There are various Japanese swords made of Tamahagane steel, but what is Tamahagane?
It is a kind of steel that originated from Japan for producing classic Nihonto. In a sense, this metal composes of carbon and steel ore. The steel ore comes from iron sand while carbon is from charcoal.
These components undergo smelting and heating in a classic bloomery called the Tatara. Once heated, the combination will undergo melting in a Tamahagane or steel slag.
What’s in a Tamahagane?
The Tamahagane is made of Satetsu or iron sand. There are two types called Masa Satetsu and Akome Satetsu. Masa has higher quality while Akome has lower quality. Murage is the one who chooses the amount of mixing parts.
Depending on the needed results, the Murage combines one or more kinds of sand.
A good Tamahagane has 1% carbon content and should not have more than 1.5%. Yet historical Tamahagane usually had 3% to 4.5% of carbon. This made it into cast iron, resulting into very fragile pieces.
How is Tamahagane Produced?
The first step in producing Tamahagane is to smelt the layers of iron sand and charcoal. This is where the Tatara is used, and the Murage will select the type of iron sand for making this.
A swordsmith categorizes the kinds of carbon steel available. These are the Hocho Tetsu (low carbon steel) and the Tamahagane (high carbon steel). Next, he will forge the Tamahagane in altering layers.
During the process, the smith can continue folding up to sixteen times. However, if the Tamahagane doesn’t go through folding, the assorted distribution of carbon will produce weak points on the sword.
Do take note that super alloy steel like L6 steel is a modern material used in some swords. These are extremely homogeneous and do not to go through the folding process.
The Nittoho Tatara can stay lit for a period of three weeks. It can also only be used during the deepest time of winter since it is when humidity is low. Having this type of weather condition allows the creation of purer steel.
In this three-week period of production, each forge can make a total of three sets of steel. Each of the batches would take a total of seven days to progress then complete.
How long does it take to produce a Tamahagane?
The entire duration of producing a Tamahagane goes on for 36 to 72 hours. This is a total of a day and a half to three days depending on the number of people working on this. It also depends on the amount of metal obtained.
Here, it is necessary to add sand every 10 minutes, and turning over the mixture constantly.
Once completed, people working on this will break the clay tub then remove the steel. The best steel will be on the edge of a metal block since the spot is where oxidation is stronger.
This Tamahagane’s quality is clearly seen via its color. Bright silver pieces are efficient for making very good blades.
What is Orishigane?
Because of the regulated and limited supply of Tamahagane, prices go sky high. Thus, there is a huge competition among smiths when it comes to acquiring steel.
Due to this limit in supply, a lot of smiths utilize a steel mixture called Orishigane or leftovers. These can sometimes consist of steel shavings and old nails. Orishigane also includes other kinds of materials containing iron.
By enriching steel with more charcoal, smiths can control how much carbon is present in Oroshigane steel. Classic swordsmiths use smaller types of Tatara.
What is the Forging Method of a Sword Using the Tamahagane?
Here, we will share the different processes of forging with the use of Tamahagane.
Subeshi / Kowari
When speaking of heated Tamahagane, it goes through a pounding process. This occurs until the material gets thin before it breaks into pieces. The smith uses a hammer to complete the process.
During Shitagitae, before heated the pieces are neatly arranged. After this, the material is pounded thinly and then folded for a second round. This goes on for about 12 to 15 times.
The Agekitae is where finished steel is cut into pieces then reorganized. It will undergo another process of heating. The produced grain or Hada differs based on the steel pieces’ arrangement.
How is Today’s Production of the Tamahagane?
The production of Tamahagane today differs from how it was in the past. The Japanese government controlled and managed steel production in this period.
Currently, exporting raw Tamahagane is illegal, especially before making it into a ready to sell item. Furthermore, production of this is only three to four times a year, making this type of metal rare. With that, it also drives up the cost for consumers.
The method performed for making the Tamahagane is generally labor intensive. The Nittoho organization manages and directs this process.
Generally, steel created via the traditional method and using a classic Tatara can be called the Tamahagane. There are only a handful of authentic pieces left in the country.
The Nittoho also manages the sales and distribution of iron sand & ore sand. They guarantee that all resulting steel reaches and meets their absolute guidelines.
Tatara and Tamahagane Outside Japan
If you live outside Japan, you are free to produce your own Tatara and smelt your own Tamahagane. Yet, you can only find the classic iron ore sand in Japan’s Northern tip. It is used in creating the Nittoho Tamahagane.
The Satetsu or sand is unique when it comes to its color and chemical content. Its colors are usually brown or green. This also has its own set of impurities that give the Tamahagane its unique appeal.
So if you have a forge that is up and running, you will not be able to replicate the features and colors of an authentic Tamahagane. This is unless you use authentic iron ore sand.