It is shown that the active material obtained in the use of Victawet as a parting layer for electron microscope replicas is the inorganic decomposition product sodium metaphosphate (S.M.P.). The results of an investigation of the parting layer characteristics of S.M.P. suggest its use in applications which have previously employed Victawet. Measurements with radioactive tracers indicate that on smooth surfaces reproducible stripping can be realized with parting layers of S.M.P. a few molecular dimensions in thickness. The use of a ribbon filament source with this material is recommended to minimize shadowing effects and thus reduce the thickness of S.M.P. required for successful stripping.