The creation of a custom hand forged Carter blade starts with cleaning the shop and giving all of the tools and machinery a little check and regular maintenance. During this time I’m gathering my thoughts and mentally shutting out unrelated matters. By the time I light the forge fire to get started, I am fully concentrating on focusing all of my energy into the blade to be created.
The axe that will split the wood to start the forge fire is carefully sharpened by hand on my Japanese wetstones. This task is vitally important as the results from this first endeavor will set the mood for the rest of the work day. This attention to detail makes all the difference in the end product.
The freshly-honed Japanese axe is tested by shaving the soft hairs on the inside of the wrist. This step puts me in the right frame of mind, reminding me that a super scary sharp blade is the intention of the work at hand. "Concentrate on the task at hand" is one of my favorite sayings.
The wood to start the fire is cut and split, a ritual that I greatly enjoy. There is a wonderful satisfaction in converting wood to fire, as any campfire enthusiast can attest to.
The forge is first checked and adjusted as necessary, as the fire bricks which form the forge are laid in place without any bonding cement. Free-standing fire bricks allow me to adjust the shape and size of the forge as necessary according to what I'm heating in the fire. The split wood is stacked in the forge.
The forge is lit in preparation of heating the steels that will be forge-welded together to become the blade. The fire is fueled by a combination of pure pine wood charcoal from Japan and blacksmithing coke, a form of purified coal. The resulting fire is very clean and free from impurities that could harm the blade. It is also extremely rich in carbon which will be absorbed by the steel, thus enhancing its qualities.
A bar of the best Japanese carbon blade steel, Hitachi White Steel, is slowly and thoroughly heated in the forge. It is carefully forged under the power hammer and a small piece roughly 300mm X 10mm X 5mm is cut from the end and coated lightly in flux powder.
A bar of the best Japanese mild steel (Gokunantetsu) is also heated and then skillfully split down the middle with a hot chisel...
... resulting in a void just large enough for the previously prepared carbon steel.
The carbon steel core is then placed into the void (you can see the flux powder on the steel core)...
... and then any empty space is forced out of the void under the power hammer.
Here you can see the heat bleeding out from the billet as the core is perfectly alligned in the center of the mild steel.
The billet of steel is marked with a hot chisel indicating where the carbon steel core ends, and then marked a second time where the billet will be cut free from the mild steel bar.
The billet of Gokunantetsu and carbon steel is sprinkled with flux, a powder consisting of borax, boric acid and mild steel fillings. The flux will melt into a honey-like liquid at high temperatures and protect the surfaces to be welded from scale formation.
The billet is returned to the fire and carefully placed under a layer of coke embers making sure it heats evenly in the neutral to carbonizing layers of the forge. This not only prevents loss of carbon, but it actually increases carbon content of the billet steel so your hand-forged Murray Carter knife has the highest carbon content possible to maintain an edge so hard and so sharp it is capable of shaving steel from an anvil and maintaining that edge longer than any other knife you will ever own!
The fluxed billet is painstakingly heated to just the perfect temperature -- too low of a temperature and the steel will not perfectly weld; too hot and the steel structure will be damaged from excessive grain growth.
Just when the billet has reached the proper forge welding temperature, a bright yellow color, it is briskly removed from the coals, placed under the dies of the power hammer and gingerly struck, permanently welding the steel core to the outer mild steel. The power of the blows is gradually increased and the steel is worked throughout the whole billet. If the steel is so hot that sparks are jumping from it, it is too hot and must be cut off and thrown away. The steel has been irreversibly damaged and would never make a high performance blade. In this picture, molten flux (not sparks), can be seen spurting out from the welding layers.
Great concentration is neccessary to successfully forge weld. The billet must be struck by the hammer in such a way as to allow the molten flux to squirt out of the seams that are being welded. Even with protective leather garments, this flying molten flux has a tendency to find it's way into the smith's clothes and shoes, burning as it penetrates. The smith can either calmly let the flux extinguish itself in his skin, or start jumping around in search of relief and ruin the steel being welded!
The forge-welded billet is cut using the hot chisel at the point where it was marked earlier. The hot chisel is hammered almost through, but leaving just a very thin web of steel so that the hot chisel does not cut into the bottom anvil of the power hammer.
The web of steel purposefully left from the cutting is so thin that the billet almost falls off of the bar it was attached to.
The welded billet is heated several more times in the fire and forged to the desired thickness and shape. As the smith gains experience and confidence with the power hammer, more and more of the forging work can be accomplished using this incredible labor-saving machine. Letting the machine do the brute-strength work allows me to concentrate on other important details.
