![katana blade katana blade](https://cdn.instructables.com/ORIG/FV5/IKWW/JCKUEFWS/FV5IKWWJCKUEFWS.jpg)
This is known as fukure and should it break during the sharpening process it is known as fukure-yabure or the “tearing of the fukure“. It may swell in the area to the size of a small bean.
![katana blade katana blade](https://fws-shared.s3.amazonaws.com/uploads/website/auctions/items/full/3162342_05.jpg)
Fukureĭuring the tempering process, should the welding of the metal layers be insufficient, bubbles can occur within the blade. In Hankei swords, they are considered common traits of those swords and not flaws at all. For straight-grain swords or strong swords with a straight-grain mix, these are called masa-ware and are not considered defects. Usually, it appears as a hard break so, unless it is rather large, it will generally not impede its practical use. This imperfection is known as kitae-ware and can appear on the blade, base, and on the ridge of a sword. These very small tears can appear if the steel layers have not completely welded together during the tempering process. In all these cases, the shinae are imperfections that can create a blade vulnerable to bending and stress and therefore not one that you would want when fending off an adversary. When they are of an almost smoky color and appearance, they are known as moe-shinae. When may of these lines are formed together they become mukade-shinae or “centipede-shinae”. If you are to look at a sword carefully, you can see some lines on the base, blade, and ridge. It is a defect, but in Japan, it has long been called tsukinowa or the “ring of the moon.” This attractive manner of naming these defects shows a long held tradition in Japan to see imperfection as a large part of the whole of an object and thus something to be admired for its aesthetic beauty, if not for its practicality. If this appears near to the sword point it is called mikazuki or “crescent moon.” This can appear on both sides or just one side of the blade. The cracks that appear along the forged surface are called hagarami. When that hagire is at the tip of the sword it is called karasu-guchi or a “crow’s beak.” Practically speaking, these can be quite detrimental in using the sword, but this is not considered a draw-back for swords that are meant to be display items.
#Katana blade crack#
When a crack appears in the tempered edge and extends to the blade it is called hagire. There are certain types of kizu that are actually appreciated for their beauty. Recently the sword is valued more as an artwork for appreciation rather than its actual use. This kizu may cause problems during actual use and for authentication.
![katana blade katana blade](https://www.lyuesword.com/u_file/1905/photo/f5e9c05496.jpg)
As it is forged repeatedly, there are cases where impurities are not completely removed or small mistakes during the forging and tempering process can cause kizu (flaws) in the sword. The Japanese sword is primarily composed of tamahagane (steel made from iron or black sand).