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Color surrounds us every moment of our lives and affects our emotions, behaviors and beliefs in large and small, conscious and unconscious ways. Color can set a mood, warn us of danger, give us critical information and even bring us joy. Despite the universal presence of color, describing it remains elusive, in part due to variations in color perception from person to person and in part due to a lack of descriptors for each of the millions of shades seen by the human eye.

Instrumental color measurement moves beyond the limits of human perception and vocabulary and allows us to capture color information as objective data, creating a common language of color that is essential for communication within and between industries around the world, ranging from food and beverage to pharmaceuticals. The two most advanced color measurement instrument types are colorimeters and spectrophotometers, both of which use sophisticated technologies to accurately and precisely quantify and define color.

While closely related, these instruments have unique qualities that may make one more suitable than the other for a particular type of measurement. Understanding the characteristics of a colorimeter vs. spectrophotometer can help you select the best tool for your application.

What Is a Colorimeter?

A colorimeter is designed to perform a type of psychophysical sample color analysis, which means its measurements correlate to human color perception. In other words, it is designed to see color the way we do.

Its results are direct and read as tristimulus values. A tristimulus value is one that identifies a color with characters that represent different dimensions of its visual appearance. A tristimulus value may contain values like X, Y and Z or L, a and b. The “gold standard” for tristimulus colors is the CIE Color System, developed by the International Commission on Illumination — the CIE in the title stands for the French version of their name.

There are a few unique components involved in a colorimeter.

• Illuminant: The illuminant represents a specific light source, such as daylight or incandescent light, to project consistent brightness onto the object. In a colorimeter, an illuminant is fixed.
• Observer: The standard observer offers a specific field of view with which to analyze the colors. A colorimeter usually uses a 2-Degree Standard Observer, which is suitable for color evaluation and quality control.
• Tristimulus absorption filter: The absorption filter isolates specific wavelengths to be applied to the sample.

Types of Colorimeters

Colorimeters are essential in determining color objectively and accurately. Their different varieties measure color to varying depths and degrees. Types include:

• Densitometers: These measure the darkness level, or density, of semi-transparent material.
• Photometers: Color photometers measure how color is transmitted and reflected.

How Does a Colorimeter Work?

A colorimeter’s usage is often based on the Beer-Lambert law, which tells us that the concentration of a solute is proportional to its absorbance. The colorimeter starts with a simple light source. With the help of a lens and tristimulus absorption filters, the beam of light becomes a single, focused wavelength which then moves through to the sample solution. On the other side of the solution is a photocell detector that identifies how much of the wavelength got absorbed. The detector is connected to a processor and digital display that offers a readable output of the results.

Now that you know how it works, let’s take a look at the pros and cons of a colorimeter.

The human eye is an amazing tool, with the ability to distinguish millions of color variations. Amazingly, science has emulated the human eye’s perception of color difference and translated that information into colorimetric technology. Spectrophotometers quantify color difference in the same way our brain processes color through light absorption and reflection, and utilizes this data for a variety of scientific and industrial applications.

The human eye has amazing abilities to differentiate color and science has transferred this technology to precise and objective analysis through spectrophotometric instrumentation. Image Source: Flickr user Liz Foreman

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.

Achieving the best color measurement results depends on choosing the right tools, including the best sample holders. Image Source: Shutterstock user Rattiya Thongdumhyu

In a broad range of industries, obtaining accurate color data and maintaining color consistency of liquid products is essential. This is particularly true when color has a significant impact on both the functionality and appeal of a liquid, which is why spectrophotometric color measurement is an integral part of quality control protocols for virtually endless array of products. However, the spectrophotometer is not the only factor to consider when establishing analytical methods; you must also consider the suitability of spectrophotometric accessories.

This is where a common question arises: should I use glass or plastic sample holders? Both glass and plastic sample cups are versatile, widely available, and can often be effectively employed for reliable color measurement of liquids. Therefore, when choosing which of two types to use, it is important to consider the pros and cons of each material.

Glass vs. Plastic Sample Holders

At the most fundamental level, the question of whether you should use a glass or plastic sample holder to measure the color of a liquid product has a simple answer: either option is likely to be sufficient. There are certain benefits to glass sample holders that render them slightly preferable to plastic sample holders, but if plastic sample holders are used properly, they can often be just as effective for color consistency measurement; as long as you are familiar with the potential pitfalls of plastic sample holders, they can achieve the same level of reliability as glass sample holders. However, there are certain circumstances in which it may be optimal to take advantage of the benefits of glass sample holders.

