The Complete Guide to Measuring Opaque Plastic Preforms

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.

Spectrophotometry's Role in Color Quality

Plastics manufacturing and processing are uniquely challenging, with multiple factors impacting lot-to-lot consistency and accurate data capture.

Expose Process-Related Issues

Preform color must be consistent for the best appearance and maximum product protection against UV rays. Opaque plastic preforms naturally contain more pigment than translucent or transparent ones, and detecting when color is off could expose issues with pigment concentration or distribution.

Moisture in plastic preforms can also lead to appearance inconsistencies and undesirable visual effects in packaging products. Spectrophotometric measurements can help detect even subtle color alterations, which may indicate improper moisture control methods or drying agent use at the supplier facility.

Viscosity — the plastic's resistance to flow — affects how well colorants disperse throughout the preform. Inconsistencies in viscosity can lead to issues like streaking and uneven colorant distribution, causing deviations in resin batches or revealing issues with molding processes.

While color measurement alone cannot diagnose specific process-related issues, it is essential in revealing where shifts may occur. Manufacturers can use the resulting data to better assess supplier performance and quickly make any necessary vendor changes to ensure future quality.

Uphold Quality Assurance in Incoming Raw Materials

Color consistency in the final packaging starts at the preform, which starts with the color in the plastic resin or pellets used to create the preforms. The increasing demand for recycled PET (rPET) introduces new challenges — every incoming shipment will likely have a different color composition depending on the type and amount of rPET included. Color measurement is crucial to managing these variations successfully during incoming quality assurance (QA), as it empowers data-driven decisions to uphold your quality standards.

Measure Appearance Accurately Despite Unique Sample Shapes

Opaque plastic preforms have a distinct shape challenge as well. Curved surfaces, textural differences, and varying thickness can create inconsistencies in light reflection and impact results. Spectrophotometers are engineered to overcome these issues through measurement approaches and methodologies that can compensate for the physical characteristics natural to preforms.

UltraScan VIS: The Ultimate Solution for Opaque Plastic Preform Color Measurement

HunterLab's UltraScan VIS is the ideal solution for quantifying color in opaque plastic preforms.

Specialized Design and Accessories

We've developed our UltraScan VIS specifically to meet color measurement challenges in modern plastics manufacturing. This device offers diffuse d/8° reflectance measurement and the recommended D65/10° illuminant/observer configuration for better correlation with human visual assessment in natural sunlight conditions. Both large- and small-area view modes are available, simplifying sample averaging. Plus, it's a benchtop spectrophotometer built to deliver fast, easy operation and designed to withstand rugged manufacturing environments.

The unique shape of opaque plastic preforms presents no issue for the UltraScan VIS. An available adjustable reflectance preform holder helps standardize sample presentation for accuracy and consistency.

Incredible Versatility

UltraScan VIS measures the intensity of light at wavelengths across the entire visible spectrum, from 360 to 780 nanometers — ideal for opaque plastic preforms of every color. This spectrophotometer also has the recommended color scales, CIE L*a*b* and CIE L*C*h*, built in, enabling data sharing in widely accepted color languages. Plus, this equipment can capture reflectance in specular included (RSIN) and specular excluded (RSEX) modes.

HunterLab has engineered the top-rated UltraScan VIS to quantify both regular transmission (RTRAN) and total transmission (TTRAN), so it's also perfect for manufacturers working with translucent and transparent plastic preforms.

Support for Sustainability Goals

Environmental, Social, and Governance (ESG) initiatives are priorities for many modern businesses. At HunterLab, we're passionate about helping support your sustainability goals and a more circular economy. Our world-class spectrophotometers empower:

• Waste reduction: Regular color measurement at every stage of manufacturing enables faster detection of color anomalies and inconsistencies that can affect your product's final appearance. Those insights allow you to alter processes sooner to prevent needless waste.
• Energy savings: Ensuring color quality and consistency reduces the need for rework, lessening energy consumption.
• Resource optimization: Repeatability is easier with accurate color data, even with variations in raw material composition. You can quickly identify the color makeup of samples to understand where adjustments may be necessary, optimizing your resources.
• Regulatory compliance: Color measurement helps manufacturers meet legal obligations for post-consumer recycled (PCR) content without sacrificing desirable appearance.

Improve Plastic Preform Color Measurement With a Proven Leader

As the originator of measuring color for appearance, HunterLab manufactures the world's best spectrophotometers. We draw on over 70 years of deep industry expertise to provide top-rated color measurement solutions for leading brands worldwide. Each device we offer undergoes extensive quality testing and includes our legendary customer service and technical support.

Request a quote on the UltraScan VIS today, or connect with our experts for buying advice tailored to your unique needs.