An important aspect of Siemens research is the best result of electrolytic polishing of niobium by operating under high current oscillations. A brief description of the causes of current instability is as follows: The electrolyte mixture contains sulfuric acid (H2SO4) and hydrofluoric acid. Sulfuric acid acts as an oxidant to form niobium pentoxide (Nb2O5), an electrical insulator. hydrofluoric acid dissociates niobium pentoxide. Under the influence of potential, both processes occur at the same time and occur at a fairly high rate. As the electrolytic polishing proceeds, a dielectric layer of niobium is formed at the surface of the niobium (anode). hydrofluoric acid diffusion from the electrolyte takes time through the dielectric layer and produces a sufficiently high concentration to crush the Nb2O5 layer, allowing the current to reach its maximum. The hydrofluoric acid concentration is then partially depleted and the current is minimized until sufficient time has elapsed to allow diffusion to establish an hydrofluoric acid concentration on the surface of the niobium pentoxide. The electrochemical cycle is then infinitely repeated as long as the bulk electrolyte solution can supply the desired amount of hydrofluoric acid.

Researchers at Siemens reported for the first time an intermittent diffusion-limited electrolytic polishing of niobium for superconducting radiofrequency (SRF) cavities. Using the principle of Siemens development, continuous electrolytic polishing of the rotating niobium cavity is described by researchers at KEK and Nomura Plating, which is a particularly valuable source of the history of SRF cavity electrolytic polishing.