Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

A piece of hot high-carbon steel, which will become the cutting edge, has been placed on the orange-hot low-carbon steel body of a knife as part of the “forge-welding” process. An acidic flux powder has been placed in-between and on the metals in preparation for laminating them together into a single blade.

Men are like steel. When they lose their temper, they lose their worth.
Chuck Norris

While Beloved Customers are of course familiar with the features of the high-quality woodworking blades we purvey, some Gentle Readers may have little knowledge of the important details of Japanese woodworking tools. So in this article we will try to remedy that by examining some simple historical points common to woodworking blades around the world, as well as some details that make Japanese blades unique.

Your humble servant believes an understanding of these basic facts will aid Beloved Customer’s sharpening efforts, or will at least tickle Gentle Reader’s interest in Japanese blades. Please comment and let me know your thoughts.

Laminated Bi-Metal Construction

As discussed in previous posts in this series, before technological advances in the 1850’s steel was difficult to make and expensive. Consequently, it was standard practice not only in Japan but everywhere, including Europe and the United States, to reduce production costs by minimizing the amount of precious steel used to make axe, scythe, plane and chisel etc. blades. This was achieved by laminating smallish pieces of high-carbon steel to softer and much cheaper wrought-iron bodies through a process called “forge welding.”

Most chisel and plane blade blacksmiths in Japan continue to employ this lamination technique even today, not because of some navel-gazing infatuation with the archaic, but because it has serious advantages.

The best Japanese plane and chisel blades are generally comprised of a layer of very hard high-carbon steel called “hagane” (鋼) in Japanese, forge-welded to a softer low-carbon/no-carbon iron body called “jigane” (地金). We discussed both of these metals in the previous two posts in the series here and here.

Here is the key point to understand: When a blade made from a lamination of high-carbon and low/carbon steel is quenched, the sudden temperature change causes the high-carbon steel layer to become hard, even brittle, while the softer low/no carbon layer is unaffected and remains soft.

*A 30mm Hidarino Ichihiro* Atsunomi, approximately 12″ OAL.

Why go to so much trouble? One advantage of this construction is that it allows the cutting edge to be made much harder than is possible in the case of an non-laminated blade therefore staying sharper longer in use than softer blade. But why does lamination make this possible? Consider the absolute fact that a chisel blade made of uniform material heat treated to a uniform hardness of, say, HRC65 might cut very well, and stay sharp a long time, it will always break in use. Not just chip, but actually break in half. The softer low/no carbon jigane layer supports and protects the hard high-carbon layer preventing it from rupturing. Such durability is one hell of an advantage.

Another benefit of laminated construction is ease of sharpening. Remember, the harder a piece of steel is, and the larger the its area, the more work it takes to abrade it. But in the case of a laminated blade, the amount of hard-steel exposed at the bevel the user must abrade is just the relatively thin strip of shiny metal seen in the chisel photos above and below. Please also recall that the darker low/no carbon layer jigane is dead soft and melts away on the sharpening stones without much effort.

So the laminated construction of hard hagane to soft jigane produces a blade that is tough but at the same time hard, one that will become very sharp and stay sharp a relatively long time thereby improving work quality and productivity while at the same time reducing the time spent sharpening.

BTW, this is not a technique that was invented in Japan, it’s just the Japanese blacksmiths that continue to employ this ancient and clearly superior technique, at least, that is, for a little while longer. A word to the wise.

Laminated Blades in the West

If you have examined antique plane blades with wooden bodies you may have noticed many have blades stamped ” Warranted Cast Steel”

Despite being designated “cast steel” in England and America in past centuries, unlike Conan’s Daddy’s sword, or the orc blades made in the bowels of Isengard, plane, chisel and saw blades with this mark were not “cast” by pouring molten metal into a mold to form a blade. Rather the process to make the steel involved melting iron ore in a crucible and pouring it into molds “casting” a strip, bar, or ingot of high-carbon steel which is then forged to make the blade, hence the name.

This became possible only when the technology required to reliably and fully melt steel to a liquid state on an industrial scale was developed. Such steel was also called “Crucible Steel” after the crucible container used to melt iron ore.

This technology was widely used in the United States and Europe through the 1870’s. In fact, one steel mill is said to have been producing crucible steel until the 1960’s. Toolmanblog has an interesting summary on cast steel.

With few exceptions, these plane blades have a thin piece of high-carbon steel forge-welded to a soft wrought iron body, very similar to Japanese plane blades. I have reused a couple of these antique blades to make Krenovian planes and testify of their excellent cutting ability.

Chisels were also once made in Europe using this same lamination technique, although fewer examples remain extant.

Axes, hatchets, and many farming implements were also mass-produced up until the 1920’s in the US using a variation of this same technique with a “bit” of steel forming the cutting edge laminated to or sandwiched inside a body of low-carbon steel or wrought iron. Axes are still made this way in Japan. It’s a proven technique with a lot of advantages, but it does require a skilled blacksmith to pull off successfully.

The point I am trying to make is that blades made using forge-welded laminated technology were the very best available in Europe and the United States for many centuries.

Here is a link to a blog post by Paul Sellers where he praises the old chisels and laments the new.

U-Channel Construction

*A closeup of the 42mm Hidarino Ichihiro Oiirenomi* showing the lamination line between the steel cutting layer and low-carbon steel body of the blade

*The same 42mm Hidarino Ichihiro Oiirenomi*. Notice the hard-steel lamination wrapped up the blade’s sides to add rigidity.

*A 30mm Hidarino Ichihiro Atsunomi, approximately 12″ OAL. Notice the hard steel lamination forming the cutting edge at the bevel*. This is a beautiful lamination.

A beautiful hand-filed shoulder detail typical of Yamazaki-san’s work

The shape of the hard steel cutting layer laminated to the softer low-carbon steel (or wrought iron) body of chisels was historically a simple flat plate in Western blades. This is still the case for Japanese plane blades, axes, and farming implements. But if you imagine Japanese blacksmiths would be satisfied with such a simple design for all applications, you don’t know them well.

If Beloved Customer will carefully consider the blades pictured in the four photographs above, you will notice the lighter-colored hard steel lamination wrapped up the chisel’s sides forming a “U channel” of hardened steel adding necessary rigidity and strength. This is a critical detail for Japanese chisels intended to be struck with a hammer. Interestingly, Japanese carving chisels are not typically made this way, and are consequently structurally weaker.

Plane blades are not subjected to the high loads chisels experience and so would not benefit from this structural detail.

The Ura

Japanese chisel and plane blades, among others, typically have a hollow-ground depression called the “Ura” (pronounced “ooh/rah”) which translates to “ocean” or “bay,” located at what is called the “flat” on Western blades. Notice the polished hard steel lamination extending from the cutting edge to several millimeters up the neck. The black area surrounded by the shiny lands is the same hard metal, but has been ground to form a hollow called the “ura.”

This clever and effective design detail is unique to Japanese tools to the best of your humble servant’s knowledge. We will look at this design detail more in the next article in this series.

The Point

What does any of this have to do with sharpening? Allow me to focus what we have discussed previously.

These design details cleverly turn potential disadvantages into distinct advantages you need to understand when sharpening Japanese woodworking blades.

For instance, the layer of high-carbon steel laminated into our chisels and planes is usually 65~66 HRc in hardness. Western blades are made of a single piece of steel heat-treated to approximately 50~55 HRc to make the tool softer/tougher thereby limiting breakage. The extra hardness of the Japanese blade helps it stay sharper longer, an important benefit if your time is worth anything. This is good.

But if the entire blade were made of a solid piece of this extra-hard steel, it would a royal pain in the tukus to sharpen, I guarantee you. It would also break. Oh my, that would be bad.

The softer low-carbon/no-carbon steel or iron jigane body, however, is much softer and easily abraded making it possible to keep the hard steel layer thin, and therefore easily abraded, while protecting it from breaking. This is good.

Unlike the blade’s bevel, however, the ura (or “flat” as it is called in Western chisels) is all one-piece of hard steel. Without the hollow-ground ura depression, you would need to abrade all that hard steel at one time to initially flatten and regularly sharpen the blade, a necessity I guarantee would ruin your mellow mood even if you consumed massive quantities of controlled substances. But with the addition of the ura detail, we only need to abrade the perimeter planar lands (the shiny areas in the photos above) surrounding the ura. This is exceedingly good.

