The Japanese Sumitsubo Inkpot 墨壺: Part 3: The Modern Sumitsubo

The newest Cylon-inspired modern sumitsubo by Shinwa

The way of the carpenter is to become proficient in the use of his tools; First to lay his plans with true measure and then perform his work according to plan. Thus he passes through life

Miyamoto Mushashi – Go Rin no Sho

In the previous article in our series about the Sumitsubo, we examined some traditional wooden examples, and a plastic version of the same.

In this edition we will take a look at the modern version sold in hardware stores around Japan.

In the previous article your humble servant mentioned that this style of sumitsubo appears to have been designed by Cylons, the chrome-plated red-eyed nemesis of the Battlestar Galactica and her brave crew. Gentle Readers must decided for themselves whether or not alien machine lifeforms from a far galaxy were engaged in the design process or not, but I have no doubts on the matter (シ).

The Design Concept

These modern sumitsubo function much the same as traditional wooden sumitsubo in that a line, stored on a reel, is spooled out through a reservoir containing absorbent material soaked with ink, becoming partially saturated with ink. The wet line is then secured to the material to be marked at one end using a “karuko” bob with a needle. At the opposite end of the material, the line is aligned with another mark, tensioned, lifted up and released snapping against the material and leaving behind a line of ink.

Besides the intergalactic alien design influence, the most obvious difference between these modern sumitsubo and the traditional ones is that the line, the reel, and the ink reservoir are entirely enclosed in a cleverly-designed, tough and lightweight plastic housing which not only keeps the ink from drying as quickly, but permits the tool to be dropped into a tool bag or toolbox without risk of getting black ink all over everything. Much more convenient.

The ink reservoir is concealed under a little plastic hinged door that one opens to add ink to little sponges. In the better sumitsubo this reservoir has rubber seals and special slits to prevent ink from leaking. This combination of sponges and seals works quite well so long as one doesn’t add too much ink. But everyone does this at least once…

In the case of automatic sumitsubo, as are the examples shown, a coil spring enclosed in the reel mechanism automatically spools the line back onto the reel in preparation for the next snap. Some versions lack this spring and must be rewound by rotating the reel using one’s fingertips.

Please note that this spring action, while quick and convenient, is not 100% blue bunnies and fairy farts because the karuko’s sharp little point can give the user a serious boo boo if control is lost. To prevent embarrassing injuries (i.e. leaky eyeball syndrome), the karuko sold with most of these sumitsubo are designed to automatically retract the needle safely into a plastic housing when released.

As someone who has unintentionally initiated one or two haphazard tattoo patterns on hand and arm over the years with flying karuko needles, your humble servant highly recommends Gentle Readers “stick” with these retractable needles. And don’t forget your safety glasses.

Changing the line of the modern sumitsubo is much easier than with traditional sumitsubo because there are no holes to thread the line through. All that’s necessary to change a line is to open the ink reservoir, remove the reel, tie the new line to the reel and karuko, replace the reel, lay the line through the reservoir, and close the lid. Eazy peazy japaneazy.

Gentle Reader may recall from the previous article that, when using the traditional sumitsubo, one must simultaneously press down on both the line and wadding in the ink well with a bamboo sumisashi as the line is spooled out to ensure an adequate amount of ink soaks into the line. This is not possible in the modern sumitsubo with its covered ink reservoir, so instead, one pushes down on a rubber button while spooling out the line to achieve the same results. This rubber button in turn presses down on the line and sponges transferring ink to the line.

Major Brands of Modern Sumitsubo Available Today

There are two major brands of sumitsubo on the market in Japan today: Shinwa of steel square fame and Tajima best known for its tape measures.

Two of both brand’s most popular models, in various states of undress, are shown below.

When it comes to sumitsubo, Shinwa is the older and more experienced of the two, but Tajima has more eye-catching products and a powerful marketing department with a nation-wide distribution network.

