Soiling of silica-soda-lime float glass in urban environment: measurements and modelling

Modern silica-soda-lime float glass samples were exposed to background pollution conditions in Paris, sheltered from rain, during 1, 2, 6, 12 and 24 months. Analytical scanning electron microscopy pointed to the importance of soot particles and soluble salts as fine and coarse deposited particles. Four pertinent soiling parameters were measured: total mass of deposited particles (by weighing), mass of total carbon (by thermo-coulometry), mass of water soluble ions (by ion chromatography on glass surface rinsing water) and haze (by spectrophotometry). Model fitting to experimental data showed a continuous increase of soiling in time, following a variable slope sigmoid (Hill equation) for all the four soiling parameters. This similar evolution allowed defining one general model for soiling.