The ura depression makes it easier and quicker to not only sharpen the blade, but also to keep the “flat” planar (in a single plane). Without the ura, such a hard blade would be difficult to maintain planar and frustrating to sharpen. With the addition of the ura, the blade is genius.

An important skill to learn when sharpening Japanese blades is how to maintain the lamination and ura effectively. We will discuss this important subject more in future posts, including the final article in this series.

Conclusion

If you didn’t learn at least three new things from this post then you are either very smart or weren’t paying attention. ¯\_(ツ)_/¯

In the next installment in this bodice-ripping tale of romance and derring-do we will examine the hollow-ground “Ura” in more detail. It’s important enough to deserve a special post.

YMHOS

It is not my intention to be fulsome, but I confess that I covet your skull.”
― *Sir* *Arthur Conan Doyle, The Hound of the Baskervilles*

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Links to Other Posts in the “Sharpening” Series

Sharpening Part 7 – The Alchemy of Hard Steel 鋼の錬金術

An Alchemist and his assistants working late at night in his workshop.

Behold, I have created the smith that bloweth the coals in the fire, and that bringeth forth an instrument for his work.
Isaiah 54:16 KJV

In the previous post we looked at some of the supernatural aspects of making and forging steel. In this post we will examine some alchemical aspects of woodworking blades, in the particular the iron and steel used to make them and the related chemistry of sharpness and sharpening.

This post could be very technical, but your humble servant has simplified the description of chemical processes to make it easier for the non-technical Gentle Reader to follow. Please bear with me.

The Alchemy of Mutating Iron to Steel

When carbon is combined with iron in the right proportion, steel is formed. This mutation is easily accomplished nowadays, but for most of human history it was a fiendishly difficult, chancy, expensive process. No wonder those who could accomplish the deed were attributed with magical powers.

But just mixing chemicals does not yield a useful cutting tool. No, the blacksmith must make the steel hard enough to hold a cutting edge, but tough enough to endure actual work. The catalyst for this mutation is heat. The ability to create a fire hot enough to melt iron was, until fairly recently on the scale of human history, the biggest hurdle to producing quality steel consistently.

If steel is heated to within a specific range of temperatures (difficult to measure by eye) and then suddenly cooled, crystalline structures containing small, very hard and relatively brittle crystals called carbides form within a softer matrix of iron. These hard carbides supported in this rigid crystalline structure are what do the serious job of cutting, not the softer matrix.

At the extreme cutting edge, this structure might be compared to a modern circular saw blade comprised of a relatively soft body to which is attached very hard tungsten carbide cutting tips.

A steel blade dulls when the crystalline structure either shatters, or the pressure and friction of cutting wears away or cracks the softer supporting matrix, allowing the carbides to be torn from the matrix leaving behind gaps of soft, blunt metal. The larger the carbide clumps are and the greater the distance between them, the more easily they are shattered and torn away, and the duller a blade becomes with each crystal’s failure.

In a low-quality blade, and given the same amount of carbon in a fixed volume of steel, the crystals will form into relatively large and isolated clumps separated by wide rivers and lakes of softer metal, as seen from the viewpoint of a carbide. The steel will crack along these weaker pathways when stressed, and when cutting, the softer material in these lakes and rivers will erode first, leaving the desireable carbide clumps unsupported and vulnerable to failure.

A photograph of Shirogami No.2 high-carbon steel following heat treatment and tempering. In this case, the temperatures used were less than ideal resulting in the irregular crystalline structure shown. The black material is carbon, the grey material is converted steel, and the whitish areas are soft, unconverted iron, points of natural weakness and paths of failure in the steel blade, not acceptable in a high-quality hand-forged blade.

The same steel shown above but following quenching and tempering using proper temperatures. The converted steel crystals are small and more evenly distributed. Islands of unconverted carbon and lakes of soft unconverted iron do not remain. This is a sample of ideal high-carbon steel, and is typical of the crystalline structure of the blades of our chisels, planes and kiridashi.

In a high-quality steel blade, by comparison, and given the same amount of carbon in a fixed volume of steel, the crystalline clumps are comparatively smaller and distributed more evenly throughout the matrix making it more resistant to erosion, and the carbide crystals more resistant to damage. Such steel is called “fine grained,” and has been highly prized since ancient times for its relative toughness and ability to become very sharp and stay sharp for a long time. This is the steel preferred by woodworking professionals in Japan and is the only kind found in our tools. Without exception.

Sadly, this crystalline structure is not visible to the naked eye, and anyone who says differently is trying to sell Beloved Customer something brown and smelly, probably with a side dish of flies.

Impurities and Alloys

Other than excellent and abundant water, endless forests, mountains overgrown with wonderful trees, and diligent people, the islands of Japan are poor in most of the natural resources critical to industrialization, including iron ore, coal, and petroleum. Prior to the mass importation of such resources after 1854, the best source of iron been in Japan from black sand (satetsu 砂鉄) found in rivers. The article at the following link details some of these traditional Japanese production methods: A Story of a Few Steels

Regardless of their source, all iron ores naturally contain impurities such as phosphorus, sulfur, or silicon to one degree or another. When these impurities exceed acceptable limits, they can weaken the steel, make it brittle or tend to warp badly, or make heat treating results inconsistent. They are often expensive to remove.

Nagasaki Bay, the only Japanese port open to Western traders between 1639 and 1854, with primarily only Dutch ships permitted entrance.

There are three approaches commonly used to minimize the negative effects of these difficult-to-remove impurities. The first is simple avoidance of the problem by employing iron ore and scrap metal free of excess amounts of these contaminants. Such ore and scrap are available, but they are not found everywhere and are relatively expensive. For centuries, the purest iron ore has been mined in Sweden.

The second approach is to add purer iron or carefully sorted and tested scrap steel to the melting pot thereby reducing the percentages of the harmful contaminants, a technique called “ solution by dilution.”

Nakaya Takijiro’s saw forge, originally made for forging swords

The third fix is to add chemicals such as chrome, molybdenum, nickel, tungsten, vanadium and even lead to the pot forming steel “alloys.” In their simplest formulations, these chemicals help overcome the detrimental effects of natural impurities, specifically those related to brittleness, warping and unpredictable heat treatment. Some additives will make the steel more resistant to abrasion and corrosion, or even easier to cast, drop-forge, or machine.

Intentionally adding chemicals to steel produces what are called “steel alloys.” Some steel alloys have serious advantages over plain high-carbon steel in mass-production, reducing material costs by improving the performance of cheaper lower-grade iron ore and scrap metal, improving manufacturing characteristics, and achieving higher productivity with fewer rejects even when worked by low-skill workers.

But the addition of these chemicals is not all blue bunnies and fairy farts because edged tools made from high-alloy steels typically have some disadvantages too. For instance, additives like chrome, nickel, molybdenum, vanadium and especially tungsten are costly. And due to the crystalline structure produced produce, such steel alloys simply cannot be made as sharp as plain high-carbon steel, and are more difficult and time-consuming to sharpen by hand.

Some manufacturers cite the higher costs of high-alloy steels to justify higher prices for their products. However, what they never say out-loud is that labor costs are much much less when using high-alloy steel because skilled workers are not necessary. And because high-alloy steels produce fewer rejects, quality control is easier, overall productivity is higher, warranty problems are fewer, and profitability is increased. Indeed, without high-alloy steels, manufacturers would need to train and hire actual skilled workers and professionals instead of uneducated seasonal workers thereby destroying the world’s current Wally World mass-production model. Egads! Walmart’s shelves would be bare!

Our blacksmiths make only professional-grade tools for craftsmen that value ease of sharpening, edge retention, and cutting performance above corporate profits. They charge more for plain high-carbon steel blades than for high-alloy steel products because labor and reject costs are higher.

So if a manufacturer brags about the excellence of the high-alloy steels they are using, rest assured increased profits are their motivation, not improved cutting performance. Caveat emptor, old son.