A side view of the Shinwa Sharp-line sumitsubo with extra-fine line. The design looks much like a space ship with a non-slip grip. Phasers and proton torpedoes are currently not available options for this model. Maybe next year.
The Shinwa Sumitsubo with its lid open. Yellow sponges to contain ink are mounted in the lid and body. A blue rubber seal installed in the lid seals the ink reservoir to prevent leakage and reduce evaporation. Although not visible in this photo (see the photo at the top of this article) the sponges and line can be squeezed together by pressing on a rectangular rubber button in the lid. The stainless steel pin visible to the left of the reservoir guides the line and keeps it from abrading the plastic. A stainless steel ring at the sumitsubo’s mouth (far right) guides the line and keeps it from abrading the body too. The needle in the karuko is spring-loaded so if left on its own it retracts into the karuko’s plastic body, but in this photo it is held extended with tape. The karuko has a rubber “O” ring of sorts molded to its end that fits tightly into the body’s mouth to prevent leakage. The Tajima Sumitsubo lacks this detail. At the far right end of the lid a black operable metal tab can be seen extending from the body. This helpful widget is used to precisely locate and press down on the line before the snap. This too is not found in the Tajima version. At the far left can be seen a loop for attaching the tool to the toolbelt or safety harness with a lanyard as required by Japan’s safety regulations when performing overhead work. Beam me up, Scotty.
The newest Shinwa sumitsubo disassembled, a three second operation accomplished without tools. The body with the lid to the ink reservoir and its sponges and rubber seals is open in the center. The reel is upper left. The circular casing that secures the reel within the body and contains the brake and drag, features also not available from Tajima, is lower left. The karuko with its spring-retracted needle extended with tape is located center right. Liquid ink is dripped onto the sponges and the lid is closed locking the reel and line in-place. A coil spring inside the reel assembly spools line back onto the reel automatically.
The Tajima version of the modern sumitsubo. It has a slightly more organic shape reminiscent of a gourd, a traditional motif in Japan. The narrow waist in both the Tajima and Shinwa models ensures a comfortable one-handed grip in the field. This sumitsubo has a round rubber button located to the right of the word “EVO” to actuate pressure on sponges and line.
A side-view of the Tajima sumitsubo showing the lid’s hinges. The karuko is inserted into the mouth in this photo, and is larger than the Shinwa’s karuko.
The disassembled Tajima Sumitsubo. It has two blue sponges mounted inside the body, instead of Shinwa’s yellow sponges, one of which is mounted in the lid. Accordingly, the underside of the more complicated circular rubber pressure mechanism can be seen in the open lid. A black rubber seal mounted in the lid keeps ink from leaking from the reservoir (at least that’s the idea). Unlike the Shinwa, the line must be thread through the mouth without the karuko attached, a little less convenient. This sumitsubo has two stainless steel pins guiding the line to and from the reel, although I’m not sure why two are necessary. It too has a stainless steel ring at the mouth to limit wear, but it can’t be seen from this angle. In addition, a hard, wear-resistant plastic block is inserted where the line exits the reservoir to the right to reduce wear. The reel is held in place by the plastic ring bottom left, which is twisted then locked into place when the reservoir’s lid is closed. This tool comes in various sizes and colors and is probably the most popular sumitsubo commercially available in Japan today.

Your humble servant, being gleefully addicted to trying out new tools, owns both brands of sumitsubo. Perhaps I need a 12-step program and a good detox to mitigate my tool-based delirium tremens? In any case, I’m convinced Shinwa products are perhaps a little superior in performance, but the Tajima sumitsubo are undeniably good too.

As I wandered around a construction project in Chiba Prefecture I’m in charge of last week I paid attention to the sumitsubo workers were using and observed that Tajima products were in greater evidence. Not a scientific study by any means, but more accurate than the flyblown tripe the hopelessly corrupt World Health Organization calls science lately.

A few weeks ago I visited a local hardware store I do business with regularly. Although it’s not the first or even the second building that has housed this business at this same location in Suginami Ward in Tokyo, the family that owns it has been selling tools and building hardware to contractors and professional craftsmen for over 100 years. Inside it has tools and building supplies literally stacked to the ceiling, much of which is cantilevered precipitously over the narrow, crowded aisles between steel shelves to the point where entering the store and moving around is not a simple task. A death trap should an earthquake strike, I fear.

The current owner is 90+YO with a warm smile and honest habits who is easy to trust. I asked him which sumitsubo products are most popular among his professional customers. His answer was that they seem to buy the Tajima products more, although he couldn’t give a single reason why. I suspect the fact his shelves are full of Tajima products with nary a Shinwa product in-sight has something to do with their selections.

