Satetsu (iron ore sand, seen in the bottle) and pine charcoal are smelted in a very hot fire (a tatara) for three days and then left to cool. The resulting mass of steel at the bottom of the tatara forge is called tamahagane (bloom steel), from which flat wafers are then later forged.
Tamahagane is very porous, has an uneven carbon content, and is full of impurities. This is the raw material from which samurai swordsmiths forge their legendary blades.
The tamahagane for the forging project is sitting on the anvil. Preparations get underway by sweeping the area, starting the fire and priming the power hammer with some TLC.
Starting the fire…
…and priming the power hammer with some TLC.
Murray holds the heated tamahagane in a pair of tongs in order to forge the material flat so as to have material for forge welding. It is the most difficult step in the whole process.
Forging the raw tamahagane.
The tamahagane has been successfully forged flat and cut into small wafer-like pieces which can now be stacked prior to forge welding.
The first few forge welds are rather spectacular as a higher than normal heat is applied to the steel to initiate welding through the irregular surfaces and high percentage of impurities. With each successive forge weld, the steel will become cleaner and more homogenous, and therefore the forge-welding temperature will be lower. Sparks during forge welding are generally not a favorable sign, but unavoidable in initial tamahagane welding.
The steel is carefully heated to forge-welding temperature in the forge again. A traditional mixture of pine charcoal and clean burning coke is used to fuel the fire. This fire will aid in refining the steel and can add carbon to the steel if necessary.
Here the steel is being folded for the first time -- a precarious endeavor as unwelded chunks from the outer edges fall of and scatter about. It is up to the discernment of the smith whether to gather them together and try to weld them back into the billet to add mass. This can be costly in terms of time. Keeping the momentum going while there is heat in the billet is one of the secrets to perfect forge welding.
When the billet is returned to the fire to be heated for the next step, utmost care has to be taken to keep it heating evenly and thoroughly. The fire itself has to be well maintained by cleaning it free of clinkers and keeping it stoked with enough fuel. This is part of the bladesmith’s dance.
The steel is repeatedly forge welded in a slow and very deliberate manner. It is carefully forged on the flats only until it is finally solid enough to be hammered on edge. This is a turning point in the process, from which great speed and progress can occur.
Making great progress.
With each hammer blow, the steel feels more and more solid.
Murray is confident at this point that he will end up with something to show for his efforts.
At this point, the billet of tamahagane is looking great. It folds and welds like solid steel.
Another forge-welding heat. Here you will notice the absence of dazzling sparks, but can see the molten flux flying off as the steel is struck with the hammer. The closer the blade gets to completion, the lower the temperature the blade is heated in the fire.
The blade is forged to shape, checked for straightness and twist, and then is annealed in the bucket of rice straw ashes.
The blade is ground to the final profile. Notice the safety equipment.
Very unique quality of sparks emanate from the tamahagane. There is no commercial steel that compares to this. The Japanese post vise is beautifully silhouetted in this photo.
The blade is coated with Japanese heat-treating clay and placed into the fire…
…and the lights turned out to see and feel the proper temperature for quenching.
The quenched and tempered blade is then straightened and ground to a cutting edge on the Japanese rotating waterstones. A light etching to reveal the hada (steel grain), a test shave on Murray’s beard, and the blade is ready…
…to be delivered to the customer who commissioned the whole project. Start to end time was just 3.5 hours. Murray made it just in time for his 5pm workout at the gym!