Japanese Steels

The best plane and chisel blades are made from plain, high-purity, high-carbon steel. In Japan, the very best such steel is made by Hitachi Metals mostly using Swedish pig iron and carefully tested industrial scrap (vs used rebar and old car bumpers), and is designated Shirogamiko No.1 (白紙鋼 1 号 White-label steel No. 1). They also make a steel designated Shirogami No.2 containing less carbon. Another excellent steel for plane and chisel blades is designated Aogamiko No.2 (青紙鋼 Blue-label steel) No.1 and No. 2.

Aogami steel, like Shirogami steel, is made from extremely pure iron, but a bit of chrome and tungsten are added to make Aogami steel easier to heat treat with less warping. Aogami can be made very sharp, but it is not quite as easy or pleasant to sharpen as Shirogami. Some of the plain high-carbon Swedish steels are also excellent.

If worked expertly, either of these steels consistently produce the highest quality “fine-grained” steel blades.

Let’s compare the sharpening characteristics of these two steels. To begin with Shirogami steel is easy, indeed pleasant, to sharpen. It rides stones nicely and abrades quickly in a controlled manner.

Aogami steel, by comparison, is neither difficult nor unpleasant to sharpen, but it is different from Shirogami steel in subtle ways. It takes a few more strokes to sharpen, and feels “stickier” on the stones, but it will still produce fine-grain steel blades and performs well.

Inexperienced people lacking advanced sharpening skills typically can’t tell the difference between blades made from Shirogami, Aogami or Swedish steel and steels of lesser quality. But due to the difficulty of forging and heat treating Shirogami or other plain high-carbon steels, a blacksmith that routinely uses them will simply be more skilled and have better QC procedures than those whose skills limit them to using only less-sensitive high-alloy steels.

Professional Japanese woodworkers insist on chisel blades made from Shirogami No.1 steel. Some prefer Aogami No.1 for plane blades believing the edge holds up a bit better. At C&S Tools our plane blacksmith prefers to use Aogami because it is easier to work and more productive (especially in the case of carving chisels), but for a little extra they are happy to forge blades from Shirogami Steel.

I own and use Japanese planes made from Shirogami, Aogami, Aogami Super, Swedish steel, and a British steel called “Inukubi,” which translates to “dog neck,” a commercial steel imported to Japan from England (Andrews Steel) in the late 1800’s. Of these, Shirogami No.1 steel is my favorite. It’s a matter of personal taste.

Beware of a plane or chisel blacksmith that refuses to use plain high-carbon steel and tries to charge you more for blades made from Aogami or Aogami Super steel.

The Challenges of Working Plain High-Carbon Steel

What makes plain high-carbon steel so difficult to work, you ask? Your humble servant has never even forged a check much less a tool blade, but I will share with you what the blacksmiths I use and swordsmiths I know have told me in response to this question.

First, plain high-carbon steel is much more difficult to successfully heat treat because the range of allowable temperatures for forging and heat-treating is narrow. Heat it too hot and it will “burn” and be ruined. Quench it at too high or too low a temperature and it will not achieve the desired crystalline structure and/or hardness. Miss the appropriate range of temperatures and the blade may even crack, ruining it. Yikes! Please see the numbers and photos in the article linked to above.

Second, even if the temperatures are right, plain high-carbon steel has a nasty habit of warping and cracking during heat treating resulting in more rejects than steels with additives such as chrome, tungsten or molybdenum. Strange as it may seem, when the crystalline structures that make steel useful form during quenching, they increase the blade’s volume. This change produces differential expansion causing the metal to warp, a troublesome characteristic that can be more or less controlled, or at least compensated for, by a skillful blacksmith, but it takes real skill, extra work, and a bit of luck. Not just any old Barney can do it consistently, so when working plain high-carbon steel, a blacksmith needs to know his stuff and pay close attention.

Other than wastage due to rejects, it doesn’t cost more to forge and heat-treat a blade made from plain high-carbon steel, but it takes serious skills and dedication to quality control to make a living working it for 5+ decades.

Let me give you an example of skill and experience as it relates to warpage management of plain high-carbon steel.

The photo below is of a swordsmith the instant before he quenches a glowing hot sword blade made of tamahagane, a traditional type of plain high-carbon steel made from iron sand, in a water trough. Notice the condition of his smithy: he is working in the middle of the night, the time when the best magicians and alchemists have always done the most difficult jobs because temperatures are easier to judge without inconsistent sunlight confusing things. His posture and facial expression are tense because he is about to roll the bones and, in the blink of an eye, either succeed in the most risky part of making a sword, or fail wasting weeks or months of work and thousands of dollars worth of materials. Notice how straight the glowing blade is before the plunge.

A Japanese swordsmith with a blade made from high-carbon Tamahagane steel poised for quenching. The blade is straight at this point in the process. He has invested months of work into this blade to this point and a misjudgment or even bad luck in the next second can waste it all. *Not a job for the inexperienced or timid*.

Note that the quantity of crystalline carbides formed in a Japanese sword during the quench is greatest nearest the hard cutting edge, and cause that area of the blade to expand and warp the most. The swordsmith therefore forges the blade straight before quenching it in expectation of it warping to the intended curvature when the crystalline structures at the cutting edge form, as seen in the photo below. This curvature is an intentional design feature that takes years of experience to achieve in a controlled manner.

Related image — After quenching, the resulting warpage is dramatic. The swordsmith must plan for this distortion and shape the blade accordingly prior to the quench if he is to avoid unfortunate results. Notice the mud applied to the blade before quenching to control the formation of crystalline structures and achieve differential hardness. Tool blacksmiths are faced with the same challenges on a smaller scale but more frequently.

If the swordsmith intended to make a straight sword blade, he would have a forged a reverse curvature into the blade to compensate for the warpage that occurs during quenching. Plane and chisel blades exhibit similar but less dramatic behavior due in part to the moderating effects of the low/no-carbon lamination.

ãæãããæ²ããããããåããããè¿½æ±ããæ¥µéã¾ã§éãä¸ããããåã¨ããå§¿ã«ãåå¹´ãè¶ããæ¥æ¬åã®æ´å²ã¨ãçãããã¨ã®ãã¹ã¦ã®åãæ³¨ãã åéå¶ã®å§¿ãæµ®ãã³ä¸ããã — A photo of both sides of a modern sword with the warpage being an intentional design feature

The thinner the piece of steel being heat-treated, the more unpredictable the warpage developed and more likely the blade will be to develop fatal cracks. Within limits, simple warpage can be corrected to a limited degree in thin blades during the first few seconds after quenching and/or tempering by bending and/or twisting the blade while it is still hot and malleable. These techniques do not work well in the case of thicker plane and chisel blades, however, so experienced blacksmiths don’t rely solely on corrective measures but anticipate warpage beforehand and create a curve or twist in the opposite direction when forging the blade to compensate. This takes skill and experience, and even then, some rejects are unavoidable.

Chemical alloys like chrome, molybdenum, and tungsten greatly reduce warping and the risk of cracking, so their benefits are huge.

None of this is mystical, but tools made from plain high-carbon steels such as Shirogami steel require more skill and experience than those possessed by factory workers, much less Chinese peasants, so mass-production is nearly impossible, labor costs are higher, profit margins are smaller, and advertising budgets are non-existent. No wonder such tools get little attention from the shills in the woodworking press.

While modern chemistry has unveiled the mystery of steel, it has only been during the last 70 years that metallurgical techniques were developed making it possible to understand the Mystery of Steel, and the tools to scientifically control the Alchemy of Steel are only a few decades old, a short period of time in human history.

The manufacture and working of steel are still magical processes that are the foundation of modern civilization. Be not deceived: while computer nerds and ijits with MBAs take all the credit, without the alchemy of steel and the skill to work it, human life on this planet would be short and brutal.

If you have good sharpening skills but haven’t yet tried chisel or plane blades made from Shirogami, Aogami or Asaab K-120 Swedish steel, you’re missing a treat.

In the next article in this magical series we will examine the genius of the soft iron component found in quality Japanese woodworking blades. Whether cat, bat or owl, please explain the details to your familiar to prepare them for the excitement to come!

YMHOS

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Relevant Posts

The Story of a Few Steels

Sharpening Part 6 – The Mystery of Steel

“The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science.”
Albert Einstein, The World as I See It

The blades we are considering in this series of articles about sharpening are made from iron and steel, so it makes sense to examine these materials from the viewpoints of sharpness and sharpening. Let us consider some of the supernatural and legendary aspects of working these materials first.

