Decreasing lead exposure from lead crystal by sol-gel coating

Abstract

Investigations to develop sol-gel coatings on lead crystal glasses were carried out to reduce the migration of lead into beverages. Therefore three compositions (SiO2, Na2O/B2O3/SiO2 and B2O3/SiO2) were tested as coating materials. The best result was obtained from the B2O3/SiO2 system. The coatings were densified to clear, transparent layers about 0.2 µm thick, not influencing the appearance of the lead crystal glass surface. For the coating of the inner walls of lead crystal containers, a special process has been developed. The coating reduces the leaching of lead to some percent of the value of uncoated surfaces and does not lose its effectiveness after 20 cycles in a heavy duty laboratory dishwasher.