Fast, Easy, Effective: Utilizing Spectrophotometers to Measure Color Pigment Content in Plastics

Plastics come in a wide array of colors and must undergo various steps of processing to achieve desired results. Measuring color pigment throughout each processing phase is important for maintaining consistency and avoiding product rejection due to color discrepancy. Spectrophotometers allow for the continual monitoring and analysis of color pigments to ensure consistency throughout the supply chain, reducing errors and wasted materials.

measure color pigment
Plastic products come in a variety of colors. However, final product color is determined long before these final stages of production.
Image Source: Flickr user oatsy40

Adding Color to Raw Materials

There are various methods for adding color to plastic products, all involved in the early stages of production. These techniques (described below) rely on different methods of color pigment analysis which utilize spectral technology to achieve desired results.

  1. “Masterbatch” Method: chemically altered, high pigment content pellets are mixed together with naturally colored pellets to achieve desired results.
  2. Pigment Additives: naturally-colored pellets are mixed together with raw pigments to create colored pellets, which are then used to product color specific plastic products.
  3. Pigment/Solvent Method: pigments are first dissolved in a solvent and then sprayed on naturally colored pellets to alter final product color.
  4. Real-time Color Additives: pigments and natural pellets are molded together simultaneously to develop final color specifications.
powdered measure color pigment
Colored pigment is often added to naturally colored plastic pellets to alter final color results.
Image Source: Flickr user tiffany terry

Whichever method is used to alter the color of the plastic product, each one will undergo various changes throughout processing. Continual monitoring of color pigment, dissolved pigment, natural raw plastic materials, and final product color is needed to provide valuable data that can alert production changes and guarantee desired results.

Color Pigment Analysis

Plastic pellet color is most often analyzed before the pellets are extruded or molded into final products. Color pigment measurement is an important step towards ensuring that these raw materials will produce the desired color results. Spectrophotometers offer a quick and simple method of color pigment analysis that can be quantified and repeated to help maintain consistency and quality.

These materials often exhibit differences in shape, texture, and transparency. Therefore, color measurement instrumentation must be designed to measure a variety of sample attributes. From powdered color pigment to dissolved liquid samples to plastic pellet materials that vary in transparency, spectrophotometers rely on advanced geometric principles to accurately quantify color and develop the data need to reproduce these color effectively. Advanced spectrophotometers allow for rapid, in-line color process monitoring to continually monitor color changes and provide valuable feedback for processing adjustments and changes.

plastic pellets measure color pigment
Plastic pellets range in color, shape, and texture which requires advanced measurement instrumentation to effective quantify color and change.
Image Source: Flickr user NOAA Marine Debris Program

Monitoring Inconsistencies

Spectral data and feedback is highly utilized for its ability to monitor inconsistencies both during production as well as in final product appearance. Spectrophotometers can be used to set color standards at various checkpoints throughout production by assigning numerical values and establishing color tolerances. These quality standards1 ensure that products pass final inspections, increase final batch quantities and company profits. Integrating color pigment monitoring with advanced color evaluation instrumentation, creates a system of precise color comparisons that match human eye perception. Using these methods to compare products to manufacturer standards throughout processing will eliminate inconsistencies early on and positively affect final product color.

Need to Measure Color Pigment? Trust Advanced Spectral Technologies

Spectrophotometers are designed to view color in the same way as it is seen by the human eye.2 Advanced instrumentation utilizes non-contact and height sensing technology so that color data is not distorted by interference from outside sources. This assures that final products will meet consumer expectations for quality and consistency every time.

At HunterLab, we specialize in advanced spectrophotometric instrumentation and offer a variety of tools designed to meet the various needs of color pigment analysis in the plastic industry. For more information on the use of spectral technology in plastic color and pigment evaluation, please contact HunterLab today.

  1. http://www.astm.org/Standards/E2539.htm
  2. http://www.colormatters.com/color-and-vision/how-the-eye-sees-color

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