Changes to European regulations (REACh, materials in contact with foodstuffs, etc.) to meet the requirements of today’s society may well have far-reaching consequences for a major part of glass industry. It has become essential to demonstrate the ability of glass to retain potentially hazardous elements. A major comprehensive study of a wide range of commercial glass compositions has been pursued to describe the release mechanisms of various glass elements. Five types of silicate glass have been investigated: lead crystal glass (fine glassware), soda lime glass (containers for food and cosmetic industries), borosilicate glass (cooking dishes), barium glass (tableware) and opal crystallized glass (tableware).
Glass alteration was carried out for three years in acetic acid (4 % vol) at pH 2.4 at 70°C. The confrontation of results allowed establishing a referential for the alteration of commercial glasses in acidic medium and unfolding the links between chemical composition, structure and leaching behavior of various elements. The impact of chromium added as a colorant in lead crystal glass has been investigated, pointing out major changes due to structural modifications. Increasing Cr concentrations demonstrated a dual benefit effect on lead crystal chemical durability by reducing the leaching of Pb and increasing the polymerization of the silicate network.
Different types of surface treatments, from chemical reactions to sputtering deposits, have been evaluated. Five surface treatments were tested, all developed by glass manufacturers to address specific needs of their production such as resistance to mechanical abrasion (SnO2, TiO2), esthetics (TiO2, acid polishing), surface tension modification (SiO2) or Pb leaching reduction (SO2 dealkalization treatment). The unique data collected gives access to quantitative information on glass and coating constituents leached in solution over time. Significant reduction of long-term lead leaching, especially in the case of SO2 dealkalized lead crystal glass, is obtained as well as beneficial effects towards the retention of Ba in Ba-containing glass but shows poor interest for borosilicate glass.
The high resistance to significant alteration conditions can be underlined and their endless recyclability make glass highly suitable candidates for sustainable product consumption and packaging.