Elimination of Swirling in PET Food Packaging

I’m Wilfried Grob, part of the Penn Color sales team in Europe. At Penn Color, we strive to continuously improve by offering best-in-class customer experiences and tailored solutions that help optimize our customers’ processes. One of our largest consumer packaging customers operates across multiple production facilities, with lines that vary significantly in age, size, and degree of automation. Despite these differences, the same colors and masterbatches are often used across all sites. Over time, the customer began to notice intermittent color variations. These were not constant but appeared unpredictably in certain runs and on specific machines. The issue was traced to an inhomogeneous distribution of colorant, resulting in visible “swirling,” which increase non-quality output and production downtime.

To address the problem, Penn Color’s technical team in Venray, The Netherlands, set out to better understand and replicate the effect. The color lab developed an internal test method that helps correlate swirling with specific process conditions. Using this method, the team created on a “swirling risk” map for color chips, which provided a reliable framework to run controlled experiments.

Systematic testing revealed that the process was significantly more sensitive and prone to swirling, depending on the balance between pigment and carrier material. The team discovered that small formulation adjustments could either exacerbate or significantly reduce the effect. After producing and evaluating many color chips, the optimal combinations were defined, leading to the development of new drop-in masterbatches with a much wider operating window, ensuring production remains within quality specifications, despite the inherent variability of the manufacturing process

The new formulations delivered impressive improvements in robustness and color consistency across the customer’s various production lines—new and old, large and small, highly automated and fully manual. Thanks to this collaborative effort, the customer now benefits from more reliable production with reduced waste and variability across multiple pieces of equipment and sites. By combining systematic lab work with a deep understanding of the customer’s processes, Penn Color delivered a tailored solution that ensures reduced total costs to produce and peace of mind!