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“Dao” is the pronunciation of a Chinese sword. There is a Chinese saying which can be literally translated as “Dao, it is the way. It is used to slash so as to attack.” This shows that back in ancient times in Chinese history, Dao has been mainly used as a weapon for a long time. Dao is defined as a short-edged weapon with a single-sided long blade. It can also be referred to a tool used for stabbing, slicing, cutting and smashing.
The earliest metal Dao appeared in the Shang Dynasty(1600-1046BC) and they were made in bronze. In that era, as there was a high degree of brittleness in bronze, Dao was made very short so as to avoid breakage. And for the same purpose, the spine of Dao was also made quite thick and it was thus not as easy to handle as the short bronze Jian at that time (Jians are double-edged straight swords while Daos are single-edged, Jian has been translated as a long sword, and the Dao a saber or a knife). Daos were mainly used for cutting utensils, slaughtering cattle and sheep, or as a culinary appliance, they had not been used as a war weapon yet.
During the Warring States period (475–221 BC), Daos gave way to bronze-made Jians which were extensively used. The turbulent period that had gone on for a long time also contributed to the rapid development of the forging industry of cold weapons. Many experts in this industry rose up, and the forging technology of pattern steel which first appeared at that era, remains a prevalent trend nowadays.
During the West Han Dynasty (202BC – 8AD), Daos started to be used in warzones. The West Han Dynasty is signified as the era of iron and steel. Convoys were replaced by cavalries as the main force in an army, and thrusting weapons alone were not enough to do the job. What soldiers urgently needed were steel-made Daos that were efficient in killing their enemies.
The booming steelmaking industry transformed the army of the Han Empire into an invincible group of “Armored Fist”. The method of fried steel was evolved into the steelmaking technology, producing Huan Shoudao (Ring pommel sword) with a length of over 1 meter. For the nomadic cavalries who had no saddles and stables, the straight, narrow blade of the rough and inexhaustible Dao was a perfect tool for killing their enemies. Its back with 1cm thickness could also withstand violent slashing actions. One could imagine how lethal the Han Huan Shoudao was, as it was one of the thickest and heaviest Dao in ancient history. It was also a powerful symbol of the Han Dynasty. Until now, Huan Shoudao has become a classic and a memorable legend in the Dao history.
Two Old Methods
Before the Spring and Autumn Period (771-471 BC), the ancient smelting technology was in a relatively underdeveloped stage. Charcoal has used a fuel for iron smelting. The temperature of furnaces was relatively low as there was not much energy generated from the charcoal, the size of the furnaces was small, and the equipment was poor. The temperature required by iron smelting was not reached. As such, iron that was smelted was similar to a sponge-like solid block. Such a method was too time-consuming, and the texture of iron turned out to be not hard enough. It also contained too many residues.
Later, iron and steel smelting technology had reached its peak. From the unearthed relics, we can see that the Chinese had already got a grasp of this technology (at least its initial stage) at the end of the Warring States period. As constantly repeated heating was essential in the process of forging wrought-iron, the iron absorbed the carbon in the charcoal and the carbon content was increased. After taking away all the residues and impurities, steel was made as the finished product. Such a steel had a dense structure and the carbon composition was evenly distributed, it was very suitable to be made for weapons and Daos.
In the later stage of the steelmaking industry, when people were in the manufacturing process of utensils, they deliberately increased the times of folding and forging. A piece of steel had to go through dozens, sometimes a hundred times of burning and forging before eventually being polished to become a fine piece of steel. This kind of fine steel contains more carbon and it structure is denser, and the materials are more evenly distributed. Therefore, they usually have a very high quality and are often used to make Baodao (treasure knife) and Baojian (treasure sword), literally meaning that they’re made from very fine material.
The Fried Steel
From the middle to the late Western Han Dynasty(202BC-8AD), the Chinese developed a new steelmaking technology – ‘fried steel’. This is a steelmaking technology developed with the basis of cast iron smelting, through heating the cast iron until it turns into a semi-liquid or liquid state. Then, iron ore powder is added while stirring the mixture constantly, using the iron ore powder and oxygen in the air to remove a part of the carbon, residues are then removed before the steel is obtained. This is the technology of fried steel.
The invention of this technology marks a major breakthrough in steelmaking technology, enabling the industry to provide the society with a large number of affordable, high-quality wrought iron or steel, meeting the needs of production and war. The emergence of fried steel had also contributed quickly to the development of fried steel, which was used by people as a raw material. After numerous times of heating, folding and forging, a really fine quality steel was made. However, there still lies a shortcoming in fried steel and steelmaking, that is the skills of fried steel was complicated and not easy to learn. Steelmaking, on the other hand, was a very expensive process and demanded a lot of manpower and financial resources.
Spreading of the technology
As time passed by, the Han Dynasty became only history. After the Tang Dynasty (618-907AD) was established, people adopted a more advanced “irrigation method of steel” in order to replace fried steel, making their Daos even tougher and sharper. A hand guard had been added and the ring at the end of the handle was removed. At this time, we call this weapon Tang Dao (Mo Dao).
Tang Dao represented the peak of the development of Chinese cold weapons, not only did it witness the establishment, prosperity then the downfall of the Tang Dynasty, it also had a great impact on the Asian cold weapon culture.
The Innovator of Cold weapon Forging Technology – Qiwu Huaiwen
The person who was dedicated in promoting the ancient Chinese sword technology was Qiwu Huaiwen. He was a famous metallurgist and Dao-making expert in the Northern and Southern Dynasties (220-589AD). Before him, Chinese steel Dao was mostly fabricated by the Steelmaking that we mentioned previously. And you might remember – that making this kind of Dao was very expensive, although they generally had a high performance.
