Water diffusion in silicate glasses under natural weathering conditions: evidence from buried medieval stained glasses

In this study, ion-microprobe analyses of four samples of buried medieval stained-glasses are used to demonstrate that water penetrates into the matrix of pristine glasses at low temperatures, thereby showing that glass alteration is not only a surface process. The diffusion coefficients of water determined from concentration profiles of hydrogen are found to be correlated with the bulk polymerization state of the glass. This observation is discussed with respect to glass structure and implies that ionic exchange between hydrogen and network modifying metal cations is the major process responsible for glass hydration.