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Many quality control (QC) professionals in manufacturing focus on variables like formulations, processing impacts, and contamination when considering which factors cause color alterations in their products. But for certain applications and in extreme environments, one unseen variable can cause equal damage to color consistency — temperature.

Even minor temperature variations can quickly ruin a batch or turn QC into expensive guesswork. The fluctuations can influence a sample's optical properties, alter light interactions, and impact measurement data reliability. As a result, maintaining color confidence in extreme conditions requires both strict protocols and powerful equipment to mitigate the environmental variables and uphold data integrity.

What Causes Temperature to Alter Color Measurement Results?

Understanding how temperature alters measurement results requires examining both the material-level changes and environmental factors that impact spectrophotometric analysis.

Thermochromism

Thermochromism is the phenomenon of a material exhibiting a reversible change of color in response to temperature changes. For example, think of novelty cups that turn from blue to green when filled with hot or cold liquid. This color change isn't the result of user error, but instead a temporary alteration in the material's optical properties that causes the material to reflect or transmit different proportions of light across the visible spectrum.

As the temperature of the contents starts to normalize to room temperature, the original color gradually returns. In such products, these color alterations are the goal for the desired effect. In others, thermochromism is a consequence to avoid, making consistency the key to preventing it. 

It's important not to confuse thermochromism with thermal degradation, an irreversible color change arising from extreme temperatures that can impact long-term color stability.

Environmental Instability and Material State Changes

Extreme temperatures can trigger physical changes in many samples that impact color perception, depending on the application. For example, thermal expansion and contraction can alter surface textures, changing how light reflects off the material and, in turn, the resulting measurements.

Measuring the color of hot liquids poses similar issues. As temperatures rise in these samples, bubbles and vapor often form that cause light to scatter differently, influencing appearance.

Additionally, temperature fluctuations can create secondary effects, such as the formation of condensation on sample surfaces. This excess humidity demands well-defined surface preparation protocols to ensure accurate readings.

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. 

The Vista spectrophotometer includes a smart touchscreen display that requires very little operator training. Image Source: HunterLab

We rely on our smartphones for just about everything, from navigation to communication. Messaging apps and texting allow us to instantly talk to everyone from our closest friends to distant relatives, all without ever leaving the house. News and entertainment are just a few taps away, and we have the ability to research any subject imaginable within seconds. All of this is made possible in part by intuitive interfaces and operating systems that make it easy to use this advanced technology on a daily basis. In this sense, smart technology blends seamlessly into our lifestyles, both becoming part of our everyday routine and making that routine easier than ever.

Just as smartphones have changed the way we communicate and interact with the world around us, smart spectrophotometers are changing the possibilities of spectrophotometric color measurement and revolutionizing operators’ work styles. Smart screen displays, advanced data management software, and network communications have made smart spectrophotometers easier to use, enhancing usability of data and efficiency of color analysis.

However, while there have been significant advances in smart spectrophotometer technology, many operators still use outdated instruments. Using a spectrophotometer without state-of-the-art features is a bit like being forced to make calls from a rotary phone—outdated technology slows down workflows and leads to manufacturing inefficiencies and errors. This is why you should consider making the switch to smart spectrophotometers in your lab. Smart technology improves productivity, data management, and operator learning curves, allowing you to maximize your operators’ time and, ultimately, produce higher-quality products.

Smart spectrophotometers like the Aeros improve workflow by speeding up the sample preparation process and making it easier to record measurements. Image Source: HunterLab

Chemical analysis is an intricate part of our everyday lives. From the water we drink to the food we eat to the fuel we put into our car, nearly everything we consume has undergone some form of chemical analysis before use. Although it’s likely not something we consider as we go about our daily activities, it’s a vital aspect of the production process for many things and something we all rely upon for quality assurance.

Petrochemical manufacturers know that chemical analysis is one of the most important steps in the monitoring of chemical compounds in the petroleum refining process. It is also one of the most unique and difficult processes to quantify and analyze. The ability to detect color changes is an important step in the process for identifying contaminants and impurities. With the right technology, the challenges of chemical analysis can be met.

Clear liquids are classified based on visual comparison.

Applications of Color Measurement in Petrochemicals

Petrochemical production results in a number of goods and materials that are dependent on accurate chemical analysis. From crude oil to the most refined petrochemical products, the manufacturing process relies on color technology to help with interpreting data, differentiation, and classifying petrochemical compounds. Petrochemical materials cover a wide range of products such as solvents, adhesives, plastics, resins, fibers, elastomers, lubricants, and gels. Each compound can vary from transparent to translucent to opaque, and accurate measurement is contingent upon the highest quality of instrumentation to measure transmittance or reflective materials.

