The initial stage of alkali silicate glass corrosion is studied using spectroscopic ellipsometry and secondary ion mass spectrometry. These techniques reveal the presence of at least two layers: a first layer, very thin, with a low refractive index, formed at the glass surface and an underlying second layer, thicker and denser. The second layer is not entirely depleted in sodium. The layer thicknesses respectively obtained from SE and SIMS are in good agreement. A pre-corroded layer of about 600nm is always observed at the glass surface. The composition modification of the solution with leaching time is followed by chemical analysis of the solution. This technique provides a higher amount of sodium in solution than expected. In addition, SE leads to an apparently surprising result: layers tend to become denser with leaching time.
