Injection Molding Surface Finishes: Comprehensive Guide What are Injection Molding Surface Finishes? Injection molding surface finishes are created by applying specific textures or patterns to the mold’s exterior, which are then applied to its molded parts. From highly polished, mirror-like finishes to rough, matte textures, there are a wide range of available finishes. The Society of Plastics Industry (SPI) categorizes these finishes into several grades, such as A…