What is Masame Hada in Japanese Katana terminology?

Masame Hada or 柾目肌 in Japanese, refers to a type of pattern on the surface of the ground iron (jigane) of a Japanese sword. The term ""Masame Hada"" refers to a pattern that appears as straight lines, resembling the grain of straight-grained wood, specifically the rings of a tree.

This pattern is created during the ""Orimodoshi Tanren"" (折り返し鍛錬), a process of repeated folding and forging. In this process, the ground iron is folded in one direction only, which results in the beautiful Masame Hada.

Masame Hada is most prominently seen in the works of the Yamato tradition's swordsmiths, especially the Hosho school (保昌派). The Yamato tradition is one of the major traditions of Japanese swordsmithing, known for its high-quality swords.

Furthermore, when the Itame Hada (wood grain skin) is mixed with the Masame Hada, it creates a pattern that resembles the flow of a river. This is referred to as ""Masame Nagare"" (柾流れ).

The pattern of the ground iron (jigane) plays a significant role in the aesthetics and value of a Japanese sword. It is one of the factors that sword connoisseurs look at when evaluating a sword. The Masame Hada, with its straight lines resembling the grain of straight-grained wood, is a distinctive feature that sets the sword apart.