Abstract
The Kusare, which iron foundrymen in our country call, has a dendritic fracture and is dark brown or violet. Some investigators say that the Kusare is an internal shrinkage hole caused by solidification of molten iron. However, it is concluded by my experiments that the Kusare is not the internal shrinkage, but the external shrinkage hole The results obtained are as follows: 1. It is impossible to discuss the Kusare on casting designs or gases of molten iron. 2. When the gas pressure of the core is over the vapour pressure of molten iron, the Kusare is formed. 3. The Kusare is not the internal shrinkage hole, but the external one caused by gases evolved from molds and cores.
