About Tatara
Tama-hagane and the Japanese sword
Tama-hagane is steel with a carbon content of 1% to 1.5%
and has the chemical composition best suited for edged tools. The carbon content
of sage-hagane is approximately 0.7%, while that of knife steel is 0.1% to
0.3%. Their compositions make them exceedingly malleable. The amount of chemical
impurities present with all these types of steel is extremely low; one can
say that they are particularly pure elements for use as steel material.
When compared with modern-day steel, the older steel types possess the unique
characteristic of being rich in oxygen. For this reason, there are many oxidized
inclusions in the portion of iron slag (the non-metal inclusion) found in the
steel. The oxidized inclusions are extremely soft compared to the inclusions
found in normal steel. They are easily stretched, and through repeated smelting
become finely dispersed and impervious to damage. This is what makes Japanese
swords particularly strong, produces extremely intricate and beautiful patterns
in the blade, and allows the steel to be highly polished.
While non-metal inclusions in normal steel are undesirable, the inclusions that
are widely dispersed in Japanese steel are a positive factor that reproduces
natural elements through repeated smeltings. In this sense, compared to modern
steel it is possible to say that wako (Japanese steel) contains extremely pure
natural elements.
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| Top Grade Tama-hagane (Wako Museum) |
Given that the natural elements in wako (Japanese steel manufacturing through tatara iron working, or tama-hagane) are extremely pure, it possess the following characteristics:
- It can be easily forge welded.
- It can be hardened through heating, does not bend, and is sturdy.
- Given that it is easily polished, good cutting edges can be produced.
- It does not rust easily.
- Beautiful tempering patterns can be created on Nihonto because the steel's baking range appears clearly.
