The self-healing behavior of radial cracks generated by Vickers indentation in float glass is analyzed when heat treated at 620 degrees C under various atmospheres. Results evidence that two main driving forces influence radial crack evolution: release of residual stresses induced by initial indentation and capillary forces due to surface energy minimization. Depending on the viscosity level, viscous flow allows crack morphological changes driven by capillarity forces or not. Our results evidence that at 620 degrees C, the viscosity of the glass surrounding cracks can be significantly reduced by water diffusion and glass hydrolysis, or increased by glass des-hydration, as a function of the humidity level of the furnace atmosphere. Hydration and des-hydration of glass are shown to play a major role in the crack morphology changes during healing, respectively, favoring or impeding morphological changes driven by capillarity forces.