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New polymer products continue to flood the market, and there seems to be no end to the continued growth in plastic manufacturing. In 2024, the global molded plastics market reached a value of $541.2 million. Experts predict a compound annual growth rate of 7.5% over the next decade, which means the market's value will surge to over $1 billion by 2034. In this booming market, competition with large manufacturers may seem daunting, yet small business continues to thrive.

To stay competitive among these giants, choosing the right spectrophotometer for plastics is often the difference in product efficiency and quality. Understanding the value of color measurement in plastic production is the first step toward optimizing growth and increasing sales overall.

Utilizing Spectrophotometric Instrumentation in Plastic Production

Modern spectrophotometers measure more than the tristimulus values captured by basic equipment. They offer spectral measurement capabilities and can quantify appearance by considering the influences of gloss and texture on perception. This technology makes them an ideal choice for many plastics, which often feature various shapes, textures, and opacities.

Sample types determine the right measurement techniques for accurate color data, so understanding these characteristics that drive your approach is the first step to utilizing your color measurement solutions. For example, accurate color quantification for transparent plastic preforms requires measuring via transmission, while opaque plastics require reflectance measurements.

The device’s geometry is also critical to accurate appearance data capture. A directional 0°/45° geometry illuminates the sample at a 45° angle, with the viewing angle set at 0°. Scientific studies show that these geometric principles provide the truest representation of visual color perception.

Today’s spectrophotometers/colorimeters are available in portable, benchtop, and online models, designed to monitor color variations and changes in real time, from start to finish. Even slight alterations in color can be detected easily and allow for simple changes to be made at any stage of production, saving wasted materials, time, and money. These simple tools are beneficial for efficiently and effectively creating quality products and increasing sales.

Spectrophotometric Applications in Plastic Manufacturing

The variety in plastic shapes, sizes, and colors can present color measurement challenges. Nonuniformity, gloss, shape, and size can all affect color quantification, so choosing the right solution is the first step in developing consistency and quality in polymer products.

Not only are spectrophotometers/colorimeters effective for enhancing the quality and production of molded plastics, but their versatility also extends to many other areas of plastic manufacturing. For example, even nonuniform plastic pellet samples and recycled polyethylene terephthalate (rPET) can be accurately measured with this equipment. Doing so helps to ensure uniform and consistent pellet color, which is used in extrusion and injection molding and directly affects final color quality.

Other spectrophotometric applications in plastics processing include quantifying color data in:

• Opaque plastic enclosures
• Opaque plastic plaques
• Opaque plastic films
• Opaque sheet plastic
• UltraDark plastics, such as deep blues, dark charcoal grays, indigos, and blacks
• Vinyl siding

From the beginning stages of plastic production to the final stages of color analysis in sample plaques, spectrophotometry ensures consistency throughout every step of manufacturing. The simplicity and accuracy of today’s advanced instrumentation take the guesswork out of the process, increasing both production and quality overall.

You spot a batch of roasted cashews and think they look perfect—but the flavor testers disagree, and shelf life is inconsistent. If your QA team relies on visual checks, you’re working with blind spots. Inconsistent roast color means wasted product, unhappy customers, and lost revenue.

Here’s how two tools from HunterLab—Aeros and SpectraTrend HT—help you hit your color targets every time, keeping your QA process tight, efficient, and repeatable.

From Raw to Packaged: Where Color Can Slip

Let’s walk through a typical cashew roasting process. Color issues can pop up at any point.

1. Preparation – You sort and clean kernels, then adjust moisture to 5–7%. Too much water = pale roast; too little = fast browning.
2. Optional Blanching – You steam to remove skins, then dry back to 5%. Inconsistent moisture here skews roast uniformity.
3. Roasting

• Oil roasting at 160–175 °C for 3–5 min. Pull at the exact gold hue—subjective guesses introduce errors.
• Dry roasting at 140–160 °C for 15–30 min. Without continuous color checks, batches run pale or over-roast.

1. Cool & Season – Improper cooling affects final appearance and texture.
2. QC and Packaging – Visual checks and moisture tests help, but they miss subtle color shifts until it’s too late.

That’s where objective color measurement makes the difference.

Transparent plastic preforms are essential for companies that manufacture goods like beverages, edible oils, and intermediate chemicals like alcohols and glycols to form the container for the end product. The color of these preforms is equally vital, helping determine the final product's appearance and its impact on consumers' acceptance, buying decisions, and perceptions of quality.