Steel Magic

Steel is a magical substance. Since ancient times, the blacksmiths that worked it were sometimes seen as gods, sometimes as wizards, and always as essential. Regardless of local traditions, the power blacksmiths possessed to combine and shape the elements of earth, wind, water, fire and even spirit into the tools and weapons of everyman’s trade was seen as magical.

Even the blacksmith’s forge and anvil were seen as magical in and of themselves, and rituals incorporating them were widely believed to keep evil at bay, provide good luck and blessings, and even to cure ailments.

There were several extremely famous magical blacksmiths back in the mists of time. Please allow your humble servant the honor of presenting two of them.

Vulcan the God

The bas-relief stone carving in the photo above is of Vulcan, the Roman god of fire and blacksmithing, also known as Hephaestus to the Greeks. This carving was excavated at Herculaneum, located in the shadow of Mount Vesuvius near Pompeii. Herculaneum was an ancient Roman town destroyed by volcanic pyroclastic flows in 79 AD. The word “volcano” comes from the word Vulcan, so a stone carving of Vulcan retrieved from a town totally destroyed by Vulcan’s namesake is tragically ironic in the extreme.

*Die Schmiede des Vulkan (The Forge of Vulcan) by Velázquez, Diego 1599–1660) Museo del Prado, Madrid, Spain.*

The painting by Diego Velázquez above is from a scene in the Roman poet Ovid’s Metamorphoses where the god Apollo visits the god Vulcan in his forge to tell him that Venus, Vulcan’s wife, is being naughty with Mars, the god of war. Apollo is on the far left and can be recognized by his crown of laurel and shining aura. Vulcan stands next to Apollo with a shocked and incredulous expression on his less-than-beautiful face (nice abs, but the ‘stache needs a lot of work). Vulcan’s assistants have stopped their work on armour (decidedly 15th century in style) astounded by both the sudden appearance of Apollo and the news he delivers.

Obviously, Venus and Vulcan were not a happy couple. Legend says that whenever Venus was unfaithful, Vulcan grew angry and beat hammer on anvil so fiercely that sparks and smoke rose up from the top of Mount Etna on the island of Sicily, under which he had built a forge, creating a volcanic eruption. You could say he blew his top (ツ).

Perhaps Apollo is sharing this tidbit of news just to help out his old buddy Vulcan, or perhaps his reason for snitching is malicious. Whatever the reason, I think it’s safe to assume people loved drama in the 1600’s too. Nothing new under the sun.

Your humble servant’s point is that Vulcan (Hephaestus) was not only worshiped in ancient Greece but had a presence in popular culture that ranged from before an Etruscan tribe drained the swamps that became Rome in the 10th century BC, to as late as the 1600’s. And I won’t even get into Trekkie lore. Now that’s an influential craftsman.

Wayland the Smith

Wayland the Smith was another famous blacksmith, metalworker, and magician. He was said to be a Lord of the Elvish folk who learned his trade from either giants or dwarves.

While not as old as Vulcan in human history, Wayland’s legend survives throughout Europe, and the products of his forge were central to heroic traditions of many peoples and kingdoms long before the days of the Viking longboats.

He is credited in Norse, Germanic, and Anglo-saxon legends and literature with forging magical objects of great renown, including rings of power (no, Professor Tolkien didn’t invent the concept), the impenetrable coat of ring mail worn by Beowulf during his epic battle with Grendel, the magical sword named Gram that Sigurd used to slay the dragon Fafnir, and even King Arthur’s sword Excalibur. Not just scribblers, but even Alfred the Great, king of the Anglo-Saxons (c.886~899AD) on the island that would later become England, wrote of him.

The chains on the legs of the statue above probably represent his maiming and imprisonment on an island at the pleasure of an evil Norse king upon whom he took a bizarre revenge involving unconventional drinking bowls and jewelry. Is Wayland’s slavery one of the reasons blacksmiths have wrapped chains around their anvils since ancient times, or is the purpose just to secure the anvil and mute the bright ringing song they sing? Another mystery…

Wayland’s influence in modern times is not insignificant. For example, Leonardo Da Vinci’s fascination with flying machines was probably stimulated by the legends of Wayland building and using a winged contraption to escape his slavery. And unlike Daedalus’s deadly device in Greek legend, Wayland’s glue didn’t melt.

File:Gowy-icaro-prado.jpg — Daedalus (the bald guy) and his son Icarus (the falling guy) using wings to escape the island of Crete, home of labyrinths and monsters. Against his father’s advice, Icarus flew too near the son melting the wax securing the feathers that made the wings function. “Oops,” Murphy chortled.

The legends of Wayland the Smith were once deadly serious matters.

In a lighter vein, the writings of J.R.R. Tolkien, the author of the most popular works of written fiction in human history (no kidding), were influenced by these same legends.

The Blacksmith’s Shop

While some blacksmithing traditions such as those involving Vulcan and Wayland are decidedly pagan in origin, others fit well with Christianity. For example, the ring of the blacksmith’s hammer on his anvil was once believed to strengthen the chains that bind the devil in hell barring him and his demons from God-fearing folk’s hearths. In darker times in human history the blacksmith’s workshop was believed by many to be a safe haven from evil forces, one that Satan and his imps actively avoided.

Below is a download link to a charming story about why blacksmiths ring their anvils and how to make sure a horseshoe brings you luck at work and at home. I encourage you to read it.

Legend of the Ringing Anvil Download

The Japanese Smithy

If you have ever spent time in small one-man traditional smithies of the sort where our blacksmiths labor to produce the tools we provide to our Beloved Customers then you know the other-worldly atmosphere typical of such workplaces. Imagine wattle and daub walls and exposed , twisting, rough-hewn wooden roof beams blackened with 70+ years of soot, the compacted but lumpy dirt floor, the darkness of carefully-managed sunlight (the better to judge metal temperatures by eye), the bitter smells of charcoal fumes, straw ash, flux, hot steel and smoking oil; the roar of forced gas forges; the sounds of grinders and the antique leather belt systems that drive them; and finally the terrible racket and vibration of spring hammers and ringing anvils. A man that could work alone in a place like that 12 hours a day for 65 years is not afraid of your garden variety demon, no siree Bob.

It’s quite a sight to see a craftsman working in such an environment. They often start late in the morning to avoid noise complaints from the neighbors, and work until late at night doing heat treating when sunlight won’t interfere with the colors of the hot metal.

By noon their arms are black to the elbows and charcoal smudges are on their faces. The sight of a small, wizened 82 year-old man with strong sinewy arms scowling into the face of yellow-hot steel as he hammers the hell out of it is like a scene from Dante’s Inferno. Something of the ancient magic of Vulcan and Wayland can be felt in such places.

In the next post we will examine some alchemical aspects of the Mystery of Steel. Until then, I have the honor to remain,

YMHOS

Mr. Takagi working on his wet grinder in August 2018.

YMHOS

Nakaya Takijiro’s forge, originally made for swords, now dedicated to forging handsaws.

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Links to Other Posts in the “Sharpening” Series

Relevant Posts

The Story of a Few Steels

Sharpening Part 5 – The Sharp Edge

The gem cannot be polished without friction, nor man perfected without trials.”
Confucius

This post may not be as entertaining as previous ones in this series about sharpening Japanese woodworking tool blades: No swords or artwork or handsome Hollywood philosophers, I’m sorry to say. But with this post we will roll up our sleeves and get some work done.

Your humble servant prostrates and begs forgiveness if Beloved Customer’s tender sensibilities are in any way offended. Many Beloved Customers and Gentle Readers already know most of what is presented in this post, but it is my fervent hope that one or two useful gems may be discovered.

You know the difference between the quality of work a sharp edge performs compared to that of a dull edge. Cuts are clean and finished surfaces are smooth, maybe even shimmering. Your tools are happy, singing and chirping as they cut away. But have you given thought to what a sharp edge really is?

Since the purpose of sharpening is to produce this condition in a blade, a clear understanding is useful, so we will consider the basics in this post.

