The effect of water soaking and heat-treatment in saturated water vapour at
250°C for 192 h on the strength of silica glass is studied. Bending strength
meaurements in liquid nitrogen showed a clear increase of the inert strength
for heat-treated specimens over that of the untreated material. The increase
in strength is interpreted as the consequence of water diffusion into exposed
surfaces of the test specimen, which results in swelling of the glass and
shielding of cracks, present in the surface of the glass. Experimental results
are compared with theoretical predictions
