Tempered glass for thermal insulation

The invention relates to glass which has undergone chemical tempering such as to have an alkaline ion concentration gradient from the surface thereof over an exchange depth of at least 100 m, a surface stress of at least 200 MPa and a core viscosity point of at least 550 DEG C. The inventive glass can be used, for example, in the field of domestic cooking as a pyrolytic oven door, frying pan, range, fireguard, chimney insert and, more generally, in order to separate two gaseous atmospheres at different temperatures. The glass is particularly resistant to thermal shocks.