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How to Make a Good Harmon (Temper Line)

How to Make a Good Harmon (Temper Line)
Brian Townbelin says that one of the hardest things to do well is a simple straight hamon called a suguha. Steve Schwartzel used his katana to demonstrate what a suguha is. In fact, Steve's realization of suguha on such a long leaf adds to the sense of ceremony.

Learn about the visual representation that Harmon does well.

For centuries, Harmon has been a mark of excellence in forging blades.

Strikingly its distinctive lines, often dissecting the middle of a blade with different heat treatments, it showcases a set of skills highly valued by top swordsmiths and swordsmiths. In addition, the difference between a good hamon and a non-compliant hamon can help manufacturers, owners, and users understand the expected performance of the blade itself.

Basically, think of a Hamon as the dividing line between the hard and soft or more malleable areas of the blade. Everything above the Harmon is softer, which means making the back of the blade malleable and therefore tougher. In other words, the blade will bend but not break. At the same time, everything below Harmon is harder, which is better for staying sharp.

How to Make a Good Harmon (Temper Line)
Emiliano Carrillo points out that the hamon should be continuous, with no areas that fall off the blade. Francesco Picchinen and Denis Mura offered such a Harmon in their Bowie collaboration. According to European Technologies (eurotechni.com), the blade material is C130 carbon steel, a grade of steel that makes it possible to get a "nice Hamun" with a total length: 13 inches.

"There are several factors that make the edge pattern successful," explains Emiliano Carrillo, a blacksmith at the Sun and Stars Forge. "The first two are practical.

The hamon should be continuous; No part of it should come off the blade. It should be tall enough that the knife can support sharpening and edge material removal throughout its service life without biting into soft material. For kitchen knives, this can be slightly lower to the edges, as the geometry will have to be adjusted if a large amount of edge material is removed.

"The rest is my own opinion, purely subjective. I am a blacksmith who works in historical traditions, so when it comes to the Harmon aesthetic and technique, my work draws on traditional Japanese metalwork.

"I think a good Harmon should be lively, fluid, and show your imagination and artistic eye," Emiliano continued. "It should have nice ups and downs and look like it was drawn with a brush on a knife edge. There should be ASHI, which is a hardened area inside the hamon dripping towards the edges. Sometimes, a repetitive theme, such as three cedars or cloves, can be used to guide the way you want to design. ”

ABS专家smith Mike Quesenberry也认为好的hamon有一些显而易见的特征。

"First and foremost, a good Harmon doesn't go to the forefront," he said. "It's a no-no, because it brings soft steel to where you want hard steel. I want a bigger transition zone, and you can trust the Japanese to start it. As technology evolves over the centuries, they discover fragments from Harmon that bring power to the edge. ”

ABS guru smith Brion Tomberlin adds that even if the manufacturer is completing the grinding process with a 120 grit size, the right hamon can be seen.

"The Japanese have a lot of terms to describe what you see and want to see in a nice hamon," he comments. "You can spend years working on these. For our purposes, you want it to be very noticeable and make a very clear demarcation from the hardened area to the softer area. Additional effects, such as ashi, are bundles of cloud-like structures hanging down from the main line, which are nice and show control. ”

Steel selection

How to Make a Good Harmon (Temper Line)
Brion Tomberlin noted that low-alloy steels such as W2, W1, 1095 and 1075 have had the greatest success in producing premium Harmon. ABS apprentice Smith Jesse Hu forged the 8.5-inch blade of his classic integral chef's knife from the W1. Overall length: 14 inches.

Successes or setbacks in the Harmon process start with the right steel, highlighted by Blade Magazine Knife Hall of Famer/ABS Master Steve Schwartzel.

"The choice of steel is crucial," he said. "You want a simple carbon steel that has 0.70 to 1 percent carbon, and people are doing the 'amazing' job with the W2 steel formulation, which is a very simple steel. The time-temperature-transition curve is important, and the alloy broadens it. Too many alloys in the steel won't transform fast enough to get to the Harmon pattern you want. ”

Tomberlin added that the most successful low-alloy carbon steels were seen, including W2, W1, 1095 and 1075.

"Manufacturers should look at the certification of the steel, look at the composition," he advises. "You need a steel that's low in manganese because manganese promotes deep hardening, not the shallow hardening that we want. We want the austenite to quickly convert to martensite when quenched to obtain high hardness, and shallow quenching steel is exactly what we need. Can you reach Harmon with other steels? Yes, there are some cases where the manganese content is lower, but they usually don't have the activity or effect you want to see. My first choice is W2. ”

Create a Hamon

How to Make a Good Harmon (Temper Line)
Brion Tomberlin describes Ashi as "a slender cloud-like structure hanging down from the [Harmon's] trunk, nice, showing control." "Elliott Robinson provided an ample supply of ASHI on the 5-inch blades of his fighter. Blade Material: U10A Carbon Steel.

According to Carrillo, after the heat treatment and hardening process has developed the desired hamon, creating a strong visual aesthetic is a process in itself and varies from one blacksmith to another.