Choosing the right sample holder can ensure accuracy of color measurement and enhance safety in your lab. Image Source: Shutterstock user science photo

Peanut butter has a uniquely American history and consumers have strong preferences for how peanut butter should look. Image Source: Flickr user Denise Krebs

When I lived in London, one of the things I missed most about the United States was peanut butter. Yes, there was peanut butter in the UK, but it was different and it wasn’t the sort of difference you could look past. And, as I came to find out, I wasn’t the only one who felt that way. In fact, American peanut butter was a hot commodity; whenever someone would go home on holiday or have visitors from the US, we would put in our peanut butter orders and wait impatiently until we could get our hands on what we knew and loved.

It makes sense that Americans have a unique relationship with peanut butter. It was, after all, John Harvey Kellogg, a physician and vegetarian, who began giving his patients nut butters in the 1890s to provide them with a healthy, easy-to-eat source of protein.1 Simultaneously, he began supplying peanut grinders to health food stores, allowing a relatively small market of niche, expensive peanut butters to flourish.

Mass commercialization, however, didn’t happen until the 1920s, when Joseph Rosefield introduced the use of hydrogenated fat in the peanut butter manufacturing process, preventing oil separation and drastically increasing the appeal of the product. Rosefield’s invention came just in time; “as the scarcity of meat [during WWII] required citizens and soldiers to seek protein alternatives.”2 From that point on, peanut butter took off. Today Americans spend over $1.8 billion on peanut butter annually – more than any other nation in the world – and over half of peanuts grown in the United States are destined to be made into peanut butter.3

This history is noteworthy because it informs how Americans approach peanut butter and guides the purchasing decisions of consumers. Peanut butter is not seen as an exotic food eaten on rare occasion, but as a staple that is consumed throughout life, something we remember from our grade school lunch boxes, something we eat as comfort food, and something that has become inextricably linked to our culture. It is familiar and beloved. As such, consumers have very specific expectations of peanut butter products and strong preferences regarding what it should taste, look, and smell like, preferences that have typically been ingrained from childhood. The color of peanut butter in particular is of utmost importance when it comes to influencing consumer choice and experience.

The color of peanut butter is an important indicator of quality and reflect both the quality of raw ingredients and correctness of processing.
Image Source: Pexels user stock.tookapic.com

Stout is so opaque that its red hues take on a rich, deep brown color. Image Credit: Flickr user a.dombrowski

My best friend is a diehard IPA fan and up until recently, I’d never seen her drink anything darker than a red ale. Whenever I’d offer her a taste of Guinness, she’d always shake her head and say, “Dark beer is too heavy and bitter.” One day, I decided to take her to one of Portland’s annual beer festivals, hoping I could change her mind about dark brews. When we got there, the festival’s dark beer list alone boasted close to 100 separate labels, ranging from porter to stout. After a lot of persuasions, she agreed to try the black lager that I recommended. She took a sip, raised her eyebrows in surprise and said, “I had no idea that dark beer could taste this light!”

Beer opacity has a massive impact on how drinkers perceive your brew’s flavors. Your customers usually look at the color of the brew and how translucent it is before they consider any other factor like smell or taste. That’s why it’s so important for breweries to ensure that the opacity of their beer matches its traditional style, giving customers the best impression before they take their first sip.

Why is Stout So Opaque?

Like coffee, beer opacity often comes from how long you roast the ingredients. Generally, a dark roast will give you an opaque, almost jet black beer that tastes like coffee or chocolate, whereas a light roast will give you a golden, translucent color and “breadier” flavors. However, it’s not always this simple. If your brewery uses black patent malt1, you’ll also get a dark opacity in the final brew, but the flavors will be completely different than a heavily roasted barley beer. Stout brewers use trace amounts of black patent malt to give the beer a deeper color while retaining light, bready flavors underneath. This is why that black lager that my friend tried tastes more like a Belgian pale ale than a frothy glass of chocolatey stout — the opacity of the beer has little to do with how it actually tastes.

How long you roast the barley and the type of malt you use can impact the beer’s opacity. Image Credit: Flickr CC user Dylan Stark

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.

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