Abstract: A low-pressure mercury vapor discharge lamp is provided with a light-transmitting discharge vessel (10), enclosing, in a gastight manner, a discharge space (11) provided with a filling of mercury and a rare gas. The discharge vessel (10) comprises means (41A) for maintaining a discharge in the discharge space (11). At least a portion of an inner wall of the discharge vessel (10) is provided with a translucent layer (16), which according to the invention has a thickness in the range from 1 to 50 (m and comprises an alkaline earth borate. Starting materials for the translucent layer (16) are nano-particles of calcium strontium, and/or barium borate, enabling the production of such thick translucent layers. Preferably, the discharge vessel (10) is made from a sodium-rich or a soda lime glass with a glass composition comprising the following essential constituents: 60 to 80% SiO2 and 10 to 20% Na2O by weight.