Sunnobi Tanto Yaki-ire
Sunnobi tanto are larger than ordinary tanto (nagasa above 1 shaku/30cm) and may have sori (curve) similar to ko-wakizashi.
A mixture of natural clay, polishing stone powder and ground charcoal masks the back the blade. When heated and plunged edge-first into cold rainwater the edge cools faster and hardens while leaving the masked area tough and resilient.
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