piombo UVLead crystal glass, ceramics and glass-ceramics constitute a “punctual” type of contamination for the ready-to-furnace cullet, i.e. they consist of a very limited number of “foreign” fragments dispersed in large quantities of cullet.

Stazione Sperimentale del Vetro has developed a dedicated investigation protocol, which allows to obtain an accurate and reliable quantification of the concentration of these pollutants: the protocol starts with the sampling of a significant amount of furnace ready cullet (tens of kilograms), which is then inspected under different light sources (UV and visible), entirely ground, and is finally chemically analyzed to provide the average content of PbO, and the differentiated contribution deriving from fragments of lead glass and from soda-lime glass cullet.