In the present study we clarify phase diagrams related to silk fibroin processing into three-dimensional porous structures useful for biomaterials and for scaffolds in tissue engineering. All-aqueous and organic solvent (hexafluoroisopropanol) modes of processing are compared relative to solution concentration of silk protein polymer and size of porogen (NaCl particles). The results clarify the range of conditions under which these biomaterial matrices can be formed, with a broader range of pore sizes and smoother surface morphology generated from the organic solvent process. These structures are directly applicable to fundamental studies of protein-based biomaterial assembly as well as cell interactions and tissue formation with these systems.