We shall also examine the naughty cutting edge that seems sharp but suddenly and unexpectedly dulls after just a little use. Would it be useful to know how to detect such a cutting edge before it fails wasting your time and money?

Let’s begin with bedrock.

The Basics

A cutting tool is essentially a wedge, with two flat sides meeting at an angle. Applying force causes it to wedge apart and sever materials, be it wood, metal, meat or mushrooms.

The geometry of this wedge is critical to its performance. At one extreme, the angle could be 90°. It won’t be sharp, it will be hard to push, and it will crush and tear wood instead of cutting it cleanly, but it will be durable.

At the other extreme, the wedge might be made more acute, say 3°. It could be extremely sharp indeed, but it would be too fragile to cut anything but whip cream for long. The point is that the sharp edge is a compromise, acute enough to cut well, but not so acute that cutting pressure and friction will make it dent, roll, wear away, crack or chip easily.

The effective blade must have a bevel angle that will cut the intended material well, but at the same time supports the thin cutting edge from premature wear and damage for a relatively long time. The words “well” and “long” in the previous sentence are where the magic lies. We will examine these important points in future posts in this series.

Wood Shaving’s Eye View

Ideally, the extreme edge of the ideal metal tool’s extreme cutting should be perfectly smooth and only a single molecule thick. In the real world, cutting edges are rougher and wider, but still manage to cut pretty well.

Examine a sharp cutting edge under a microscope, and you will see imperfections. A dull blade will look even worse of course, showing dents, rips, and even cracks.

knife edge_microscope800 — The edge created by an 800 grit stone

Using a blade wears away and damages the cutting edge rounding and flattening it, destroying the geometry that makes it an effective wedge. Sharpening is the process of (1) restoring the intended wedge geometry; and (2) removing defects from the meeting of the wedge’s sides by abrading metal from one or both sides down past any damage, leaving a relatively clean, uniform wedge with minimal defects. This is the sharp edge. It is what the wood experiences. It requires effort to achieve, but it ain’t rocket surgery.

The most difficult part of achieving the two objectives listed above is making nothing from something, in a place that cannot be seen. Now that’s a Zen koan if I ever heard one.

Building confidence in one’s ability to achieve results at the microscopic level is not easy. The key is to understand the goal, and to consistently follow reliable procedures. I will describe those goals and procedures in future posts in this series.

Edge Failure

The ideal cutting edge is uniformly sharp, but few edges in the real world meet these severe criteria at the microscopic level where it matters most. A blade may be sharp in some places, and dull in others. Likewise, a blade may cut well for a while and then dull quickly and suddenly. We have all experienced these irritating failures.

One common cause of these inconsistencies and failures is that the edge is sharp only because it has a defect called a burr. Burrs by themselves can be sharp indeed, but they are thin, irregular, fragile and can bend, roll over, or break off at the root suddenly and unpredictably creating a nasty dull edge in an instant. A truly sharp edge will not just feel sharp, but will stay sharp for a relatively long time because it is properly shaped and well supported, instead of being only temporarily sharp because of an irregular and fragile burr.

I call burrs a “defect” because they are, but creating a burr is an important step in making a sharp edge. The trick is to continue to refine the wedge after the burr is created until the burr melts away on the stones and the edge is as perfect as we can reasonably expect to make it. Stop the refinement work too soon, or fail to do it completely, and all or part of that unreliable burr may survive to plop a floater into your punchbowl.

So how does one tell if an edge is properly sharp and free of deceptive burrs without using a scanning electron microscope?

Do you remember ‘Nando’s philosophy described in my previous post? One must reverse the latin lover’s logic. Don’t rely on mahvelous appearance. Don’t rely on bar room stunts like shaving arm hair or telemarketing tricks like cutting strips of paper. Develop skills and train your senses other than eyesight to detect the shape of steel at the microscopic level. This may sound strange but it is possible because your nerve endings are microscopic and can sense the difference between a burr and a truly sharp edge.

I will save the explanation of detailed techniques for a future post, but for now, here are two essential techniques for sensing things too small to see: Use your fingerprints and the exquisitely fine nerves connected to them to detect the presence and size of burrs; Use your fingernails to check the condition of the burr and determine when the blade is ready to move onto the next stone in the sharpening process. Please don’t cut yourself.

In the meantime, let’s have some pleasure before pain. Prepare to be amazed, Ladies and Germs, because in Part 6, coming soon, The Mystery of Steel will unfold before your very eyes! There will be marble relief carvings, bronze statues, oil paintings, gods and demons, death and destruction, and even a pagan soap opera about forbidden love. Oh my! We’re in negotiations for the movie rights now ♫꒰･‿･๑꒱ and need someone to play Vulcan. If anyone knows Spiderman’s agent, please have his people contact my people right away.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

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The Varieties of Japanese Chisels Part 12 – The Usunomi Paring Chisel (薄鑿)

*24mm Mentori Usunomi by Sukezane (Face View)*

Our thoughts flow to our hands; our tools become as part of our bodies, the blade of our bodies.
Tsunekazu Nishioka, Temple Carpenter, Horyuji Temple Restoration, Nara Japan.

In the first post in this series, we examined the two main categories of Japanese chisels: the tatakinomi designed to be struck with hammer, and the tsukinomi used to pare wood without using a hammer. Beginning with this post we will shift our focus to several varieties of tsukinomi.

If you need to cut precise joints in wood, then you need both striking and paring chisels.

The most popular variety of tsukinomi is the mentori usunomi (面取り薄鑿）which translates to “beveled thin chisel.” The name is appropriate as the blade is long and thin and the neck gently tapered.

*42mm Mentori Usunomi by Sukezane (Side View)*

*42mm Mentori Usunomi by Sukezane (Face View)*

42mm Mentori Usunomi by Sukezane (Ura View)

*24mm Mentori Usunomi by Sukezane (Ura View)*

Description

Just as with oiirenomi, the blades of tsukinomi can be made with different profiles, such as the stiffer rectangular cross-section of the kakuuchi, or the more triangular cross-section of the shinogi usunomi.

The mentori usunomi has a streamlined cross-section similar to the mentori oiirenomi with two bevels ground into the right and left sides of the blade’s face, flowing over the shoulders and feathering into the neck.

An atsunomi or oiirenomi can pare joints, of course, but the steel crown and mushroomed wood fibers on the handle’s end make them uncomfortable for using hours on end.

In comparison, lacking the steel crown and mushroomed handle, the usunomi is more comfortable to use. More importantly, the blades and handles of these chisels are longer and lighter in weight providing superior angular control for precision paring operations.

Western paring chisels by comparison are even thinner and have longer blades than Japanese paring chisels. There can be no denying they do a fine job. But Japanese paring chisels like the usunomi have a few potential advantages worth considering.

The most significant advantage is that the steel cutting edges of Japanese paring chisels are much harder. The paring chisels our blacksmiths forge are around 65~66 HRc in hardness, whereas Western paring chisels are usually around 55 HRc. A Western style paring chisel with its thin blade of uniform steel hardened to 65 HRc would easily snap in half in practical use.

This extra-hard lamination is hand-forged by our blacksmith from Hitachi Metal’s Yasugi Shirogami No.1 steel (aka “White Label Steel”), an exceptionally pure high-carbon steel that makes possible an edge that stays sharper longer, with the result that, given the same number of sharpening opportunities and time in a given workday, a professional-grade usunomi will help you do more hours of high-quality work than a softer blade.

For craftsmen that use their tools to feed their families this higher-level of performance is not something to be sniffed at.

The second advantage of the Japanese paring chisel is their hollow-ground ura which makes it easier to maintain a flat bearing surface, especially important in the case of the hard steel used in our chisels. If you haven’t used Japanese chisels, this claim may sound unlikely. But please recall that there are narrow lands surrounding the ura, all in the same plane, that create a flat bearing surface to guide the chisel.

Usage

This tool is well-suited to reaching into narrow mortises and other wood joints to clean and pare surfaces roughed out by axe, adze, saw and tatakinomi to precise tolerances.

It excels at trimming mortise side walls and end walls. And shaving tenon cheeks and shoulders to precise dimensions without causing spelching or cutting too deeply as shoulder planes are wont to do is a piece of cake.

