Thread: The art of forginational Geographi

Edit: thread title accidentally messed up. Seems I cannot correct this anymore.

Yesterday evening (while lapping my stone) I was watching a brilliant documentary on National Geographic about the forging process of a katana.
They rerun the documentary on wednesday at 15:00 CET.

Some interesting tidbits:

There is 1 place in Japan where they smelt the iron for katana. they use a very pure iron sand that is found locally. the smelting process takes 3 days and nights. during that time, the smelt master (who is 70 years old) continuously monitors the oven without sleeping.

Little lumps of steel are selected by the smith, and hammered into larger pieces. These large pieces are hammered and folded several times. Then iron and hard steel are hammered together and flattened to form the sword shape.
One thing I did not know is that until it is quenched, the sword is as straight as an arrow. Before heating it, it is covered with thin layers of clay and mud. of varying thickness
When the sword is quenched, the edge cools quickly because it is thin, and has only a thin coating of clay. the spine cools slowly, due to it being thicker and having a thicker coating.
The asymmetric cooling causes the sword to bend. It is this process that creates the curvature of the katana.
If the sword is not perfectly left-right symmetrical before quenching, or if there is a n uneven clay coating, the sword also bends to the left or right, and it has to be thrown away. 3 months of work down the drain.

The sword is polished and sharpened by a sword polisher. He has a large collection of stones that can cost thousands of dollars each. Polishing and engraving takes another 3 months.

The end result is a sword that can cost up to 50000$ or more if it was made by a famous smith and polished by a master polisher.

You really have to watch that documentary if you can. it is worth it.