While most of the forging can be done with the awesome power hammer, fine detail forging is still done by hand. The hammer I'm holding is the traditional Japanese bladesmith's hammer that was passed on to me by my teacher, Mr. Sakemoto, 16th Generation Yoshimoto Bladesmith, and was made by one of his ancestors.
Here the profile of the back of the blade is being carefully forged.
Each time the blade is returned to the fire during forging, the blade is further purified in the clean, carbon-rich environment. With each forging operation, I’m able to forge a little bit more of myself into the blade as well. The blade is forged to within 10% of its final dimensions.
Once the blade is forged to its final thickness and approximate shape, a pattern, or template, is scribed onto the blade. I have over 100 kitchen cutlery templates and over 50 outdoor knife templates that I can use as a guide when making knives. In a later step, the blade will be cold-forged which will slightly alter the shape, making each knife a truly custom piece.
Using a special pair of Japanese heavy-duty metal shears, the excess steel from around the edges of the blade is trimmed off. These shears are able to sever steel in excess of 1/4 inch if preheated.
The trimmed blade is then returned to the forge fire...
...heated to a dull cherry-red color and then inserted into a bucket of rice straw ashes to cool slowly. This anneals the blade which is the first step in heat-treating steel.
Annealing relieves stresses in the blade resulting from the forging process and allows the grains in the steel to re-align themselves in the strongest possible formation. This also allows for the intense scale removal step coming next.
The blade, being cool enough to handle, is held over a slight depression in a stump of wood. The blade is hammered over the depression, knocking off any forging scale that is on the blade. All areas of both sides of the blade are hammered until all the scale has been removed.
The blade is hammered cold under the power hammer, a process known as “cold-forging.” This process further refines the grain structure in the blade and induces just the right amount of tension in the steel to give the finished blade the legendary cutting ability that the best Japanese blades are known for.
The final profile of the blade is meticulously shaped on the bench grinder. This step defines how the finished blade will look. One milimeter here or there can change the whole look and "feel" of a blade.
The blade is stamped with some of the same stamps that my teacher passed on down to me. Two of my stamps, “mitsu boshi” and “honkei,” have been in use for more that 16 generations. If your blade has a Carter Cutlery stamp, you are guaranteed to have one of the best blades in the world.
If the blade has a full tang, holes are drilled at this point to attach the handles later. The overall balancing point and “feel” of a knife can be adjusted by drilling more or less holes in the handles. These additional holes also serve to hold the epoxy cement used later to bridge from one handle scale to the other.
The blade is checked for straightness and slight twisting and corrected before preparing for heat treating. The trick to straightening blades is knowing how to properly diagnose them.
The blade is coated in a special clay mixture which will allow the blade to fully harden when it is later plunged into a quenching bucket of water. The consistency and viscosity of the clay has to be just right to achieve the desired effect. In Japan, this skill is considered so difficult to master that it is a vocation all by itself.
A bucket of aged still water is heated to a luke-warm temperature by inserting red-hot steel bars. The temperature of the water is critical for optimum quenching. Quenching Japanese carbon steel blades in water is the best way to obtain the full potential they have to offer.
I always heat-treat blades in a dark room as this is the only way I can accurately see the incandescent colors of the heated steel. This step requires the most focused attention of any step in bladesmithing, as the overall cutting performance of the finished blade depends on a perfect heating prior to quenching.
With a sound that is as unique as it is impossible to express to those who have never heard it, the blade is plunged into the water, forever sealing its fate as a blade. There is no turning back at this point, no touch-ups or re-try’s!
As the blade cools from 800 to 250 degrees Celsius in 0.6 seconds, the steel contracts violently. Then from 250 to 35 degrees the steel rapidly expands. There is so much stress in the steel during this rapid contraction and subsequent expansion that sometimes the blade can literally pull itself completely in half like a banana! An oil quench wouldn't be as risky, but nor would the blade reach its maximum potential either.
The quenched blade is then reservedly heated near the fire once again, just enough to raise its temperature in order to temper it properly. Too much heat at this point and the blade will be ruined.
During the tempering process, the blade is intermittently sprinkled with droplets of water. The behavior of the water indicates the temperature of the blade. When the droplets just begin to dance off of the blade, the tempering is done.
Now that the blade has been completely heat-treated (annealed, quenched and tempered), it must be checked for straightness before it is ground and polished. Quenching thin blades in water brings out the absolute best properties in steel such as optimum hardness and toughness, but it is such a severe quenching medium that it can induce bends and twists in the blade. Correctly inspecting a blade for problems involves a very intensive five-step examination procedure.
A special hammering technique is used to correct slight bends and twists in the blade. It takes years and thousands of blades to tune one’s eyes to the subtleties of straightening. A Carter blade will be inspected and straightened at least 7 times during its construction, ensuring that a it will be the straightest blade you will ever own.
