Q & A with Yoshida san

First Yoshida san explained me his forging.
He put the two deba he forged on the table. He explained showing the front side (omote) that the next step is grinding before the heat treatment (HT). After grinding the yellow broken line will become the shinogi.

On omote you can only see the soft steel(jigane) surface. The surface did not have hammer marks and that is his craft. With grinding the lower part of the shinogi hard steel(hagane) will come out at the next step comes out.

I found a border line at the backside(ura) and asked him if it is the border of jigane and hagane (jizakai). He answered yes. Then he draw a line (the red broken line) with his finger and said with a modest smile:" For top line knives the jizakai is here. You put more hagane on and most of the ura is hagane"
I asked if he will grind the ura to make it concave.

"Look at the hammer. The lower part is not flat. It is convex to make the concave ura (urasuki). You should not grind the hagane so much. You must forge the ura concave."
"To hammer the steel is very important. It becomes better steel. Even stainless steel will get better. The resulting kitchen knife cut better, it is easier to sharpen and it will hold the sharpness longer"
Then he left to search something. He came with a piece which would be a santoku I think.

He put it on the table and said:"This is the thin laminated precursor of a kitchen knife which is mass produced in a factory nearby. You cannot hammer/forge these thin laminates. I use these thick bars for forging"
And indeed I could only find thick bars in the workshop.

              to be continued....