3M Microbial Material Matter - Evaluating Growth, Colouration, and Coating Methods for Bacterial Cellulose

This study investigates bacterial cellulose (BC) as a sustainable biomaterial for design applications, focusing on how natural pigmentation and coatings influence its aesthetic and functional performance. The research aims to push the boundaries of material development and enhance design applicability by combining domestic-scale fermentation techniques with organic additives, pigment integration, and post-growth treatments. Central to the investigation is a year-long assessment of BC’s durability, colour stability, and overall behaviour under real indoor conditions - marking a departure from conventional studies that evaluate biomaterials at a presumed state of readiness. This extended, time-dependent approach provides valuable insight into how BC changes over time, informing sustainable design practices and material innovation. BC sheets were coloured in-situ using natural pigments - including beetroot, hibiscus, saffron, red cabbage, coffee, curry, and food dyes - and treated ex-situ with coatings such as wax, beeswax, and coconut oil. The material was then incorporated into functional design prototypes such as vests, bags, lampshades, chandeliers, wall panels, and chairs, and observed over one year in indoor environments with 20–30% humidity and variable sunlight exposure. Beetroot and hibiscus proved the most effective in promoting growth and colour longevity. Beetroot accelerated growth due to its sugar content, while hibiscus maintained vibrant tones without disrupting microbial balance. In contrast, curry, coffee, and henna compromised structural integrity. Coatings preserved flexibility short-term but led to brittleness over time. Overall, in-situ pigmentation outperformed post-processing techniques, with the study highlighting both the material’s evolving nature and the challenges of stabilising bio-based materials for design.