Charcoal forging a traditional tanto style blade from half of a reclaimed horse carriage leaf spring at 4x speed (total actual forging time including heating was about 2 hours). Serious students of the forge can watch the full process version here: https://youtu.be/y7fROs7i8-U
The two distinct stages are sunobe and hizukuri…sunobe establishes the geometry and proportions, and hizukuri is putting in the bevels and creating the final shape. The final dimensions take a little extra care as this blade is being forged very closely to a traditional kata.
The finished forging has a subtle recurve and a slightly dropping spine compared to the kata as the process of yaki-ire will cause the spine to curve upwards.
Shear steel is a very old and somewhat rare form of steel produced by increasing the carbon content of wrought iron using heat and charcoal to create a reduction atmosphere and then forge welding and folding layers together to homogenize the billet. The finished blade has distinct visible layers telling the story of its history.