Biobased coatings for architectural timber applied using the robotic 3D printing technique

Materials applied for coating architectural timber are often environmentally harmful. This study examines a sustainable alternative—a coating from microfibrillated cellulose hydrogel applied for the first time on architectural timber using robotic 3D printing. The proposed solution is evaluated through architectural design and robotic 3D printing experiments, with patterned coating designs deposed onto eight architectural mockups. Through qualitative and quantitative analyses of coating features preproduction and postproduction, fundamental aspects affecting coating design are identified, namely, the 3D printing path geometry and layout, substrate type, and precoating material. These aspects are correlated with the final architectural coating qualities at the mesoscale and macroscale by characterizing dimensional stability, geometric features, and color appearance. The best coating effects are observed for pine substrates precoated with hydroxyethyl cellulose. By delivering new knowledge on biobased architectural coatings, this study contributes to the global effort of phasing out fossil-based materials in the built environment.