China started using the quenching technique as early as in the Warring States Period, but for a long time, people used water as a cooling medium for quenching. The Dao-making expert in the Three Kingdoms(220-280AD), Pu Yuan(a Dao-making expert in this period) and the others realized that different types of water can be used as quenching cooling media, and Daos with different performances could be obtained. However, there was a limitation of using one single liquid in the process. Qiwu Huaiwen had realized this point, so he used the “two-liquid quenching method” in the production of “overnight iron” sabre – first quenching in the urine of animals which has a high cooling rate, then quenching in the animal oils and fats which has a low cooling rate.
This results in getting steel with better properties, it can also avoid the limitations of using a single quenching (that is, single-liquid quenching). When the temperature of the workpiece is relatively high, the quenching medium with a relatively fast cooling speed is used to ensure the hardness of the workpiece. And when the temperature is relatively low, the quenching medium with a relatively small cooling rate is selected to prevent the workpiece from being cracked and deformed, also to give it a certain degree of toughness. The two-liquid quenching method is a relatively complicated procedure. Under the condition of no temperature measurement and temperature control equipment at that time, it was a very remarkable achievement because people had to completely rely on manual operation and experience.
The spine of the Dao and its cutting-edge play different roles, and therefore require different performances. Generally speaking, the cutting edge mainly plays a critical role in the killing, thus requiring a relatively high degree of hardness and sharpness. Therefore, it should be made with tough steel which has a high carbon content. The spine mainly plays a supporting role, which requires better flexibility so that the Dao does not break easily. The spine thus requires wrought iron that has a low carbon content but a high flexibility. Since Qiwu Huaiwen had a thorough knowledge of the above, he could skillfully combine wrought iron and steel in the production of the tool and making the best use of both materials. It not only satisfied the different requirements of different parts of the clip steel Dao, but also saved the use of a lot of expensive steel. With the promotion and popularization of the clip steel Dao, his way of the process is still in use today, and it has a far-reaching influence.
(In a traditional Chinese kitchen knife market, clip steel Dao is still very popular among ordinary families. Because of the particularity of Chinese culinary culture, it also determines the material for making Chinese kitchen knives. On the previous blog where it was mentioned that Li Ziqi uses her “magical tool” for a lot of occasions. Such a magical tool is a Chinese traditional kitchen knife and it is a 100% handmade clip steel Dao.)
Irrigation Method of Steel
The irrigation method of steel is one of the most outstanding achievements of China’s early steel-making technology.
Before the 17th century, countries around the world generally adopted the method of low-temperature smelting of wrought iron. Steel could not be melted, iron and slag could not be separated easily, and carbon could not be penetrated quickly. The Chinese then invented the irrigation method and successfully solved this problem, making an epoch-making contributing to the world. According to historical records, Qiwu Huaiwen’s irrigation method of steel is realized as followed:
- First, select an iron ore with relatively high quality, this can ensure that the iron smelted would be a good one.
- Then, the liquid of cast iron would then be poured onto the wrought iron, and after several times of smelting, the carburization of iron would turn them into steel.
Under this method, the cast iron and wrought iron are similar to “staying, lying together” (in Chinese: Su), the steel that is smelted is hence called “overnight iron”(Su Tie).
The irrigation method of steel is an amazing achievement in ancient Chinese steel-making history. Its advantages include:
- As a kind of carburizing agent, cast iron speeds up the carburization of the wrought iron and this is due to the high temperature after smelting. Smelting time is then shortened, and production efficiency can be improved.
- The wrought iron becomes steel after carburization. The cast iron will also become steel due to decarburization, which in turn increases the steel output.
- At a high temperature, substances like carbon, silicon, manganese, etc. in the liquid cast iron react with oxide inclusions in wrought iron, such a process can remove impurities, purify metal structures and improve metal quality.
- The irrigation method of steel is easy to operate and master. To obtain steel with different carbon content, one just has to make sure that the proportion of cast iron and wrought iron is appropriate, before proceeding to the next step – smelting.
After the Song Dynasty(760-1279AD) unified the Central Plains of China, the cold weapon forging industry began a new round of development.
As the making of Tang “horizontal Dao” or “cross Dao”, and Mo Dao were time-consuming and expensive, they were considered as a luxury in war equipment. Not only did it take a lot of time and money to equip the army with horizontal Dao and Mo Dao, but it was also difficult to repair them if damaged. Naturally, they were then abandoned.
What was used to replace them was a cheap and practical wide-bladed Dao, namely ‘Chinese great sword’.
An effective and inexpensive weapon would always be the first choice for military equipment. The luxurious Mo Dao and horizontal Dao gradually disappeared from the war scene. In the mid-late Tang Dynasty, an arc-bladed weapon called Tangdao had appeared, and was then preserved by the Japanese for its original shape. In terms of its production process, a lot of progress had been made after the hard work of generations of craftsmen.
A Mature Development
The Ming (1368-1644AD)and Qing (1636-1912AD) dynasties marked a mature development of the manufacturing of Chinese Daos. During this period, various forging industries had already reached the point of perfection.
In the late Qing Dynasty, China’s Dao manufacturing industry began to go down. From the beginning of the Opium War in 1840 to New China in 1949, China had experienced too many wars and destruction. The use of new weapons led by muskets made the use of traditional swords in wars becoming smaller and smaller. People were running out of clothes and food and they were trying hard to survive. They naturally couldn’t afford to spend time to make high-quality swords. Perhaps, the army of Dadao (Big Sabre) during the War of Resistance Against Japan signified the last glorious moment of Chinese Daos in a war scene.
In short, China’s Dao manufacturing had to face its decline.