Ion exchange in silicate glasses is becoming a widely used process for both glass strengthening and modifications of near surface refractive index. Process configurations can be purely thermal or may be assisted by an external electric field. Ion sources can be molten salts reservoir or thick film deposited on the glass surface. In process analysis or process predictions, the classical diffusion solutions are generally considered: erfc-like in case of wide ions reservoir or Gaussian-like in case of thick surface layers sources. These solutions may be considered, in some way, "conventional" because they are often proposed in spite of the implicit approximations included in the assumptions of the boundary conditions (instantaneous constant equilibrium concentration attained at glass surface and constant initial concentration) under which they are derived.
