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Selecting the right spectrophotometer requires understanding the optical geometries available in to ensure the instrument is compatible with your needs. Image Source: Unsplash user Sean Brown

Spectrophotometers have changed the way color is evaluated and are an integral part of product research, development, and manufacturing across industries and around the world. The advanced spectral analysis made possible by these instruments allows for unprecedented color quality control while simultaneously increasing efficiency and offering significant opportunities for cost-saving. However, the specific type of spectrophotometer you select can have a great impact on your color measurement abilities and results.1 Choosing the correct instrument for your purposes requires an understanding of optical geometries and how they affect your ability to obtain the data you need.

A 45/0 spectrophotometer automatically accounts for geometric attributes like gloss to measure color appearance. Image Source: Flickr user Nick Pateman

At my new quality assurance job, one of our product quality checks is to measure the color of our product and to ensure that we are producing our product that is within a preset acceptable color range. We use an instrument, a spectrophotometer, that reports Hunter L, a, b; XYZ, and L*a*b scales. I’ve always thought that color was measured in terms of RGB, like the way computer monitors and TV screens describe color. I’ve even created custom colors for fonts on my computer by manually adjusting the RGB quantities. Can someone explain why we would measure color using Hunter L, a, b; XYZ, and L*a*b instead of RGB?

It depends on what you want. Do you want White, Yellowish White, or Bluish White?

In simple terms, the primary difference between CIE Tristimulus Scales (Hunter L, a, b; XYZ, and L*a*b scales) and RGB is their purpose within the color world. RGB is a device dependent method of producing color and is not exact enough to be used to describe a color for quality control purposes. CIE XYZ color scales represents the true color of an object, while RGB describes a flat solid color representation of the average color of an object is displayed on a screen. One is used to provide color directionality (RGB), the other is used to precisely quantify a color (Tristimulus values). let’s illustrate…

Let’s take a drive to the Lincoln Memorial

Let’s pretend the Lincoln Memorial is not a physical object but rather a specific color, let’s say white, since in fact it is made of a very specific white concrete. To get there, should I use RGB or Tristimulus values? This will depend on how close to the Lincoln Memorial, or its specific color of ‘white’ you want to get. Using RGB to measure the color white and expecting analytical precision would be like trying to get to the Lincoln Memorial without the exact address and a GPS/map to guide you. While you may know that the Lincoln Memorial is located in Washington D.C., getting to the specific address would be a challenge.

RGB is very much like this in that you might know the general area of red, blue, green, or in this case ‘white,’ but getting to a precise color takes more than a general direction. Much like GPS, which uses three-dimensional physical coordinates that can guide you to within three feet of the desired address, CIE Tristimulus scales provide three-dimensional color coordinates to give you the exact address of a specific color with extreme precision. While RGB might drop you off on the Mall without any further direction, tristimulus coordinates will direct you precisely to a specific color with decimal precision, much like GPS will guide you to the Lincoln Memorial within three feet.

“Amber beer” is a catchall term that refers to any medium-opacity beer, ranging from bright red to caramel brown in color. Image Credit: Unsplash user Julia Nastogadka

I used to believe that all amber beer looked about the same: a bold, almost cranberry-colored brew with a hint of frothy, cloudy opacity. Everything changed for me when I went to my first amber beer tasting. I saw a long tasting table lined from end-to-end in every amber style imaginable, from the bright red ale that I was used to seeing, to the deep caramelized browns of American amber ale. It was clear that the brewers were proud of their glasses — each ale had an unmistakable color unlike any other sitting next to it. When I looked closely at each glass, side-by-side, I could see the subtle differences between them. I saw flecks of gold in one light red beer, whereas its neighbor had deeper, almost rose-like color qualities.

These subtle differences in color and opacity make your brew absolutely unique. That’s why it’s important to measure your amber beer’s opacity and color consistency throughout the brewing process. When it comes to red or amber ale, your color is your signature, and it will keep your customers coming back year after year.

Brewers often find it difficult to measure their amber beer’s color by eye, since this beer style has a wide range of possible color variations. Image Credit: Pixabay CC user PeterKraayvanger

To help photographers and videographers realize their vision, lens filters must be consistent in color and free from contaminants. Image Source: Shutterstock user Layue

Colored lens filters are essential tools for photographers and videographers. These accessories improve the quality of their images and help them achieve the aesthetic they are seeking to create, expanding both technical and creative boundaries. However, this can only happen when the color of the lens is consistent and the product is free of contaminants such as dust or other types of flaws in the glass. If the lens is too hazy or the color is too light or dark, it could compromise the quality of the final image. To prevent this, manufacturers of colored lenses must rigorously test their products for color consistency and clarity throughout the production process. When you perform color quality control tests throughout your manufacturing process, you’ll ensure the integrity of your products, refine your production processes, and help your customers realize their artistic visions.

The Importance of Color Consistency and Clarity in Lens Filters

Different lens filters have very specific uses in photography and videography and are sought out to create unique effects that are not possible with conventional lenses. But if the filter is off in color by even a few subtle shades, it could significantly impact the image’s appearance. This is why color consistency is critical for lens filter manufacturers to achieve.