Tajima’s distribution network is hard to beat.

My old ten-year old Shinwa sumitsubo. It’s currently setup for construction jobsite use with heavier line and a karuko with both a needle and super-magnet base for use with structural steel and LGS studs. The reservoir lid’s hinge is half broken, but still works good enough. I purchased the Cylon blue Shinwa sumitsubo dissected above as a replacement in anticipation of its imminent retirement.

Inklines

The lines used in sumitsubo were once all made from either hemp or silk fibers, I’m told. Nowadays, hemp can’t be had for love or money, but silk is still available. Modern fibers made from polyester and nylon are most prevalent of late. Better lines contain kevlar or spectra fibers for extra strength.

I am fond of thin (>0.4mm) lines for cabinetwork because they make cleaner marks, but skinnier lines are less durable and the marks they leave are less visible from a distance and on rough surfaces, so for construction projects, although 1.0~1.5mm lines can be purchased, 0.6~0.8mm lines are what most people use.

Conclusions

I am fond of the simple, elegant, antique appearance of the ichimonji-style wooden sumitsubo.

A carpenter-made ichimonji-style sumitsubo in the workshop. We share the same ebony karuko

I have used the more modern Genji-style wooden sumitsubo for many years, and like them enough to have one mounted inside my toolchest for good luck. Like many older craftsmen, I appreciate the appearance of a tool beautifully hand-carved from attractively figured colorful wood, and think the traditional wooden sumitsubo feels better in the hand and adds dignity to the work.

But the modern Cylon-designed plastic sumitsubo is cheaper, tougher, and much more convenient, which is why I reach for one when I need to snap a line. Who was it that sang: “The times they are a-changin?”

Which style do you prefer?

YMHOS

To pixies that stray too near, the little turtle gives his best Lee Van Cleef glare and growls: “Stay away, vile creatures, or I’ll bite you in two, snicker-snak!” He is most persuasive.

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.

Please share your insights and comments with all Gentle Readers using the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, thuggish Twitter, nor a US Senator’s Chinese girlfriend and so won’t sell, share, or profitably “misplace” your information. May my karuko ravage my family jewels if I lie.

Other Posts in Japanese Sumitsubo Inkpot Series

The Marking Knife

A spearpoint marking knife

“Make sure that you always have the right tools for the job. It’s no use trying to eat a steak with a teaspoon and a straw.” 

Anthony T. Hincks

There are many varieties of marking knives used for woodworking around the world. In this article your humble servant would like to discuss the Japanese version.

We will begin with some definitions, followed by an explanation of the design details and structure of the tool. We will save the best for last by describing two subtle but effective professional modifications to improve the tool’s performance and the results produced.

Definitions

The Japanese marking knife is called a “shiragaki” or sometimes “shirabiki.” The characters used vary, but can mean “white pull” (白引き), which makes some sense, or “white persimmon” (白柿), which makes little sense, so I suppose the persimmon character is used as a phonetic substitute for “kaki” (書き) which means to write. I choose to write the word as 白書 so the Kanji translate directly to “white writing.” That makes more sense to me.

Such confusing substitutions are all too common in the Japanese language in the case of words with purely phonetic origins. The fact is that, much like psychologists, lawyers, and priests, the Japanese people enjoy confusing terminology. It’s an ancient habit that probably won’t change soon. I say this as someone that has been reading, writing and speaking the Japanese language at graduate school level for 45 years, been a resident of, attended school and worked in Japan for 30 years, and been married to a Japanese woman and had Japanese relatives for 43 years. I can get into serious trouble in the Japanese language.

Now that we are done with the Japanese language lesson, I will simply call this tool a “marking knife.”

The marking knife is used to cut thin, precise layout lines in a board’s surface, most often but not always at a 90 ° angle to the direction of the wood grain.

Every woodworking tradition I am aware of includes the marking knife, and regardless of their preferred style, anyone serious about woodworking will own at least one, and know how to use it.

