Acid Etching removes a thin layer of glass from the surface, and results in a frosted finish. Acid Etching is forever. If it ever needs to be changed, glass replacement is the only option. Stimulated Etching and Acid Etching both give the appearance of a frosted glass but Stimulated Etching is removable. Whether you choose the Acid Etching or Stimulated Etching process, either product will be installed on-site without removing any installed glass.