The value of recyclable plastics is determined by their size, resin composition, and color.

For example, clear and white plastics are understandably preferred for recycling, as they are easier to process. This is because they can be dyed with greater flexibility. On the other hand, dyed and pigmented plastics can pose challenges for materials recovery facilities (MRFs). For instance, a red plastic container can only be dyed to black or colors with much darker shades, resulting in reduced recycling value. Some recycling facilities may even opt to dispose of these pigmented plastics, as they can contaminate and complicate the recycling process for other batches.

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Black Plastics:

Manufacturers aiming to ensure the proper recycling of their post-consumer packaging should take into account the pigmentation and translucence of their bottles and containers. Even a PET container may be rejected by certain recycling facilities if it is colored and/or opaque. Currently, three types of pigments are predominantly used to color plastic packaging. Among these, carbon black is the most commonly used pigment for black packaging materials due to its cost-effectiveness and strong coloration. However, it does not reflect infrared radiation, making items manufactured with it nearly invisible in sorting plants. As a result, significant quantities of plastic packaging cannot be sent for recycling.

In automated recycling facilities, near-infrared detection (NIR spectroscopy) is employed to rapidly sort plastic waste into different types. In most cases, infrared cameras are positioned above conveyor belts for this purpose. Nevertheless, the optical sensors struggle to correctly identify black plastic packaging, such as foils, due to its color, and, as a result, it cannot be effectively sorted.