In addition, the longer blade and flat face of the usunomi make it ideal for paring angles, such a 45° mitres, in combination with wooden guide blocks or jigs.

The usunomi may be struck with the heel of the hand, but never with a hammer or mallet. The slender neck, thin blade, and un-reinforced handle will simply not accept such abuse gracefully.

Chisels intended to be struck with a hammer typically perform best with a cutting edge bevel of 27~30°. Any shallower and the hard steel at the cutting edge may chip instantly dulling the tool. However, the cutting edges of usunomi along with other tsukinomi are not normally subjected to the high stresses chisels motivated with hammers must endure, so the cutting efficiency can be increased by lowering the angle to 24° or so without creating problems, depending of course, on nature of the wood you need to pare and the type of paring you intend. For instance, paring end the grain of maple may require a steeper angle than when paring the long grain of pine.

If you have used long-bladed Western chisels hard for a few years, you will have no doubt experienced your chisel’s flat becoming somewhat rounded over after many sharpenings. This occurs because, for various reasons, the center portion of the blade’s flat is abraded at a slower rate when being sharpened than the blade’s perimeter, resulting in distortion regardless of whether you keep your stones perfectly flat or not.

Obviously, a chisel with a flat that is banana-shaped lengthwise and crosswise is not ideal for paring flat surfaces, but there is a bigger problem. Namely, it is simply more difficult and time-consuming to create a sharp edge on a blade with a curved flat than one with a true flat. A flat like this begs for amateurish tricks using rulers, etc.. of the sort professionals would be embarrassed to use. A friend once scathingly described these techniques as “training wheels.” Oh my.

The ura on the Japanese chisel is specifically designed to deal with this shortcoming, and it does a great job of it.

30mm Unsunomi by Nagamitsu – View of Mitsuura

30mm Unsunomi by Nagamitsu – View of Face

*30mm Unsunomi by Nagamitsu* – Closeup of Mitsuura

The 30mm usunomi in the photo above has an ura with three hollow-ground areas instead of one. This detail is called a ” mitsuura” ミツ浦 meaning ”triple ura.” It has the advantage of providing a larger bearing surface than the standard ura does, one that is helpful when used with wooden jigs for paring to precise angles, for instance. It also helps the ura index better when paring large surfaces, especially with chisel blades wider than 24mm.

Some people prefer chisels with the mitsuura detail for their appearance. I admit mitsuura look sexy, but I am not a fan of using this detail unless it is truly necessary because of the downsides I will not deal with in this already overlong post.

If I can liken the atsunomi to a shire horse, then the usunomi is a falcon. Both are beautiful powerful animals, but just as one wouldn’t use a draught horse to chase down a rabbit, or a peregrine to pull a plow, neither oiirenomi nor atsunomi are as effective as the usunomi for paring and cleaning joints.

A Shire Horse and His Little Friend. Stout, heavy and strong is good for some jobs, but…

Slim, light, fast and sharp is better for others.

The usunomi is one of those tools that is a pleasure to use.

Among woodworking tools, the usunomi is special: as it becomes part of your hand, you will discover that neither the blade nor your hand but your mind is shaping the wood.

YMHOS

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Sharpening Part 4 – ‘Nando and the Sword Sharpener

And this is from my heart
Which is deep inside my body:
It’s better to look good
Than to feel good
Fernando

This article is a little longer and more roundabout than your most humble and obedient servant’s previous posts, but I wanted to share with you some of Japan’s history, and examples of this country’s most fabulous practical art as produced by its blacksmiths and professional sharpeners as insight into the Japanese mindset regarding sharpening. But before I get into that, I would like to share some relevant words of wisdom from Hollywood’s wisest man.

The handsome gentleman in the picture above is Fernando (actually Billy Crystal). He is neither a blacksmith nor a sharpener of tools or weapons, but his insight into physical beauty and words of wisdom about happiness are pertinent to sharpening, as we shall see below. If you are not familiar with ‘Nando, I suggest you google him or view a video or two on NoobTube.

So what does this dapper Latin lover have to do with sharpening? And swords?

As ‘Nando taught the world, a wise person will not equate looking good with feeling good. Likewise, you would be wise to not confuse a blade’s appearance with its performance. Indeed, a blade that looks as sharp as the skinny end of nothing may not actually cut well in some applications. A good example is Japanese swords. Let me tell you a true story to illustrate my point.

When I was a university student in Japan, I was privileged to be entrusted with a number of swords that belonged at the time to the late Dr. Walter Compton, Chairman of Miles Laboratories and the inventor of Alka-Seltzer. He was a wealthy man who had a huge collection of swords obtained while an officer for the US military in Japan immediately after the war when Allied forces required the defeated Japanese people, on pain of death, to surrender all swords, civilian and military. Of course, many valuable and rare family heirlooms were surrendered or forcefully confiscated. Supposedly they all went to the bottom of Tokyo Bay in bunches, or were melted for scrap. But we know better, don’t we.

Towards the end of his life, Dr. Compton put a lot of money into having his better swords professionally sharpened, new shirasaya scabbards and furniture made, and formally evaluated in preparation for donating them to the Boston Museum of Art, where many of them reside in obscurity today. Sadly, due to progressive dementia, some of his most valuable swords were auctioned off without his permission. “The feckless sons of wealthy men” is the operative phrase in this case, I fear.

I assisted Dr. Compton’s representative by transporting over 70 of these swords to and from Japan and performing the necessary legwork to accomplish these goals inside Japan. During those years I held in my hands and feasted my eyes on rare and beautiful blades of great historical value several of which would have easily been designated National Treasures if they had been intended to remain in Japan (“National Treasures” may not leave Japan).

During those years I spent a lot of time meeting, questioning, and requesting services of the best sword sharpeners in Japan, and learned a lot about swords, stones, and sharpening. Dr. Compton’s reputation was such, and his swords were of such rarity and high quality, that I had no difficulty persuading the very best craftsmen to work on them and speak with me, including a famous sword polisher named Mr. Okisato Fujishiro.

Interestingly, in Japan such craftsmen are called “Togishi” (研師), an unambiguous word that can only be translated as “sharpener.” However, in the West these same Japanese craftsmen are called “ Sword Polishers.” In the post-war context, this actually may be more accurate than the Japanese term. In a post-war world it’s certainly more politic.

A very subtle, high quality sword tip brought to life by the arts of the Sword Sharpener. Notice the peaceful elegant hamon *(wavy milky pattern at the cutting edge oriented towards the top of the photograph)*, the grain of the steel just below the hamon, and the burnished polish surrounding the fuller. Notice also the clean delineation where the blade tip, the “boshi,” begins. Very nice work.

Before the elimination of the caste system Japanese society had 4 main divisions labeled “Shi No Ko Sho,” meaning, in descending order, Warrior (samurai), Farmer, Craftsman, and Merchant at the bottom. The Emperor, Court Nobles, and Shoguns were above these strata, although of the three, only the Shogun possessed any actual power because the man with the sword makes the rules, and those without weapons do as they are told and quickly, or they go away permanently. Thus it has always been because both fool and wise man leak red sticky stuff.

Blacksmiths and sword sharpeners were both in the craftsman caste, but curiously the sword sharpener was above the swordsmith in rank. Depending on their support among the warrior caste, and with the generous application of yellow metallic lubricant, both swordsmiths and sword sharpeners occasionally obtained noble rank, an honor to which few craftsmen, farmers, and merchants could aspire. My point is that sword sharpeners, while of relatively lower caste, often had a perceived rank higher than their craftsman position would suggest.

Why was the Japanese sword sharpener of higher rank than the swordsmith? I haven’t seen documentation from back in the day confirming it, but I suspect it is because the sharpener turns the swordsmith’s plain steel blade into a thing of jewel-like sculptural beauty that almost seems alive. One only has to see a sword blade fresh from the swordsmith’s shop and compare it with the same sword after the sharpener’s ministrations to understand.

The Nikko Sukezane sword, a designated National Treasure of Japan

å¤§è¬è¥é·å-ç»å2 — This sword is another of Japan’s National Treasures. It was forged by a swordsmith name Nagamitsu (長光）during the same time period as the Sukezane above. The tang (nakago) is corroded by exposure to bare hands over a period of around 700 years. Multiple holes were drilled in the tang to accommodate a variety of hilts during its lifetime. I also had a sword by this same smith and of very similar appearance in my care for about one year, although it was not owned by Dr. Compton.

