We describe the use of biopolymers, such as sodium alginate, as an sustainable adhesive binder for several metals and high-density polyethylene. A standard pull test and peel test was performed with disks, made of different material and size. Adhesive failure was investigated by varying the amount of applied alginate solution, drying time, drying temperature, effect of surface area, and the nature of the adherend. Alginate adhesion was remarkably strong, relatively general, and sensitive to the presence of water. A brief comparison with other biopolymers is also provided.