Japanese Katana is made with complex "folded forging" craft. It may be hit by combat, and has experienced hundreds of years of history, so it may have a variety of flaws. As long as the practicality and beauty are not compromised, minor flaws will not affect the value of the sword. In fact, there are many so-called flaws, which are even important features of certain faction of katana sword.
The defects of katana can be divided into the following situation:
"Hagire" (see H) appears in "Kissaki", which looks like a crow's mouth.
Wrinkles appear on the blade, which means that it is easily bent.
When "folding forge", because the air penetrated into steel's folded layers, so that some of the folded layers could not be completely welded, there was a bubble hidden in the sword. After the sword is repaired and polished many times, the hidden bubbles may be exposed, affecting watch.
The back of the katana is damaged. If it is not serious, it will have little effect on the performance of the katana.
The embedded iron material. It means that there are defects were deliberately covered up in the area.
When "folding forging", some of the folded layers are not fully welded, and the blade may have vertical crack lines. If the situation is not serious and does not affect the katana's performance, it is acceptable.
Same as "Ware", but only appears in back of katana.
A cracked wound appeared on the blade, and the sharp angle of the wound was almost at a right angle to the blade, which was a bad situation. Not only unsightly, but also seriously affect the performance of the sword. In this case, as long as you apply a little force, the blade may break. If the sharp angle of the wound is oblique (more than 45 degrees), the chance of the blade breaking off may be slightly reduced. If the split is nearly parallel to the blade, it is called "Hagarami".
On the edge of the blade appears cracked wound. The bottom of wound has a round and no sharp angle. So the crack will not stretch out and the blade will not break. In fact, excellent Japanese swords have inherent characteristics to prevent sharp collapse, and swords that can appear " Hakobore" should also have certain quality.
If the carbon content in the steel cannot be evenly distributed, certain part of the blade will appear particularly dull and dull. The grinders may be able to remove the dark parts. However, excessive "grinding" will deplete the "skin iron" of the blade. If the "core iron" is exposed, katana's value will be greatly affected.
"Hamon" appears broken. Experienced grinders can use the "grinding" method to disguise it.
"Hamon" didn't pass the "blade zone", which may affect the visual effect, but the performance of the sword is positive.
If the sword has been re-quenched, the "center" part isn't be heated and cooled, so near the "blade area", will appear a shadow.