The blade is then carefully ground on a slowly rotating Japanese water stone. First, the secondary edge (the part of the blade just behind the cutting edge) is ground, and then the primary edge (the cutting edge) is established. All this grinding is done AFTER heat-treating, ensuring consistent hardness and toughness throughout the whole blade. The water on the stone keeps the blade cool thus protecting the superior metallurgical properties of the steel.
A visual paradox -- sparks coming from a cool water soaked blade! Hitachi white steel is one of the only steels that I know that will do this, adding to its mysterious nature.
The roughly-ground blade then endures some rigorous testing. The heel, belly and tip of the blade are used to shave steel filings off of the edge of my band saw table. Only blades that are hard enough to do this continue on to the next steps.
My blades must not only exemplify outstanding hardness, but they must exhibit amazing toughness as well. The thinly ground edge of the blade is visibly forced to flex against the pressure of my thumbnail and then released to see if the edge will spring back to its original shape. This is an extreme test, pushing the steel beyond normal expectations for cutlery. If the steel is too soft, the flexed portion will stay flexed after pressure is removed. If the steel has large grain structure (not good; the smaller the grain structure the better), the edge will chip under this enormous pressure.
The blade is polished to improve its stain resistance and to enhance its blade geometry.
A high-quality material is hand selected to become the handle of the knife. Here a beautiful piece of desert ironwood has been cut down the middle of the wood grain to create a "book-matched" pair of handle scales.
The wood is fitted to the tang of the blade and holes are drilled through the wood, using the holes already in the tang as guides. If care is taken to position the wood scales just right, it will almost appear as if the steel tang "grew out" of the wood, that is to say, the wood grain naturally flows from one side of the handle to the other.
The ends of the handle scales towards the blade are chamfered and polished. This step is done before attaching the handles to the tang to avoid scratching the finished blade surface later. This is a fun step because the polished chamfers give me an idea what the finished handle is going to look like.
The handle scales are examined for symmetry before they are attached permanently to the knife. All Carter knives get the utmost care and attention to fit, finish and symmetry.
The surfaces to be glued are cleaned with acetone to ensure perfect bonding. Two-part epoxy is carefully measured out and thoroughly mixed. It is liberally spread on the inside of the handle scales and then the scales are attached and clamped on the tang of the knife.
After the handles are clamped in place, the excess epoxy is cleaned from the front of the chamfered handle scales. It will be impossible to clean this area after the glue cures (hardens). The three pins that keep the handle from shifting on the tang while the epoxy cures are removed after the glue has "set" but not completely cured. New pins will be inserted and then peened, adding to the overall durability of the handle.
The excess epoxy from each batch of mixed epoxy is allowed to fully cure and then it is given a strike test on the surface of the anvil. If the epoxy was equally dispensed and thoroughly mixed it will shatter like glass when it is struck with a hammer. Shattered epoxy means that the handle is perfectly attached to the blade.
The handle is then shaped and finished to the final dimensions on grinders and sanders. Each handle is sculptured for the perfect balance of function and beauty uppermost in mind. The finished handle should feel comfortable and natural to hold. It will allow the most efficient flow of force from the users hand to the cutting edge of the blade.
New pins are inserted into the pin holes, trimmed to just the right length and then skillfully peened to almost twice their original size. The heads of the peened pins further secure the handle to the tang of the blade. The epoxy and the pins guarantee the security of the handle for the life of the knife.
The blade is then clamped in a special “knifemaker’s vise” and the handle is sanded with extra-fine sandpaper by hand. Several times during the sanding, the knife handle is held in the hand to check for optimum comfort. It is my belief that tools to be held in the hand should be finished by hand.
The finished knife is hand sharpened on Japanese fine water stones. The only way to make a knife as sharp as it can be is to master the art of hand sharpening blades.
Here is where all the careful forging and heat-treating comes together. Using the “three finger test “ of edge sharpness, the blade is checked for “scary sharp,” first at the heel of the blade...
...then the belly of the blade...
...and then at the tip of the blade. If the hairs on the back of my neck aren’t standing up at this point, the knife fails the test!
I’ve retired my safety razor and taken to shaving only with one of my hand-forged knives. A newly finished knife is a great opportunity to get clean-shaven. Here I am shown shaving with a neck knife, but I’ve done it with my kitchen knives many times.
Here she is. Wow, was all that hard work worth it! I sure am happy for the lucky customer that gets this knife!
The fruit of my labors -- the result of 20 years of bladesmithing, 13,425 completed knives and untold amounts of sweat, blood and tears! I don't think I'll ever grow tired of it. For more, visit us at www.cartercutlery.com.
