How Colour Technology Takes the Guesswork Out of Plastic Preform Measurement

Preforms are one of the fastest growing markets in the plastics industry and colour 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. Colour technology enables manufacturers to monitor the colour of raw plastic materials and predict final colour outcome based on spectral data and analysis. Based on transparency and reflectance values, different colour technology measurement systems are required to ensure product quality and consistency.

Colour monitoring and control in plastic materials ensures final product colour consistency and acceptability.

Image Source: Flickr user Reciclado Creativo

Measuring Variations in Transparency

Preform plastics come in a multitude of sizes, shapes and colours, ranging from opaque to translucent or transparent. Variations in these materials require different measurement techniques to monitor colour 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 colour quality and consistency.

Translucent Preforms: Light is diffused as it passes through these sample materials causing altered visibility through the sample material. Colour 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.

Haze measurement is an important part of colour 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 colour technology can be adapted accordingly to quantify the colour 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.

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. Colour process monitoring of preform plastics can be used to determine the amount of haze and degree of colour 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 plastics vary in transmission and haze measurement and must be carefully monitored to maintain product visibility.

Image Source: Flickr ilovebutter

Colour Technology Tools

Quality instrumentation is essential for monitoring preform colour and ”can be used to verify lot-to-lot- consistency, predict final blown bottle colour from the preform colour and get into target range when switching over a line to a new colour.”2 At HunterLab, we specialize in colour measurement instrumentation and have extensive experience in plastic colour 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 colour technology and instrumentation for preform plastics, please contact Hunterlab today.