For example, UV filters for cameras are typically clear, but filters that contain a heavier coating of UV filtration will start to look amber in color.1 In fact, if you want your product to filter out as much UV light as possible, your filter should appear fairly dark. If your filter appears almost colorless, however, it may be a sign that you haven’t coated the filter properly and the level of UV protection may be diminished. This can significantly impact the functionality of the filter and create unwanted—and unappealing—color shifts. For example, on a sunny day when the camera is exposed to a great deal of UV light, a blue haze may appear in the final image if UV light is not properly filtered out. Similarly, skylight filters are typically pink in color because they counterbalance the blue bias that film stock typically has. However, this requires a delicate balance; if your filters are too pink, they will make all of the blue tones in the image disappear, whereas if the filters aren’t pink enough, they won’t effectively counterbalance the blue tones in the film. This is why it’s important to get the color just right on your lens filters.

Unfortunately, achieving the right lens color can be difficult, as you must dye the lacquer the same color from batch to batch and you also apply this lacquer in a consistent layer to create the colored film. If you fail to dye the lacquer properly or you apply the lacquer in uneven layers, it could cause the color of the lens filter to appear inconsistent. Additionally, haze and contaminants in the glass can impact the appearance and functionality of the product. For instance, if you use thick glass, you’re much more likely to have air bubbles or other flaws in the product that will show up on film. If you use colored polarizing filters (made from plastic) that you place between two layers of glass, contaminants may come between the glass and the colored film, resulting in a permanent flaw. Other factors like improper formulation and even the oils from your hands can make the lens filter appear hazy. This cloudiness, regardless of the source, will have an effect on the final image; the unwanted particles in the lens will scatter the light when it hits the lens’ front element, and this could cause a stray lighting effect or result in a blurry image.2

To ensure that your lens is manufactured correctly, you should test your materials for color and clarity throughout the manufacturing process. Using a spectrophotometer, you can ensure that the color of your lenses is consistent from one batch to the next and that your glass is free of any potential contaminants.

What happens when the blue on Line A doesn't match the blue on Line B? Or when today's production run doesn't match yesterday's? In manufacturing, consistency equals quality. Nowhere is that more visibly evident than in your product color, where consumers will immediately notice any discrepancies. As you scale production across lines that span different facilities — and sometimes even continents — ensuring color harmony can become increasingly complex.

Understanding the importance of consistent color, knowing the challenges to achieving it, and learning how you can attain it can help you develop effective color-control strategies for your production processes.

Why Is Color Consistency Critical?

Inconsistent color has real-world impacts on your brand reputation and bottom line. When color is repeatable and consistent, you benefit from:

• A better brand perception: Customers have fewer reasons to question your quality or your product's desirability, flavor, freshness, and safety. 
• Fewer rejects and less rework: Goods that meet your customers' color specifications and expectations are less likely to result in costly rejects and rework, saving you time, money, and resources.
• Higher conformance with industry standards and regulations: Certain products and industries have strict color standards or regulations, such as pharmaceuticals and food dyes. Consistent color helps ensure your goods conform to the required frameworks and meet safety requirements.

What Are the Challenges of Achieving Consistent Color?

When production scales across multiple lines and facilities, several key challenges to color consistency arise:

• Raw material variations: The color and quality of raw materials often vary, especially when suppliers differ due to geographic location, availability, or supply chain diversity. Batch-to-batch inconsistencies also frequently occur in the plastics industry, where dynamic concentrations of recycled polyethylene terephthalate (rPET) in raw materials can dramatically impact final appearance.
• Influences in the production environment: Facilities may experience different environmental conditions, from humidity to heat and more, that can contribute to color alterations. Equipment may also vary widely and cause color inconsistencies.
• Variations in process parameters: If facilities differ in their production workflows, methods, or techniques, color consistency becomes more challenging. For example, variations in key process parameters like time and temperature will lead to differing color outcomes.
• Outdated color assessment approaches: Relying on antiquated measurement techniques like visual color comparison increases the potential for inconsistencies. This approach is too subjective, unreliable, and error-prone to uphold consistency effectively.

Color plays a significant role in communicating food quality. Consumers can easily identify an underbaked or overbaked cookie by its abnormal color and texture, knowing these elements will impact its taste. On the other hand, individuals will associate a perfectly caramelized cookie with a high-quality product that likely tastes great. 

How a cookie looks directly impacts consumer buying habits. You can use a color spectrophotometer to measure the color of your cookie samples to ensure they project a consistent and desirable appearance.

Challenges of Measuring Cookie Color

While measuring cookie color is vital for producing a high-quality product, this process can pose several challenges to manufacturers:

• Irregular texture: Cookies have many inconsistent characteristics that make color analysis more difficult, such as their varying shapes, sizes, and highly textured surfaces. To the naked eye, it's nearly impossible to make an accurate color determination.
• Time commitment: Large-scale cookie manufacturers must analyze thousands of cookies each year. Measuring the color of cookie samples one at a time can be extremely time-consuming and labor-intensive.
• Equipment wear and tear: Normal wear and tear can impact your color measurement device's performance, leading to inaccurate measurements. 

Grains are integral to our everyday diets, from rice and flour to cereals, baked goods, and pasta. The color of raw grains contributes directly to their nutritional value, while the color of final goods can influence consumer buying preferences and quality perceptions. Understanding and following industry standards for grain color helps manufacturers maintain quality control, reduce waste, and boost customer satisfaction.

Applicable Color Standards in the Grains Industry

The United States Department of Agriculture is the main government oversight body for raw grains, and its color standards are used for classification and grading. Color can also help determine a grain's suitability for a specific application, as color variances can indicate damage that falls outside allowable tolerances for certain purposes.

The Cereals and Grains Association is the primary industry organization that develops color standards for grain manufacturers and processors. For example, the association has established color benchmarks and measuring methods for pasta products and durum flours. These standards are also compatible with those issued by AOAC International, which upholds standards across the broader agricultural chemistry field.