Japanese knife expert, help?

Apr 19, 1999
Hi all! I've got a question regarding Hamon lines on Japanese tantos and i hope the experts on this particular field can help me.
What methods or stages create the Hamons? forging? Heat treating? tempering? Is it possible to make Hamon visible on 'stock removal' blades?
I have a friend who says that Hamon are made visible on hardening stage and not forging, is it true? Please help. Your assistance is very much appreciated, Thank you.
Your friend would be correct. The hamon is the hardening line created during the quench.

The Japanese coated their blades with a special clay before heat treat. When the blade is quenched in water, the clay acted as an insulator.

The spine was thickly coated, thus it cooled slowly making it soft. The clay coat on the edge was thin, and it cooled quickly, making it hard. How the smith apply the clay makes a big difference with how the hamon is shaped (straight, wavy, flowery, firey, etc). To the collector, the hamon is like the oil on canvas.

Forging and stock-removal all takes place before this step, so it has no effect on the hamon.

Some steels don't produce good hamons. Most notibly the air-hardening stuff. 10XX, W1/W2 steels turn out good hamon. 5160 is okay. Anything with lots of Chrom, Moly, Tungsten is going to kill the hamon.

[This message has been edited by tallwingedgoat (edited 11 September 1999).]
Hi, keninshiro, your name reminds me of a hero with seven scars...

A hamon first shows up when quenching it into water, as tallwingedgoat said. There are a few more conditions that determines the hamon pattern, impurity in steel they use, the temperature of heat-treat, quenching speed (of the blade not covered with clay), some tanto (not only cheap ones) has a cutting steel laminated in the center contrary to usual katana architecture that has edge steel on the surface and laminates a kinda spring steel at the center along the spine. Moreover there in Japan are "sharpsmiths" who do not make blades but are experts in sharpning and polishing katanas. Some of their polishing techniques help to show hamon clearly, or vaguely. Usually a kind of traditional acids are used to make hamons clear, but there surely are deceiving tricks of mean sharpmasters to buff up the tip to shine to disguise a hamon, like "hissatsu" knife does. As "Hissatsu" is a knife it's okay with it, but take care if you find too clear a hamon on a tanto in $1,000 price range!

\(^o^)/ Mizutani Satoshi \(^o^)/