Solarization-resistant glass composition having a UV-cutoff with a definite transmittance gradient and radiating device for a weathering apparatus containing a glass of said composition

2232322222232233232 3 2 23 The borosilicate glass with improved solarization-resistance has a transmittance curve within an area bounded by respective curves defined by the corresponding equations τ=1.7·(λ−277) and τ=1.6·(λ−284) in a wavelength range of 283 nm to 325 nm. This glass has a composition, in wt. % based on oxide content, of: 55-82, SiO; 10-20, BO; 1-10, AlO; 0-5, LiO; 0-10, NaO; 0-10, KO; 0-10, ΣMO; 0-5, MgO; 0-10, CaO; 0-5, SrO; 0-15, BaO; 0-15, ΣMO; 0-3, ZrO; 0-5, ZnO; 0-2, CeO; 0-3, WO; 0-2, SnO: 0-0.1, FeO; 0.05-2, MoO; 0-5, BiO; 0-1, TiOand 0-5, oxides of selected rare earth and Group IVB to VIIIB elements. The transmittance is adjusted by varying the MoOcontent and if necessary the TiOand BiOcontent. The glass is especially suitable for use in a weathering apparatus.