What I did was about a 1/4" on just the spine and matched it on each side of the blade with a cardboard templateLove the look, should research this, but how thick do you put the mortar on? I am guessing mortar on top do to edge being hardened.
Never thought of using a template for a Hamon - good tip.What I did was about a 1/4" on just the spine and matched it on each side of the blade with a cardboard template