The products that result from petrochemicals are numerous and varied. Image Source: Flickr user snowlepard

The petrochemical industry has greatly benefited from the use of color technology and spectrophotometers, and the ability to detect color changes throughout the refining process is an important step in identifying possible contamination. The ability to recognize even the slightest changes throughout processing helps to alleviate any impurities that may affect the quality of the final product. Detecting changes is crucial in monitoring and identifying any needs for re-distillation throughout the refining process.

A food dye is a chemical substance that uses artificial color to enhance the appearance of food. Though dye may make drinks, candy and other food look better, many are concerned about adverse side effects. Learn more about why we color food and how it impacts health.

The History of Food Coloring

Food coloring has been around for centuries. It was first developed around 1500 B.C. using saffron or wine. The early Romans used these natural options as well as mulberries, flowers, carrots, beets and pomegranates. The first artificial food coloring was made from coal tar in 1856. Food dyes are petroleum-based today.

Why Do We Color Food?

Food dye changes the food’s color and appearance to look more appealing to the consumer. Some food processing can remove food’s natural color. Dye adds it back so the food looks as expected. Food manufacturers typically prefer artificial food dye to natural options because it has more vibrant colors, longer shelf life and a lower production cost.

The Health Effects of Food Coloring

The safety of food coloring is a long-debated topic due to the concern about negative health effects. Out of the hundreds of developed food dyes, a select few are deemed safe for consumption because they have been tested for toxicity in animals. Yellow 5, Red 40 and Yellow 6 are the most common.

Food dye safety can be confusing because different countries have different laws about the same food coloring. For example, The Food and Drug Administration (FDA) in the United States and the European Food Safety Authority (EFSA) agree that food coloring is not harmful. However, there are food dyes approved by the FDA but banned by the EFSA, and vice versa.

In the past 100 years, the amount of food coloring used in food has increased drastically. This shift is due in part to manufacturers’ growing emphasis on making food look more appealing, last longer and attract as many consumers as possible. The U.S. Food and Drug Administration (FDA) imposes strict regulations and standards for the approval of artificial food dyes and how food producers and manufacturers are permitted to use those dyes in their products. Learn more about food color standards established by the FDA, including what technology your business can use to operate within regulation.

What Is Food Coloring?

Food coloring and food dyes are chemical substances used to alter or enhance the appearance of a food product. Three color additives make up 90% of all used food dye — Red 40, Yellow 5 and Yellow 6.

Using color additives or dyes is not a new technology. Natural food colors were used to color wine as early as 300 B.C. Early dye experimentation included naturally occurring color found in some spices and metal oxides, like saffron and copper sulfate.

The first synthetic organic dye — called mauve — was discovered in 1856. Mauve was the first of many discovered synthetic dyes produced via coal processing, earning them the title “coal-tar colors.” Federal regulation of color additives began a few decades later, in the 1880s.

What Is Food Coloring Made Of?

Artificial food coloring is derived from petroleum. There are three possible classifications for a food dye:

• Straight colors: Straight colors are free from most impurities and have not been mixed or chemically altered with other substances.
• Lakes: Lakes are the product of a chemical reaction that takes place after combining a straight color with precipitants or substrata of things like alumina, titanium dioxide and zinc.
• Mixtures: Mixtures are made by combining a color additive with another color additive or a non-colored diluent, which produces no chemical reaction.

Appropriate color measurement tests can help you create fiber cement siding that is as beautiful as it is durable. Image Source: Shutterstock user Kiattisak Thongtawee

Fiber cement siding—a sturdy combination of wood pulp, fly ash, portland cement, and water—was first introduced in the construction industry just 25 years ago.1 Since then, it’s become one of the most popular materials that architects use for their projects. Almost 15 percent of all new homes have fiber cement siding, in part because this material is so durable and versatile. Although this material can be made to look just like brick, stone, or wood siding, it is actually far stronger than wood or vinyl materials, and less expensive to make than brick or stone. Quality fiber cement siding is fire resistant, termite-proof, rot-proof, and can withstand extreme weather conditions like heavy rain, strong winds or fluctuations in temperature.

But in order to achieve both the durability and beauty of fiber cement siding, manufacturers have to use appropriate color measurement methods at different points in the manufacturing process. Siding color is often the first thing that visitors notice when they look at a house, which is why it’s so important to test for color accuracy before you sell your products to customers. Even subtle inconsistencies in color could make fiber cement siding appear cheaply-made or weather-worn, and will negatively impact the overall appearance of the house. By using spectrophotometric color measurement during manufacturing, you can ensure that every piece of fiber cement siding meets your exacting standards and that your final product will appear beautifully-crafted.

Unpainted fiber cement siding is usually light grey in color. Image Source: Wikimedia user Michael Holley