A katana, or samurai sword, is basically a single-edge, curved sword worn originally by 13th-century Japanese warriors. Despite its ancient nature, this curved instrument remains an epitome of skillful engineering and Japanese creativity. The katana is considered to be a highly resourceful weapon on the battlefield.
How so? Weapons in the past were mainly designed to perform two basic functions: Slashing or piercing. The katana is forged out of two types of steel, making it suitable to perform both functions.
You could learn how to make this sword for either protective purposes or simply to add it to your home decor. You don’t have to be a skilled swordsmith hailing from Japan to do this. The katana forging process is not at all complicated. By following the steps below, you can forge your very own katana sword.
1. Steel forging
The first step is producing a solid block of the purest high-carbon steel, known in Japan as ‘tamahagane’, meaning ‘jewel steel’. The steel should be approximately 5.1 cm (2 inches) wide, 1.27m (5 inches) thick and a little over 0.9m (3ft) long. Shovel about 25 tons of river sand, which is high in iron, and charcoal, which is mainly composed of carbon into a rectangular furnace made from clay, originally known as a ‘tatara’. The charcoal acts as a key ingredient as well as fuel for the furnace. At temperatures above 2,500AF, the iron ore is reduced to steel and produces about 2 tons of tamahagane.
2. Carbon Dissolving
To ensure that the right amount of carbon dissolves into the steel, the tamahagane should not reach a molten state. When making a katana, it is advisable to use both high and low carbon for a sharp edge and toughness respectively. The absence of one of these will cause it to either go dull too fast or become too delicate. Open the tatara on the third night of smelting, using the right degree to expose the high-carbon content from the newly made steel pieces.
3. Removal of Impurities
This tedious process involves heating, hammering and folding to ensure complete combination of carbon and iron. Once this is done, the undissolved impure remnants (slag) are drawn out the finished product can be weakened by any remaining content besides carbon and iron. When the slag is completely drawn out, you are able to determine the concentration of carbon in the tamahagane by how far it reacts to the continuous pounding.
4. Sword Forging
Once the slag is hammered from the tamahagane, heat the steel and shape it into a lengthy U-shaped channel. Hammer the steel until it fits exactly into the channel, then mix the two metals. The sword’s outer shell and razor sharp blade is formed by the hard steel while its core is formed by the hard steel. The balance of the two metals gives the katana its durable nature.
This far, the katana may look complete but it’s not Paint a thick coat of charcoal powder and clay that will act as an insulator. Do this on the back edge and upper side, but leave the sharp edge partially coated. This will not only protect the blade, but also give it its characteristic wavy appearance, which will later be emphasized after polishing. Place the almost-finished katana into the fire for heating at a temperature of slightly below 1,500AF.
6. Curving of The Blade
This is the most critical of the steps. Plunge the katana into water immediately after pulling the already hot katana from the fire. This process is known as ‘quenching’. As little carbon is contained in the sword’s back edge, they are able to contract at a more favorable rate as compared to the front edge which is basically high-carbon steel. The distinctive curve is brought about by the difference in the degrees of contraction and speed.
7. Blade Polishing
The fully forged katana sword is now ready for polishing. The next two weeks will be used to hone the sharp edge of the sword. Rub the blade meticulously with stones that are particularly meant for this, otherwise known as ‘water stones’ or ‘polishing stones’. They are mainly made up of particles of hard silicate that are combined with clay. When in use, more silicate pieces are exposed as the clay gradually fades off. This guarantees high polishing quality throughout the stone’s life. Each polishing stone is composed of finer silicate particles that do not at all interfere with the steel.