"All manufacturers have different ways of polishing their Harmon that evolve over time or adapt to specific projects or aesthetic needs," he said. "My technique has evolved over time, but it works for 90% of my job, and it's a great way to practice bringing out all the activities you want to see in steel."

For his technique, Carrillo grinds the blade to a 220 grit size; Use a hard backing of sandpaper to polish it to 800 grit; Clean the blade thoroughly using acetone, dishwashing detergent, or rottenstone, while making sure water does not collect on it; etching it in ferric chloride; Use fine sandpaper to completely remove oxides; Assemble; Then there's the oil.

Quesenberry遵循类似的协议。

"I have a sharp blade in front of me, and I'm going to the hammer shop this weekend. "I'll grind it to 800 mesh, dip it in ferric chloride, and then depending on the strength of the iron, I'll wait until it's black," he said. Once it's black, I neutralize it with Windex and then use a 3-meter gray polish to make a nice, even, straight line, remove the black, get the white, and make the ashi look great. ”

Fake Hamon

How to Make a Good Harmon (Temper Line)
Emiliano Carrillo equipped his K-Tip Gyuto with a handful of clay hamon. The handle is bird's eye maple, and as with the saya (sheath), it includes a black walnut liner and a bamboo menugi (ornament) to keep the blade in place.

To eliminate a common problem, blacksmiths confirmed that none of the knives were Harmon. As Carrillo puts it, "There may be areas of decarbonization on the cutting edge that could be mistaken for Harmon, but that's only at the surface level." ”

At the same time, some factory-produced blades may etch a fake hamon on the blade to make the piece more attractive to potential buyers.

"If a Hamon is etched, you usually see a very clean line," he added. "It didn't have any blur or the blur you wanted to see on the real hamon. The fake ones are generally very white, too regular, and not metallurgical. ”

How to Make a Good Harmon (Temper Line)
Like Kyle Hansen's serious hunting knife shown here, even small knives like folding knives and hunting knives can provide Harmon with a solid canvas.

Every now and then, Tomberlin sees a fake hamon and says that the technique for implementing it is completely different from the real article.

"This is usually done with selective etching or different polishing techniques," he advises. "It's hard to explain how to discern, but if you see one compared to a real Harmon, it immediately stands out, often because it's too regular to have any effect. In addition, there is often a very clear line of demarcation, from high polishing to etching, which is particularly common in some overseas works. ”

What makes a good and bad Hamon

Distinguishing between good and bad ham may take practice. In some cases, the differences are noticeable, but in others, they are more subtle. Professionals have seen it.

"The biggest problem with a Harmon who doesn't do well is fade away in some way, or, yes, off the edge of a knife," Tom Berlin said. "If the hamon disappears from the edge, it means that your edge is not hard in that area, which is not good. The main reason for this is that the clay coating is too thick and that the blade is not heated properly when it is heated to the quenching temperature. The main problem I see is that Harmon is on the verge of collapse. As long as you have a hard edge, you have a Hamon.

How to Make a Good Harmon (Temper Line)
According to Emiliano Carrillo, the hamon should be tall enough for the knife to support a lifetime of sharpening and removing edge material without biting into the soft material on top. Will Newham won his Best Chef's Knife title at the 2023 Sydney Knife Show.

"Poor polishing can also show up. A well-done harmon takes time before and after quenching. Trying to cut corners on polishing will certainly show itself. As for the lack of movement in the hamon, such as being straight instead of having mountains and valleys, I was told a few years ago that one of the hardest things to do well is a simple straight hamon called suguha. ”

Schwartzel saw the crispness of a good Hamon and acknowledged that heat treatment and polishing techniques were the key to achieving this.

"In the early days of ABS (American Blacksmiths' Society), we used edge quenching to get hamon, which is the backbone of ABS today," he said. "In the tests now, you rarely see Harmon because you don't see enough polish to get you through the test. I can't get it out with a buffer. It's almost like a metallurgical polish, so you can see the particles in the steel. ”

The well-done hamon itself represents an art form, and Quesenberry is impressed by the current wave of artistic impressions.

How to Make a Good Harmon (Temper Line)
ABS apprentice smith Aidan Garrity equipped his V-44 repro with a 10.5-inch blade hamon with hints of ashi. Blade Material: W2 Tool Steel. Handle: Carbon fiber. Overall length: 15.5 inches.

"People have 'Americanized,' and I think you could say, I can be a decent Harmon. But some people definitely did," he said with a laugh. "They can paint with clay and heat treatment processes. You have to be careful not to over-refine the grain structure of the steel, especially in W2 shallow quenched steel, otherwise you won't get good results. It has a dance. ”

The perfection of the Harmon process, from beginning to finish, the temperature of steel and clay, quenching and hardening, has fascinated blacksmiths and admirers of finished products for centuries. Looking to the future, the possibilities are endless.

However, the awareness of good and bad products even further increases the real appreciation of the process.