How Color Technology Takes the Guesswork Out of Plastic Preform Measurement

Preforms are one of the fastest growing markets in the plastics industry and color technology serves a viable role in monitoring quality and consistency in these products. Preform plastics make up a variety of products used to package beverages, detergents, condiments, and many other packaging materials. Using an injection molding system, these products are stretch blow molded1 and inflated into the various shapes necessary for product development. Color technology enables manufacturers to monitor the color of raw plastic materials and predict final color outcome based on spectral data and analysis. Based on transparency and reflectance values, different color technology measurement systems are required to ensure product quality and consistency.

blue plastic bottles color technology
Color monitoring and control in plastic materials ensures final product color consistency and acceptability.
Image Source: Flickr user Reciclado Creativo 

Measuring Variations in Transparency

Preform plastics come in a multitude of sizes, shapes and colors, ranging from opaque to translucent or transparent. Variations in these materials require different measurement techniques to monitor color quality and consistency depending on the sample type.

Opaque Preforms: These materials are impenetrable to light and can be defined by the lack of transparency or visibly of light through the sample. Instrumentation that measures reflectance value is recommended for monitoring opaque samples for color quality and consistency.

Translucent Preforms: Light is diffused as it passes through these sample materials causing altered visibility through the sample material. Color technology that utilizes both reflective and transmittance measurement modes is recommended for translucent sample types.

Transparent Preforms: Light passes through these materials with little or no distortion so that objects on the other side can be clearly seen. These preforms can only be measured using transmission instrumentation to monitor haze and visual clarity.

clear bottle brown liquid color technology
Haze measurement is an important part of color technology that monitors the transparency of plastic materials to enhance product visibility.
Image Source: Flickr user Alexander Bolotnov

Spectrophotometers are able to account for the many variations in plastic materials and color technology can be adapted accordingly to quantify the color and visibility of these products. Spectral technology is able to measure the path of light as it is seen by the human eye, accounting for variations in sample thickness and texture.

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Haze Measurement in Clear Plastics

Many plastic preforms utilize transparent or clear plastic materials to promote product visibility. Yellowness, whiteness, or haze can alter the visibility of transparent plastic materials and require the use of specific geometries and measurement modes to ensure clarity. Color process monitoring of preform plastics can be used to determine the amount of haze and degree of color in the preform or container sidewall. Spectrophotometers rapidly quantify this information allowing for real-time monitor process changes to occur. This technology can alert production changes before final batch inspection, saving both time and resources while ensuring product quality and visibility.

clear plastic container color technology
Clear plastics vary in transmission and haze measurement and must be carefully monitored to maintain product visibility.
Image Source: Flickr ilovebutter

Color Technology Tools

Quality instrumentation is essential for monitoring preform color and ”can be used to verify lot-to-lot- consistency, predict final blown bottle color from the preform color and get into target range when switching over a line to a new color.”2 At HunterLab, we specialize in color measurement instrumentation and have extensive experience in plastic color measurement. As preform plastic manufacturing grows steadily, HunterLab continues to develop instrumentation that best serves the quality and productive needs of this industry. For more information on color technology and instrumentation for preform plastics, please contact Hunterlab today.

  1. “Overview: Stretch Blow Molding,”
  2. “How to Measure Plastic Preforms,”

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