with the antacid tablet that is a calming shade of pale pink? Or is the bright green tablet a better choice?

According to research, many customers in this position would pick the pale pink option. In a study published in the International Journal of Biotechnology in 2010, researchers at the SIES College of Management Studies found that people were more likely to perceive a pink medication as sweet and pleasant, whereas they perceived green medication as sour or bitter.1  This may be because many people associated the color green with acidity, which would be unappealing for those suffering from acid reflux.

This study is part of a growing body of evidence showing that color can dramatically impact perception of medication efficacy and overall user experience. As a result, color becomes a significant factor in consumer behavior and, consequently, the commercial success of medications. This phenomenon is particularly relevant for over-the-counter medication manufacturers. Unlike prescription drugs, which are recommended to patients by doctors, over-the-counter (OTC) medications rely heavily on consumer perception for sales. As a result, OTC medication manufacturers must rely on spectrophotometers to ensure that their products are as aesthetically pleasing as they are effective.

over-the-counter medication
With so many OTC medication brands on the market, it’s important for manufacturers to create colorful products that stand out. Image Source: Shutterstock user mayakova

The Impact of Color on Customer Perception, Adherence, and Habits

Households in the United States spend an average of $338 per year on OTC medications, and 81% of adults say that they use OTC drugs as a first response to most medical problems.2 However, the OTC drug market is competitive and pharmaceutical manufacturers must take color into consideration when developing their products in order to ensure optimal appeal, as color consistency has a significant impact on consumer behavior. For example, one study published in JAMA Internal Medicine in 2013 found that patients who have epilepsy were less likely to adhere to their to their medication schedules if the color of their medication changed during the course of treatment.3  In fact, patients were 53% less likely to take their medication on time if they were given a different-colored pill than they were used to, potentially compromising treatment outcomes. As such, it’s critical to ensure color consistency in all medication products to facilitate adherence.

Additionally, consumers associate different colors with treatment of different conditions. In a groundbreaking study, psychologist Dr. Max Lüscher examined the connection between drug color and the treatments people associated with them.4 While conducting his famous color psychology test, Lüscher found that people most commonly associate orange or yellow with stimulant drugs, olive green or light brown with laxatives, and cough suppressants with light blue or maroon. As a result, some OTC drug manufacturers choose to create products that align with these color associations; colors act as a kind of visual shorthand for the consumer.

In some cases, drug manufacturers can even reinvent consumer color associations. When Pepto-Bismol first hit the market nearly 100 years ago, it was an unusual shade of pink that consumers hadn’t seen before. The source of the hue was the product’s active ingredient, bismuth subsalicylate, which is naturally pink in color.5 While the pink color became strongly associated with the brand itself, it also came to signify antacid medication as a whole. Today, many antacid manufacturers will go out of their way to dye their products pink, even if they use active ingredients that are a different color. This is because studies have found that using a color other than pink can confuse customers, who have come to so strongly associate pink with antacid medication that they may believe non-pink medication is used to treat a different ailment.

over-the-counter medication
Pink medications are often perceived as tasting sweeter compared to green, red, orange or yellow medications. Image Source: Shutterstock user Yuriy Golub

Spectrophotometers Can Help You Achieve Color Consistency

Spectrophotometers play a critical role in creating the ideal pharmaceutical hues and maintaining them from batch to batch, assisting OTC drug manufacturers throughout product development and manufacturing processes. First, pharmaceutical manufacturers can use spectrophotometry during the formulation stage in order to develop the perfect color for every product in their line. Using spectrophotometric data, you can set unique color tolerance standards for each product. From here, your future products can be compared to this guideline to ensure color consistency. Whether you formulate a dusty pink-colored antacid or a bright yellow allergy medication, the spectrophotometer’s software can tell you with great accuracy whether your product falls within the color tolerance that you’ve set. As such, operators can be quickly alerted to unwanted color variation, allowing for corrective action. In pharmaceuticals, this is essential not only for aesthetic reasons but because incorrect coloration could indicate incorrect formulation or processing, both of which may have serious health implications.

OTC medications, of course, come in many different formats, from pressed pills to capsules to liquids, which each has their own unique properties that influence color measurement. As such, the spectrophotometer you choose must be appropriate for the material with which you are working:

  • Liquid Medications: The color of liquid medications can be measured using reflectance or transmission instrumentation depending on whether the product is opaque, transparent or translucent. HunterLab’s UltraScan Pro, UltraScan VIS and Vista instruments are all capable of measuring liquid products and each have unique benefits.
  • Pills and Capsules: When measure pills and capsules , you’ll first need to consider whether your products are opaque, translucent or transparent, just as you would with a liquid product and choose either a reflectance or transmission instrument suited to your needs.
  • Powdered Medications: For color measurement of powdered medications, or for powders that will eventually be pressed into pill or cream form, a Directional 45°/0° reflectance geometry is preferable as it measures color the way the eye sees it. Hunterlab offers a range of instruments designed to handle loose powders and pressed powder plaques, including the LabScan XE, includes an automated zoom lens that allows you to measure very small samples.

With the right instrument, you can achieve greater insight into pharmaceutical color than ever before and implement the most rigorous color quality control processes possible to promote product appeal, ensure product safety, and facilitate customer adherence.

HunterLab Reliability

For more than 60 years, HunterLab has worked closely with the pharmaceutical industry, helping manufacturers establish and adhere to color standards. Using advanced spectrophotometers and color measurement software, OTC drug manufacturers can now ensure that every product is correct and consistent in appearance, whether you are working with liquid medications, pills, capsules, or powders. Contact us today to find out more about our state-of-the-art spectrophotometers and let us help you find the perfect tool for your unique needs.

  1. “Color Psychology in Medicine”,
  2. “Statistics on OTC Use”,
  3. “Variations in Pill Appearance in Antiepileptic Drugs and the Risk of Nonadherence”, February 11, 2013,
  4. Pharmaceutical Dosage Form, April 19, 2016,
  5. “Packaging Defines the OTC Market”, 2005,
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