Several raw materials are needed for the process of clay burnishing: Recipe: clay + borax + iron powder + carbon powder (the ratio is 1:1), plus charcoal with an equal amount of carbon powder. Iron powder is recommended to use rusty iron, which can be ground down with a sander and then sucked with a magnet; clay with raw clay; borax is a sodium borate sandstone powder, which is not the main character in the work of burnishing, and the ratio should be appropriately low. In fact, borax is also used in modern gas welding as an equivalent = antioxidant Simply put, earth is used to cover the knife tire so that the edge is exposed, and then the quenching process begins. Only on Japanese knives do you cover the edge with earth and burnish it. But it also depends on the practice of the knife. Clay burnishing is not used on steel Japanese knives. The ultimate goal of cladding and burning the edge is to make the edge and the body differently hardened. Since the process of clamping steel has already made the hardness of the blade and the body not the same, so the soil burning edge is absolutely unnecessary. Chinese general now can be common ancient swords and knives because most of the clip steel so most of the whole body quenching, do not need to cover the soil, and the Japanese clip steel sword is the same. Burning the edge to change the hardness of steel is useful to the iron is useless, so no good knifemaker to do all iron burning edge knife. Quenching: steel will change the way of crystallization because of the temperature rise, in the temperature reaches 727 ~ 911 degrees (depending on the amount of carbon) or more, into a kind of crystal called MARTENSITE (MARTENSITE), at this time, the red-hot steel into the water or oil, due to the instantaneous cooling of the crystallization can not be changed back in time, and was fixed, called quenching. MARTENSITE crystallization is characterized by hard and brittle, and the volume is larger than the original. Water quenching speed is the fastest, and the hardness obtained is high. Oil quenching speed is relatively slow, the hardness obtained is relatively low. The wind quenching speed is relatively slower, and the hardness obtained is relatively lower. Each has its own advantages and shortcomings, according to the different steel and the expected results of different and choose the most suitable heat treatment. The same piece of steel fire red, if not all into the water, only part of the soaking water, then not into the water part, due to the slow cooling and return to the original crystalline state, resulting in hardness and volume unchanged, called partial quenching. The soil-covered burnished blade is a kind of partial quenching. The soiled part of the blade is isolated by the soil, as if it was not put into the water, a straight blade. After localized quenching, the hardness of the edge is increased. After partial quenching, the hardness of the edge and the volume of the blade have increased, so it naturally bends in the direction of the back of the blade ---- Anti Chinese swords made of clamped steel don't need to be coated with earth, and can be put into the water after being red-hot, while all-steel swords need to be coated with earth. The whole steel has to be clad. Before hardening, of course, the sword has to be shaped and first sharpened. Ancient Japanese sword making edge process: the first step of making edge, will be such a strip of steel heated to red burning and hammer forging, repeated folding and extension, as few as seven or eight times more than 20 or 30 times, each time are hammered dozens of hundreds of hammers, the exercise is aimed at analyzing the debris in the raw material, so that it becomes a well-proportioned texture of the steel, the Japanese sword of the "ground muscle" is also derived from this. Folding and extension of the method is very much, ordinary "wood is wood, cross" in addition to "short book, folded wood, wood leaves" and other forging methods. In ancient times, there is no test equipment, so whether or not the steel all depends on experience and feeling. Outsiders can not peek into the hall of its mystery. The steel that had been tempered could be used to make blades, but the Japanese were not enthusiastic about it. Sungji knives were called "Maru Forging", "Cutting Edge Iron" or "Counting and Striking Objects". These knives could not be used in combat! To make a good blade, steel and iron must be properly combined to make a blade. Steel is hard and easy to break, must be added to the soft iron to assist, cooked iron is soft and easy to bend must be steel as the backbone. This kind of blade can be called a compound blade or jacketed blade. The common combination methods for Japanese blades are "Sanko" and "Kako". For details, "Honzanmai-ho," "Sifu-ho," and "Gomai-ho" are used. In addition, iron is used at the point where the blade is prone to break (the stem). Will not $ $ $ quality of materials by different hit Yan fusion into one, the whole blade texture balanced, can be said to be the craftsmanship of the most. At this point, the sword is initially shaped and can be quenched after trimming and grinding. The quenching of ancient Japanese swords: The quenching of swords must be heated in advance. Before heating, it must be coated with "burnt edge soil" on the edge, which softens the role of the blade. When heated, if the soil layer is peeled off, it will leave a fatal flaw on the blade, and in serious cases, the quenching will fail. There are different ways to apply the "burnt edge soil". Different schools have their own secret traditions. The knife body is covered with soil, so after heating the blade and the knife appear various edge patterns. Different schools of swordsmiths have different methods of applying the soil, so the edge patterns on their swords are different. Hardening is a fate-determining process for swords, and the process of forging and smelting can be seen as such. In order to see the color of the sword in the heat, it is often done in the dead of night. The silence of the night and the master craftsman gazing into the hot fire add a layer of mystery to the sword. Blade body burned to just when, from the furnace will be drawn out of the knife, into the water at the moment the knife workers must drink and blade body all without water, such as the sound of the burst of fire, no lack of unusual sound, water vaporization. After this quenching, the hardening of the blade is completed. The water temperature plays a huge role, quenching, water temperature all by word of mouth. After quenching also allow tempering treatment, the knife will be slightly heated and then let it cool naturally, the hardness of the knife and sword has no effect, the edge is thus improved.

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