Beyond influencing your customers, color consistency keeps manufacturing costs under control, since alterations can lead to waste. All cement the importance of color measurement at every stage of production to uphold quality assurance (QA) throughout the supply chain, from raw materials to finished goods.

The Challenges With Color Consistency in Transparent Plastic Preforms

Multiple factors can impact the appearance of transparent plastic preforms, from raw material variations to processing conditions and physical characteristics. All present specific challenges to overcome to achieve consistency and the desired appearance.

Variability in Raw Materials

Variability in raw materials is a frequent challenge for every plastics manufacturer, as well as producers who rely on plastic preforms.

Global regulatory bodies and consumers are embracing sustainability, leading to higher demand for the inclusion of more recycled polyethylene terephthalate (rPET). With this rising expectation comes new challenges, since rPET often contains high amounts of optical brightening agents (OBAs) to overcome yellowing. Every delivery of raw materials typically differs in that composition, making color measurement crucial to managing rPET variations successfully. Quantifying color at this stage empowers scientific, objective, and data-driven decisions to uphold aesthetics, quality, and performance.

Other challenges include variations in the amount and type of additives and pigments that can influence the final color. Additionally, contaminants like dust or residual color from previous runs may lead to alterations in appearance or clarity.

Physical Preform Properties

Transparent plastic preforms naturally present measurement challenges due to their physical properties.

Preform shapes and specifications represent the first difficulty. Contoured surfaces and variations in thickness inherently impact cooling rates, which can lead to alterations in color consistency. Inaccurate sample presentation can further influence measurement accuracy.

Additionally, transparent plastic preforms are susceptible to haze that affects color perception. This cloudy appearance is often caused by microparticles embedded within the plastic, which causes light to scatter when it interacts with the sample.

How Spectrophotometry Addresses the Challenges

Spectrophotometry is the most accurate and objective way to quantify color in transparent plastic preforms. Top-rated spectrophotometers solve the issues of manual visual evaluations — observer fatigue, error-prone assessments, and variabilities in surroundings that can affect how we perceive appearance.

Specialized Design for Transparent, Contoured Surfaces

This equipment provides scientific, numerical color data through specialized optical geometries and controlled lighting by measuring transmittance — the intensity of light at specific wavelengths within the visible spectrum that passes through the sample. Operators can then compare the readouts against established scales and indices, such as the Yellowness Index, to ensure the preform falls within acceptable tolerances, promoting consistent and repeatable results.

Higher rPET Content Without Guesswork

Tight color control with spectrophotometry is also how brands increase rPET without sacrificing appearance. When you have objective color data within seconds, you can raise recycled content while protecting appearance. Capture color measurement during incoming to set OBA dosing from data, not estimates. Using the same approach for in-process assessment and final inspection also helps identify alterations faster to uphold your quality control (QC) and support color consistency, even across different sites and suppliers.

Polyethylene terephthalate (PET) preforms are essential to attractive, durable packaging for industries like beverage manufacturing, edible oils, and more. As the market continues to grow, so does the need to accurately and objectively quantify appearance to uphold product quality. Spectrophotometry is the best solution for scientific color measurement, eliminating the error-prone nature of manual visual assessment for higher confidence and precise data. Explore why color matters in preforms, the challenges of color consistency, and the ideal equipment for measurement to ensure high-quality results.

Why Color Matters for Plastic Preforms

Color plays an instrumental part in conforming to standards, protecting products, and influencing consumers.

Industry Standards

Plastic preform color is vital in meeting industry-specific standards. Sectors like pharmaceuticals and beverages often have strict color tolerances to ensure safety, traceability, and regulatory compliance. For example, specific packaging colors may indicate the presence of certain additives or differentiate between product formulations. Adhering to these color standards helps uphold product integrity and consumer safety.

Product Protection

Some goods, such as certain pharmaceuticals and beverages, are sensitive to ultraviolet (UV) light. Ongoing exposure to UV rays can cause degradation, affecting visual appeal, medical efficacy, safety, or taste. Opaque plastic packaging forms a shield against UV light, helping protect the product within against excess exposure. Inconsistent color may signal uneven distribution of colorants or UV-blocking additives, potentially increasing the chances of UV rays penetrating the packaging.

Quality Perception

Products like edible oils and beverages compete in crowded marketplaces. As a result, standing out on the shelves is key to your success. The plastic colors you choose help attract attention and reinforce your branding with consumers. When your color remains consistent and appealing, it indicates your commitment to quality and meeting your customers' expectations. Conversely, color alterations can signify issues with your quality control or manufacturing processes, causing consumers to reach for a competitor's product instead.