A different Nagamitsu sword, also listed as a National Treasure. An unusually healthy example.

I have even witnessed a skilled sword sharpener create a beautiful hamon (a pattern formed on the edge of a sword by the steel’s crystalline structure) on a sword forged by a famous smith that had lost the crystalline structure necessary to form an actual hamon. While a deception of sorts, the intention was not to deceive for profit (the sword was donated to a museum), but to return an unusual and historically important sword to its former beauty, a glory that would have been lost but for the sword polisher’s exceptional skills.

A dramatic chouji midare hamon in a modern sword. The pattern exists not because of a lamination or some silly pattern welding but because of the changing crystalline structure of the blade that results from the differential heat treatment process performed by the blacksmith. It only exists because of the swordsmith’s skill, but it is only visible and beautiful because of the sword sharpener’s stones and his skill with them. Is the blade sharp? Don’t judge a blade’s performance by its polish.

If we liken the swordsmith with his forge and hammer to the quarry worker cutting marble from the mountain, then the sword sharpener is Michelangelo cutting the Pietà with his chisels and files. Both craftsmen work on the marble and blade respectively, and both are essential. The sculptor uses steel to bring stone to life, while the sword sharpener uses stone to bring steel to life.

Another dramatic hamon in a modern sword. This pattern is a surface manifestation of the steel’s crystalline structure as created by the swordsmith, but revealed and made glorious by the polisher

But despite these artistic abilities, modern “Sword Polishers” have no interest in and put forth no effort to actually make a sword blade cut well. Indeed, in some cases, they actually intentionally dull the blade so it can’t cut, thereby making it safer. This intentional vandalism is called “habiki.”

A different style of hamon pattern on a blade with a different grain pattern. Notice the different colors and lines inside the hamon. All these crystalline details are categorized, have names, and are studied intensely by aficionados. All things equal, this sort of pattern and color is considered to be more elegant and desirable than the two more dramatic hamon pictured above. An extremely deep rabbit hole, I assure you. Please watch your step!

Here’s the key point your humble servant wants Beloved Customer or Gentle Reader to grasp: Despite the long years of apprenticeship, advanced skills learned, and gallons of red sticky stuff unintentionally leaked by sword sharpeners, the frank sword sharpeners I have spoken with all admitted that, of all the craftsmen in Japan that used edged tools, woodworkers like carpenters, cabinetmakers, and joiners routinely create sharper blades despite those blades not appearing to be as sharp as swords. This is consistent with my direct experience of handling over 70 swords before and after being worked on by sword sharpeners.

While there is great pleasure to be found in polishing a plane or chisel or knife blade to levels of great beauty, do not make the mistake of equating appearance with performance.

Appearance aside, and looking strictly at cutting performance, will a chisel or plane or knife blade skillfully sharpened on a 15,000 grit stone cut better and longer than if sharpened on an 8,000 grit stone? In the case of woodworking blades and kitchen knives, no it won’t. In fact, due to higher levels of friction the higher degree of polish produces in the cut, it will certainly not cut wood as well. More on this subject later.

An oiirenomi by Hidarino Ichihiro Oiirenomi. The hazy silver of the hard steel hagane lamination and the cloudy grey of the softer iron jigane lamination, combined with the shape and upward curvature of the corners of the lamination are indicative of excellent craftsmanship by the blacksmith, superior skills of the sharpener, and wonderful stones. Such details are considered sublimely beautiful to tool connoisseurs. But will the edge cut well? We can’t tell from this photo.

Keep in mind that the stones used to apply the beautiful polish and accentuate the hamon on Japanese swords are different from those used to sharpen woodworking tools. For instance, the uchigumori stones sword polishers use are small slices of soft stone glued to paper using urushi lacquer adhesive, and are only 3,000~5,000 grit. These small slips of stone are rubbed on the sword blade using thumb and fingertips.

Here is a link to a blog showing Mr. Fujishiro, son of one of the sword sharpeners I employed back in the day, making and using these thin slices of stone.

Tools are designed to perform specific tasks. Although it could do the job, more or less, you wouldn’t use a crescent wrench to stir spaghetti sauce on the stovetop would you? A longish spoon just might work better.

Does a sword’s edge need to be extremely sharp to cut the enemy effectively? No, it doesn’t because the sword’s speed, impact force, and the swordman’s technique drive its cutting effectiveness much more than simple sharpness. So sword sharpeners in Japan, and probably most of the world too, have always been more focused on edge durability, resistance to chipping, and appearance than absolute sharpness. In modern times, when swords are almost never used to cut living flesh outside of Saudi Arabia, the blade’s appearance may be critical, but sharpness is not a practical concern.

Another example is food preparation knives. A chef’s knife looks terribly sharp, and as it slices tomatoes and fillets fish we can see that it cuts well. But how sharp is it really? In comparison with a joiner’s plane blade, not really that sharp. But both tools are exactly suited to the job assigned them.

æ³ååä¸(åºèº«åä¸) — The sashimi knive’s blade is made long and thin to facilitate draw-strokes that cut the fish cleanly. The chef applies little downward force during the cut because excess pressure would rupture, rather than cut, the cells ruining the flavor of the tuna sashimi. Yes indeed, a properly sharpened knife and expert technique make a difference in flavor, just another reason why the Japanese are obsessed with sharp things.

The chef’s knife is most effectively used in slicing or drawing motions, much as expert swordsmen use their weapons against enemies. In this style of cut, a smooth and uniform cutting edge does not perform as well as a more ragged, serrated edge as seen at the microscopic level. Therefore, there is little if any practical benefit (assuming beauty is not practical) to be obtained by sharpening a kitchen knife beyond 1,000~3,000 grit. In fact, at least in Japan, these are the upper-limit of stones in daily use by professional chefs of all varieties. Yes, and that includes sushi chefs.

But don’t misunderstand my point: In the case of both swords and yanagiba hocho knives, the bevel angle must be correct for both the blade being used and the material being cut, and the microscopic edge must be a clean intersection of planes. If you get these two factors wrong, a crescent wrench might work just as well.

The other point I want to make is that, while I enjoy using high-level skills to give a beautiful appearance to extremely sharp blades, such a blade will not perform better than an identical blade of equal sharpness but with a less polished appearance, and the extra time and money spent on improving outward appearance is wasted on bread and butter work.

Since Hollywood celebrities have the answers to all the world’s problems (at the cost of other people’s money, labor and freedom, of course) perhaps our quest for the sharp edge can benefit from the wisdom of the famous Latin lover ‘Nando, Tinseltown’s most elegant star. ‘Nando once shared his father’s advice that it is “better to look good than to feel good.” Accordingly, perhaps we should all go crazy nuts and polish our blades like beautiful but dull museum swords and wear waistcoats and cravats as we cut sliding dovetails and plane door stiles. After all, one must be ready for every photo op. In this way, our woodworking blades may be worthy of ‘Nando’s highest praise: “You, dahling, you look mahvelous, absolutely mahvelous.”

Fernando Lamas in “*The Merry Widow.”* The crease in his pant leg could slice bacon.

No, on second thought, while there is much one can learn from Fernando’s elegant philosophy, his standards of beauty and suffering are too high for me. I would rather be a simple joiner or cabinetmaker in stained work clothes that has the ability to make a blade exceptionally beautiful but chooses not to expend the time and cost required to do so most of the time, rather than someone who doesn’t because they can’t.

Although Fernando has a pressing appointment for a tango lesson (discretion prevents me from naming the young lady he will be pressing) and won’t be providing further insight today, our adventures in sharpening Japanese woodworking tools will continue in Part 5 of this series.

Let’s meet at Tsukiji for sushi afterwards.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Sharpening Part 3 – Philosophy

“A wild boar was sharpening his tusks upon the trunk of a tree in the forest when a fox came by and asked, Why are you doing that, pray? The huntsmen are not out today and there are no other dangers at hand that I can see. True, my friend, replied the Boar, but the instant my life is in danger, I shall need to use my tusks. There will be no time to sharpen them then.”
Aesop (621~565 BC)

It’s nice to have a philosophy on a subject because it helps one distill random thoughts down to the essentials.

