The mechanical strength of ices, especially for the glacier has been studied since 19th century. However, there are few industrial applications such as mechanical processing tools without ice-blast. Because the specific data of mechanical properties for ice are unknown. Therefore, we produced four types of ices which had different clearness using aeration system, and measured the hardness of ices from 77 K to 268 K. Furthermore, the indentation displacements were also measured during the hardness test, so that the Elastic Recovery Ratios of ices were investigated in this study.