The human eye can perceive millions of colors, but it does not always distinguish them accurately. Two slightly different colors may appear the same, or identical colors may look different depending on viewing angle and lighting. This creates challenges when communicating about color. For designers and manufacturers, the inability to precisely identify and communicate color complicates efforts to replicate standards and detect discrepancies.

To reproduce an exact color consistently, manufacturers and designers rely on ways to quantify a color's properties and calculate the numerical difference between colors. CIELAB, or CIE L*a*b*, is a device-independent, three-dimensional color space that measures and compares all perceptible colors using three values. In this space, numerical differences correspond to the degree of change humans can perceive.

CIELAB is based on opponent color theory showing that the brain interprets retinal inputs as differences between light and dark (lightness) and between opposing pairs of colors: red/green and blue/yellow. This is known as the principle of color opposition correlation, as a color cannot be both red and green, or yellow and blue, simultaneously. For example, you will never see a "greenish red.

What Is the CIELAB Color Model?

The L, a, b color space was first defined in 1942 by Richard S. Hunter, founder of HunterLab. Hunter’s system used coordinates labeled L, a, and b, calculated from the CIE 1931 XYZ color space, and was intended to be more perceptually uniform. In 1976, the International Commission on Illumination (CIE) created the CIELAB model as a refinement of Hunter’s work. To distinguish between the two systems, CIELAB uses L*, a*, b* notation. The “CIE” refers to the French name of the organization: Commission Internationale de l'Éclairage.

Both Hunter L, a, b and CIELAB (L*, a*, b*) are grounded in Opponent-Color Theory, which assumes that the human eye perceives colors in opposing pairs:

• L scale: Light vs. dark, with low numbers (0–50) indicating dark and high numbers (51–100) indicating light.
• a scale: Red vs. green, with positive values indicating red and negative values indicating green.
• b scale: Yellow vs. blue, with positive values indicating yellow and negative values indicating blue.

An ideal color scale would be uniform, meaning that a one-unit difference would appear visually equal regardless of hue. In practice, neither Hunter L, a, b nor CIELAB is perfectly uniform. Hunter’s scale applies a square root function to Y/Yn for calculating lightness (L), which tends to compress values in the yellow region and expand them in the blue region. CIELAB, by contrast, applies a cube root function to X/Xn, Y/Yn, and Z/Zn, with a linear extension near black. While this improves uniformity overall, CIELAB tends to over-expand the yellow region of color space. Both scales are effective for measurement and for setting tolerance standards. However, CIELAB generally provides a closer match to visual perception. With practice, either system supports intuitive understanding and communication of color values.

The color of coconut oil indicates details like freshness, quality, and flavor, influencing whether a consumer chooses a product off the shelf. The essential role that color plays means you need a refined measurement process. Adopt the following best practices to ensure accuracy and support your quality initiatives.

1. Understand the Color

Before measuring spectral data, learn about the factors influencing coconut oil color. This oil ranges from white or light yellow to darker shades like amber. The appearance depends on the type of coconut used, the extraction method, and any impurities or additives present. During storage, other influences, including temperature and lighting, can change the color. 

Knowing how these factors influence appearance — and at what manufacturing stage — gives you the background to proactively address variations by controlling production processes. 

2. Implement the Right Tools and Equipment

A spectrophotometer delivers the most accurate data measurements. It works by shining a controlled light on a sample and analyzing the wavelengths emitted. The device quantifies the light based on an industry-standard color scale or index. 

Outdated methods, such as visual comparison, introduce many inaccuracies. A person's perception could change based on factors like the light source and their level of fatigue. A spectrophotometer eliminates subjectivity to supply more accurate and consistent results. 

Modern consumers have endless opportunities to choose products from your competition. Product consistency matters, and a visual inspection is no longer enough to gauge it. To appeal to the most discerning customers, your products need a precise, uniform appearance — and you need an accurate color measurement tool to ensure that's the case.

The Benefits of Spectrophotometers

Spectrophotometers measure light transmittance or reflectance from plastics, foods, drinks, and other materials. They eliminate the guesswork of visual evaluations and variable observation conditions, such as lighting, that affect the way we see color.

Using a spectrophotometer enhances a brand's identity by associating specific colors with its products. Inconsistent coloring can confuse consumers, leaving them more likely to choose a competitor's option over yours. The more consistent your products are, the more likely a consumer is to stay committed to your brand.