Properties of metallic films in precise calculation of the Casimir force
  Optical properties of the deposited gold films are discussed in connection with the Casimir force prediction. Voids in the films and electron scattering on the grain boundaries reduce the force at small separations on the 2% level in comparison with the bulk material prediction. The contribution of the patch potential due to polycrystalline structure of the films is shown to be small for the existing Casimir force experiments. 
V. B. Svetovoy