During the grinding of glass, a damaged layer is formed at the surface. The damaged layer has a layer of relief, the depth of which corresponds to the maximal roughness criteria, R(max) and a layer of cracks the depth of which is approximately three times larger than the depth of the relief This damaged layer has a deleterious effect on glass properties in particular mechanical strength. The influence of the surface state damaged by grinding with fractions of three different grain size on the biaxial bending strength of soda-lime-silica flat glass is studied.