Advantages

The marking knife has some advantages over other methods of marking a line more-or-less perpendicular to the direction of the wood grain. Here are a few:

  1. The line it makes can be as thin as the edge of nothing, achieving precision unapproachable by pencils, pens, scribes, sumisashi, inklines, chalklines, laser-sights, or even wishful thinking for layout in wood in the case of lines at more-or-less 90˚ to the direction of the grain. The line it makes, however, is not as easy to see as an ink or even pencil line, so it is not always useful for rough layout work;
  2. The line cut by a marking knife penetrates the wood’s surface providing a physical place into which the woodworker can index the edge of his chisel, or nicker of his plow plane or rabbet plane, or the teeth of his saw, or points of his divider quickly, precisely and confidently without relying heavily on Mark-1 Eyeball, improving the efficiency and quality of both his layout and fabrication efforts. The resulting time savings, improvement in accuracy, and reduction of eye strain the indexing benefits marking knife lines provide are huge.
  3. When making layout lines on perpendicular faces of a member, such as a table apron, for instance, after making one line on the reference face, the remaining three lines can be indexed and extended from each other with a marking knife, confirming the accuracy of the member’s dimensions and ensuring the tenon shoulders will be sawed accurately creating an excellent tenon, assuming the craftsman knows how to use a saw properly, of course.
  4. The line cut by a marking knife severs the fibers near the board’s surface helping to prevent fibers from being torn out of the wood avoiding a ragged cut with saw, chisel or router.

Are you convinced yet?

Design & Materials

Shirabiki Ura by Konobu

There are many styles of marking knives used around the world, and your humble servant has tried most of them at one time or another, but none that I am aware of are as simple as, or functionally superior to, the Japanese version.

Lacking a pretty, turned handle and looking more like a blackened steel popsicle stick than a finished tool, the Japanese marking knife appears unfinished, even barbaric. But despite its stark appearance, it’s a sophisticated design that employs superior metallurgical and blacksmithing techniques.

Like many Japanese woodworking tools, the professional-grade marking knife is made with a layer of hard high-carbon steel forming the cutting edge, forge-welded to a softer layer of low-carbon steel which forms the body of the tool. They are almost always flat, generally thin, and not especially wide tools. Perhaps 1/2 the length of one side is ground flat and bright and includes a hollow-ground depression called the “ura,” while the other side is plain and includes the cutting edge’s bevel.

Some marking knives, such as the photo at the top of this article, have a spear point or “kensaki” (剣先)meaning “sword point” which is convenient because the same knife can be used either left-handed or right-handed. Some people prefer this style, but in my experience it has limited usefulness. To each his own.

The demands on the marking knife in terms of sharpness, durability, and edge-holding capability are not as high as for chisel and plane blades. The better-quality ones are hand-forged of high-carbon steel and quality jigane, properly shaped and filed, and carefully heat-treated.

Because of their thinness, marking knives tend to warp badly during heat treat, and consequently demand either a blacksmith with good skills or the use of high-alloy steels that warp little. Even experienced blacksmiths end up with a few rejects due to cracking and excess warpage, which perhaps explains the relatively high cost of handmade ones. It has mostly been a tool made by specialist blacksmiths.

For this reason, and because the performance demands on the cutting edge are not severe, Blue Label steel is entirely acceptable IMO.

The Ura

I mentioned the “ura” above, but let’s examine it a bit more. Ura is a Japanese word written using the Chinese character  浦. It means a bay or inlet from a lake or ocean, usually without lots of rocks, and often with a sandy or gravelly shore. You can imagine why this word was employed to describe the hollow-ground depression in many Japanese woodworking blades.

In North America, similar curved surfaces and depressions were once called “swamps” even though they were made in metal. This term is obsolete nowadays.

The ura is what makes the Japanese marking knife superior to its Western counterparts for two reasons. The first reason is that the ura makes it easier to keep the hard layer of steel at the reference side flat. Second, in light of the hardness of the cutting edge layer, the ura makes it easier to sharpen the cutting edge.

Without the ura, the hard steel would be time consuming to sharpen and would tend to become rounded instead of remaining a flat reference face to index against a steel square or straightedge. It’s a subtle and clever design more sophisticated than its simple appearance suggests.

In use, the flat ura side is pressed lightly against the leg of a steel square with the point cutting lightly into the wood and the heel floating above. The blade is then pulled toward the user to cut the straight layout line.

Lubrication

I recommend Beloved Customer use an oilpot to lubricate the marking knife’s blade to reduce friction and wear between the blade and the square, as well as friction between the cutting point and the wood. Not only will  your square last longer, but your layout lines will be more accurate. Don’t believe me? Give it a try.