Allow your humble servant to explain his philosophy about sharpening woodworking tools, not because it is charming and unique, and not because you should emulate it, but because it will provide insight into the things written in this blog and elsewhere. Use it to calibrate your BS meter. It is often neck-deep when people talk about sharpening.

My philosophy regarding sharpening was shaped by my experience as a carpenter, contractor, commercial cabinetmaker, and joiner working under pressure, against a clock, sometimes with a boss watching with eagle eye, and often in front of customers, not as a hobbyist fiddling around in a garage workshop. Married young with a growing family to support, I quickly discovered that children eat constantly and in ever-increasing quantities, so efficiency was and is important to me.

Efficiency was also important to the Clients who hired me. Sharpening and maintaining tools is, of course, part of the job, but from the Client’s viewpoint, it’s wasted time, so it’s important to minimize time spent fiddling with tools during the work day. Accordingly, I followed the example of craftsmen I respected and started the day with sharp tools in good working order, and kept spare planes and chisels sharpened and ready to go as backup.

Self-employment hammered into me the monetary value of time. It also taught me that quality sharpening stones and tools are expensive and wear out, and that to feed wife and babies every day I had to work efficiently to minimize time and money expended on maintaining tools, while maximizing the amount of work I accomplished between sharpening sessions.

I developed a strong dislike, nay hatred, for blades that fail to perform, refuse to become extremely sharp, dull quickly, or take too much time and effort to sharpen. I loathe them not just because they are irritating, but because they waste my time and money. Even considering the higher initial cash outlay, the cost-effectiveness of handmade, professional-grade tools in helping my mind and hands do good work and feed the family became as obvious as a burning road flare on a midnight highway.

You, Beloved Customer, may not feel the time and financial pressures that professionals do, but owning professional-grade cutting tools and learning how to sharpen them in an efficient and professional manner will make woodworking less frustrating, more profitable, and more enjoyable.

What is your philosophy?

The journey will continue in Part 4 with wisdom from a celebrity and pictures of pretty swords. Until then, I have the honor of remaining,

YMHOS

Sharpening a plane blade at the jobsite, then back to work, jiggity-jog.

YMHOS

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Links to Other Posts in the “Sharpening” Series

Sharpening Part 2 – The Journey

You don’t have a soul, Doctor. You are a soul. You have a body, temporarily.”
Walter M. Miller Jr., A Canticle for Leibowitz

Life is neither a dead-end course nor a race, but a hard journey along many paths all leading to a single gateway. What matters are the friends and family that journey with us, the kind deeds we do, the joy we share, the things we experience and learn along the way, and most importantly, the quality of our souls at the journey’s end, for these are all that will pass through that last gateway into eternity with us; Nothing else matters a hill of beans.

Woodworking can be a wonderful diversion and even a source of joy during this journey, one that can make our lives and the lives of those around us more pleasant. For many it is a way to keep body and soul connected. For those that rely on their tools to feed their families, the efficiency of that work, and the joy they find in doing it are not trivial matters.

Thoughtful woodworkers on this path learn early that dull tools are an impediment to making excellent wooden products regardless of the skill of the hand and eye that manipulates them, because, being an extension of the user’s mind and hands, a dull tool will often darken the mind and leaden the hand of even an accomplished woodworker.

Sharpening has always been the most important woodworking skill. It is no coincidence that for millennia the first thing apprentices were taught once they were permitted to handle valuable tools was how to sharpen them properly.

In our time the prevalence of machinery with built-in precision and blades driven by motors and sharpened by others has made it possible for those lacking even basic sharpening skills to represent themselves as craftsmen. Although they may be skilled, I believe such individuals are less craftsmen in wood and more machinery operators.

Those thoughtful souls who aspire to become accomplished woodworkers, and not just machine operators, need minimal sharpening skills. Untold thousands of years of human history verify the truth that all other woodworking accomplishments flow from this bedrock skill.

I believe, perhaps because the men I learned from and respected also believed, that free-hand sharpening is the way a skilled craftsman maintains his tools. My experience and observations over many years have confirmed the efficiency of this technique. It is consistent with my work-driven philosophy about sharpening which I will explain in more detail in the next post in this series.

Sharpening a blade free-hand is a zen-like activity. It requires observation. It requires muscle memory. It requires consistency. It requires composure. It requires meditative focus. And at the pinnacle, it requires one to feel and hear work being done in a place one cannot see, a place where destruction creates order; where nothing becomes something.

Some will disagree with my beliefs about free-hand sharpening, especially the machinist-types, the scribblers and gurus promising instant results in a few hours for the price of a book, DVD, or class, and the purveyors of sharpening jigs disinclined to work without “training wheels.” No mystery there. So I won’t even try to please everyone, just professional woodworkers.

When professional woodworkers gather in the presence of edged tools, they often talk about sharpening techniques and rare stones, and they are always curious about the quality of other men’s tools. In Japan, it is considered rude to pick up another’s tools and examine the edges, or even to look at them too hard, but the desire is always there nonetheless because it is human nature to compare oneself to one’s peers.

Indeed, much can be learned about a man’s quality standards and his skills from his blades. Perhaps the condition of one’s tools gives a tiny glimpse into the owner’s character.

What do your tools say about you? Some are terrible gossips, you know. (ツ)

The journey will continue in Part 3 with wisdom from a celebrity and pictures of pretty swords.

Allow me to end this article with a quote from the best-selling book of fiction in human history:

End? No, the journey doesn't end here. Death is just another path. One that we all must take. J.R.R. Tolkien, The Return of the King

YMHOS

Tianmen Gate, China. 999 steps to the natural gateway above.

If you have questions or would like to learn more about our tools, please click the “Pricelist” link here or at the top of the page and use the “Contact Us” form located immediately below.

Tag: Sharpening

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Laminated Bi-Metal Construction

Laminated Blades in the West

U-Channel Construction

The Ura

The Point

Conclusion

Links to Other Posts in the “Sharpening” Series

Sharpening Part 7 – The Alchemy of Hard Steel 鋼の錬金術

The Alchemy of Mutating Iron to Steel

Impurities and Alloys

Japanese Steels

The Challenges of Working Plain High-Carbon Steel

Links to Other Posts in the “Sharpening” Series

Relevant Posts

Sharpening Part 6 – The Mystery of Steel

Steel Magic

Vulcan the God

Wayland the Smith

The Blacksmith’s Shop

The Japanese Smithy

Links to Other Posts in the “Sharpening” Series

Relevant Posts

Sharpening Part 5 – The Sharp Edge

The Basics

Wood Shaving’s Eye View

Edge Failure

Links to Other Posts in the “Sharpening” Series

Other Relevant Posts

The Varieties of Japanese Chisels Part 12 – The Usunomi Paring Chisel (薄鑿)

Description

Usage

Links to Other Posts in this Series

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Links to Other Posts in the “Sharpening” Series

Sharpening Part 3 – Philosophy

Links to Other Posts in the “Sharpening” Series

Sharpening Part 2 – The Journey

Links to Other Posts in the “Sharpening” Series

Laminated Bi-Metal Construction

Laminated Blades in the West

U-Channel Construction

The Ura

The Point

Conclusion

Links to Other Posts in the “Sharpening” Series

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The Alchemy of Mutating Iron to Steel

Impurities and Alloys

Japanese Steels

The Challenges of Working Plain High-Carbon Steel

Links to Other Posts in the “Sharpening” Series

Relevant Posts

Share this:

Like this:

Steel Magic

Vulcan the God

Wayland the Smith

The Blacksmith’s Shop

The Japanese Smithy

Links to Other Posts in the “Sharpening” Series

Relevant Posts

Share this:

Like this:

The Basics

Wood Shaving’s Eye View

Edge Failure

Links to Other Posts in the “Sharpening” Series

Other Relevant Posts

Share this:

Like this:

Description

Usage

Links to Other Posts in this Series

Share this:

Like this:

Links to Other Posts in the “Sharpening” Series

Share this:

Like this:

Links to Other Posts in the “Sharpening” Series

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Links to Other Posts in the “Sharpening” Series

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