Chemical Durability Of Lead Crystal Glass: Comparison Of Short-Term Aqueous And Atmospheric Alteration At 90 Degrees C

Crystal glass alteration in an aqueous medium has been extensively studied following the implementation of strict regulations regarding lead leaching. However, despite the widespread use of lead glasses and crystal glass by artists and artisans ever since antiquity, few works focus on crystal glass corrosion in atmospheric conditions. In this preliminary study, the altered layers formed on crystal glass in aqueous and atmospheric conditions at 90 degrees C are compared. On the timescale studied (20 days), ToF-SIMS profiles of both altered layers show water ingress. This hydration step is correlated with K leaching in aqueous media, and(29)Si and(27)Al NMR analysis of the altered structure highlights the formation of newQ(4)and AlO(6)units. Low alkali leaching is observed in atmospheric conditions, but the altered glass structure is highly hydrolyzed, as attested by its high water and silanol content. As a result, the altered layer formed in aqueous conditions is more polymerized than the one formed in atmospheric conditions, and potentially more passivating through a mechanism involving water availability. On the bases of(29)Si/H-1 and(27)Al/H-1 CP-MAS NMR experiments, the oxygen repartition is described in the altered glasses, differentiating the oxygen atoms involved in structural NBO from that of hydroxyl groups.