The “Green” Knight in Silver Armor: Using Label Color and Package Shape to Overcome the Weakness Bias Against Eco‐Friendly Detergent

ABSTRACT This research examines the role of packaging design in shaping consumer perceptions of eco‐friendly laundry detergents, with a focus on addressing the common “weakness bias” that can undermine the appeal of sustainable products. As consumers increasingly prioritize purchases that reflect their social and environmental values, it becomes essential for brands to ensure that eco‐friendly offerings are perceived not only as ethical but also as effective. Our study investigates how key sensory packaging elements—specifically label color and package shape—can be leveraged to enhance perceived strength without compromising the product's eco‐friendly positioning. Drawing on sensation transference and associative network theories, we hypothesize that a silver eco‐friendly label, compared to the more traditional green label, signals greater strength (meaning the product is more effective at its designated task, i.e., cleaning laundry) and efficacy, especially when applied to an angular package design. Across two lab experiments and one field study, we demonstrate that silver labeling significantly improves perceived product strength by an average of 0.67 on a 5‐point Likert scale ( p < 0.001) and increases purchase likelihood by an average of 0.47 on a 5‐point Likert scale ( p < 0.001), with these effects further amplified when combined with angular packaging. These findings offer important insights for nonprofit organizations and social enterprises, which often face unique challenges in balancing sustainability goals with perceived product efficacy, to strengthen the marketability of eco‐conscious products. While relevant for all companies, this approach is particularly crucial for these entities due to their reliance on consumer trust and mission‐driven branding. By adopting packaging strategies that communicate both environmental responsibility and product effectiveness, brands can better align consumer behavior with their philanthropic and sustainability goals. This research provides practical recommendations for enhancing the perceived value and impact of sustainable products, ultimately driving greater support for environmentally conscious consumption.