Natural and simulated aging of historical glasses

We thoroughly studied coloured glass tesserae of historical glass windows of the Santi Giovanni e Paolo Church in Venice by means of ESEM and XPS techniques in order to evaluate the weathering mechanisms of the glass surfaces. The results show a strong impoverishment of the relative content of alkaline ions on the surfaces. Moreover, we exposed the freshly broken surfaces of the samples (having the original glass composition) to an accelerated light and wet/dry aging process using the current rain composition of Venice and then compared to the natural aged surfaces. The results show the validity of the artificial aging methodology employed that allows the measurements of the different leaching rates of the samples.