Provided is a method for the application of a polymer coating to an internal surface of a container, which method comprises: (a) heating the inside surface of the container to be coated; (b) spraying an aqueous suspension of a fluorine-containing polymer onto the surface to form a coating on the surface; and (c) sintering the coating; wherein the container comprises a base and one or more side walls defining a container opening and is suitable for storing a medicament, and wherein the spraying step is conducted with a first spraying means configured to produce an axial spray pattern that is substantially conical about an axis perpendicular to the container base.