Recommended Modifications

Marking knives are simple tools for a simple job, but there are a couple of subtle improvements some advanced Japanese craftsmen, especially joiners, make that Beloved Customer may want to consider.

1. Habiki

The first improvement is intended to minimize one downside of the marking knife, namely its habit of shaving metal from the square or straightedge used to guide it. In Japanese this modification is called ” habiki “ 刃引き which translates directly to “ blade pulling, ” as in pulling the blade’s cutting edge over a stone to intentionally dull it. It is a term borrowed from the sword world.

The steps to accomplish this modification are as follows:

  1. First, sharpen the blade;
  2. Then, with the tool’s ura side facing you, stand the blade vertically on its cutting edge on the face of a medium grit waterstone or oilstone with the last 2~3 millimeters of the blade, measured from the tip, hanging off the stone’s side so the tip does not contact the stone;
  3. Finally, drag the blade towards you creating a flat on the cutting edge, while leaving 2~3mm of the blade’s tip sharp. Voila.

The dulled portion of the cutting edge will now be less likely to shave your square or straightedge, while the sharp tip will cut the wood and make a pretty, accurate layout line, assuming you do your job, of course.

I know that the idea of sharpening a good blade and then intentionally dulling part of the cutting edge sounds gaga. In fact, when Honda-san showed it to me, I thought the old guy was pulling my leg. But Honda-san was a master among masters, a man in his 80’s who had been making extremely high-end custom joinery since he was 15 years old, one who took his tools extremely seriously. In addition, he let me try his knife so I was quickly convinced.

Honda-san’s technique works, so gather up your courage and give it a try before allowing your inner-troll to embarrass you. I promise you’ll like the results and your square will thank you.

2. Tip Bevel

The second modification is also one Honda-san taught me. There are several ways of doing it, but the essence is to grind an angled flat 15~18mm long  on the top edge of the blade’s side angled away from the ura, ending at the cutting edge’s point. The goal is to create a very sharp “clipped” point.

This angled flat has three purposes: First, it removes metal that would otherwise get in the way of your clearly seeing the knife’s cutting tip. This is important because often a knife must be indexed off a tiny divider point’s mark or a previous layout line, for instance when marking the shoulders of a tenon on four sides of a stick of wood. Removing this unnecessary metal will make it easier to begin the mark exactly where it is needed.

The second purpose is to reduce the friction between blade and wood when cutting a layout line, thereby improving control like racing tires on a fast car.

And third, it provides a convenient place to rest your fingertip to better control the knife.

If you imagine this modification can’t make much of a difference, then your lack of experience is showing. How embarrassing >~(ツ)~<

The Square

I know there are those who prefer to use a wooden square for layout work, and others who like brass ones. Both work just fine with a marking knife until they don’t. You would be wise to consider using a hardened steel square, or better yet, a precision hardened stainless steel square with your Japanese marking knife; They simply last longer and stay straighter.

There are hardened carbon steel and hardened stainless steel combination squares and die maker squares available on the market, but I think they are too bulky and too costly for making simple 90° layout lines on wood.

Matsui Precision produces a series of excellent hardened stainless steel squares that are popular in Japan and well worth the cost. I have been using them for years. Send me a note if you are interested.

The Japanese marking knife is a great tool. Once you use one, especially after making the modifications described herein, you will wonder how you ever got decent layout work done before.

YMHOS

My old marking knife was hard on my eyes and fingers, but now I know how to fix it!

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.

Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google, fascist facebook, or thuggish Twitter and so won’t sell, share, or profitably “misplace” your information. May my square always lie to me if I lie to you.


The Japanese Sumitsubo Inkpot 墨壺: Part 1

If your wife’s having a good time and you’re not, you’re still having a better time than if you’re having a good time and she’s not.

Red Green

The sumitsubo is a Japanese marking and layout tool similar in function to the Western chalk line. Although few Gentle Readers in Western countries have experience using this tool, it has much to recommend it.

In this post we will briefly examine this tool so prevalent in Asia. Our focus however, will be on the traditional wooden versions, not the modern plastic one, a version of less beauty but perhaps more utility

Sumitsubo is written using the Chinese characters 墨壷 which directly translates to “ink pot”  and pronounced “sue/me/tsu/bow.”

