Use of fumed alumina in fluorescent lamps can significantly improve the performance and service life of lamps.  Fumed alumina is an ideal choice for this application as it is transparent in the visible light spectrum, has high ultraviolet light reflectance and chemical stability at high temperatures.

SpectrAl^® fumed aluminas are used in three components of fluorescent lamps:

• In the barrier layer, a coating on glass tube, fumed alumina prevents migration of sodium into the phosphor during production of lamps and prevents migration of mercury into the glass tube during usage.  By preventing migration of mercury into the glass which causes graying and reduces efficiency, fumed alumina increases service life of fluorescent lamps.
• The reflector layer functions to reflect back into the phosphor any UV light not initially captured thereby maximizing the effectiveness of the phosphor.  Fumed alumina which has high UV light reflectance and good visible light transmittance enhances the performance of the lamp.
• In the phospor layer, the positive surface charge of fumed alumina acts to bind the phosphor particles together and to the glass substrate which are both negatively charged.

SpectrAl 100 fumed alumina which has the highest surface area and smallest particle size offers the best adherence to both phosphor and substrate.  In all components of fluorescent lamps, SpectrAl 81 with a lower surface area may offer some advantages in intoducing less adsorbed gases and water into the lamp.