A method for making a magnetic disk, without chemical mechanical polishing to remove asperities, includes the steps of placing an annular-shaped element in a vacuum chamber, exposing a surface of the element to a beam of gas clusters while it is in the vacuum chamber, and thereafter applying a magnetic coating. The annular-shaped element may be a substrate, or it may be a substrate with a base coating such as glassy carbon or amorphous carbon. The substrate may be made of glass, preferably high quality fusion glass. The surface of the annular element may be textured by forming a sequence of concentric annular valleys, with plateaus being left between the valleys, before the magnetic coating is applied. A semiconductor wafer may also be smoothed by a beam of gas clusters to prepare the wafer for photolithography.