The preparation of fine powders by grinding may be accomplished either by wet or dry processes, the differences between these have been discussed. It is well known that there are many mechanical properties which have direct effects upon the grindabilities of solids, breaking properties in particular. In addition, the difference of breaking strength in different atmospheres is also known. In this study, dynamic bending tests were carried out, using a drop weight method, on glass, to assess the quantitative effect of a water atmosphere on fracture probability. The influence of the crack length on the glass surface and repeated impact on the difference of fracture probability in water and in air was also studied. As a result, it was found that the fracture probability in water was larger than that in air when the crack length of the glass surface and the input energy to the specimen were constant. The above difference increased with decreasing crack length and input energy to the specimen. It was confirmed that a wet grinding process is useful from the point of view of fracture energy. (C) 2004 Elsevier Ltd. All rights reserved.