The inkpot has been a common tool in many Asian countries since ancient times. Indeed, until recently, few craftsmen in Asia had even heard of the dusty chalkbox used in the West.

This is just conjecture by your humble servant, but the fact that nearly all writing and much artwork in many Asian countries during recorded history relied heavily on brushes and sumi ink, the black carbon reside of burnt pine sap, may be the reason the inkpot became the standard tool for marking straight (and sometimes intentionally curved) lines.

Using the Sumitsubo

The sumitsubo works on various surfaces including wood, stone, concrete, gypsum board, and other construction materials. It is not unique to Japan, but is found in one form or another throughout Asia. It is an essential tool for carpenters.

A thin line spooled around a reel attached to the sumitsubo passes through holes at each end of a “pond” or inkwell filled with absorbent silk or cotton waste soaked with ink. As the line is let out, and with encouraging pressure applied by the user, it soaks up ink from the inkwell.

In Japan, a wooden bob called a “karuko” with a sharpened steel pin is attached at the line’s far end. The workman pushes this pin into the surface of the wood being marked to secure the end of the line in place for marking. 

To use the sumitsubo, the workman stretches the damp inkline over the surface of the object to be marked, secures it in the desired position at the far end using a pin, weight, or helper, reels out and stretches the line, picks up the line with his fingers and releases it snapping an inkline. There are other more subtle actions that the user must perform at the same time, but this is the essence.

Depending on the user’s skill and the available line, a perfectly straight line can be marked on a flat, level surface to many meters in length.

The ink line has several undeniable advantages over the Western chalk line. First, the line it leaves is narrower and less “ fuzzy,” sufficient for fairly accurate carpentry work, much more precise than the typical chalk line.

Second, it is not as easily rubbed off or blown away as chalk.

Third, while inks of various colors can be used, black is most common and contrasts nicely with most building materials, but red is another traditional color. Nowadays, ink can be purchased in a rainbow of colors, some in permanent ink and even some that glow-in-the-dark.

The standard variety of ink used with sumitsubo is not entirely waterproof and if applied to a non-absorbent material like stone or steel, will not endure a rainstorm well. There are waterproof inks available, however, and of course the standard trick of using a spray can of clear lacquer to seal the snapline works as well with ink lines as it does with chalk lines.

History and Design

As your humble servant has mentioned in previous articles, the marketplace development that makes it possible to purchase completed woodworking tools is fairly recent. In previous centuries and millennia, when material costs were high and labor costs low, craftsmen would commission a blacksmith to make the metal components of their tools, but would make the wooden components themselves. In Japan at least, the sumitsubo too was made by the individual craftsman and became an opportunity to display both his skills and imagination, yielding unique, beautiful, and even bizarre tools.

There is neither adequate time nor space in this insignificant little blog to go into the evolution of sumitsubo design in any detail, much less the design variations, but the Takenaka Tool Museum’s website has pictures of representative examples.

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An old “Ichimonji” style sumitsubo. These squarish sumitsubo have their own charm, but are not as functional or convenient as later designs.
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This antique sumitsubo shows the design evolution of the tool with the narrow tail, which is easily held, the large reel which not only holds more line but helps the line dry retarding fungal growth, the wide and shallow pond, and the ceramic ferrule for the line. The owner used this tool exclusively for red ink. This sample does not have a crank for working the reel, typical of Western Japan.
A fancier craftsman-made version of the sumitsubo above, with a smaller pond, a hand crank, and a more elegant wave motif

The style used for the last 200 hundred years or so is shown at the top of this post, and in the photo below. The major improvements include a larger ink pond designed to both hold more ink and to better accommodate the bamboo sumisashi inkpen used for layout, a larger, more exposed reel to hold more line, making it quicker to reel in, and providing better ventilation to reduce mildew, and a narrower, easier to grip tail containing the reel greatly improving functionality and reducing fumbling and damage.

A typical sumitsubo nowadays with crane and turtle facing each other across the ink pond, no doubt talking about sports scores. Zelkova wood

The carving seen in sumitsubo has meanings, of course, which varied with the craftsman and popular whim. The most popular style nowadays has a turtle and a crane facing each other across the ink pond. In Japanese mythology, both are considered lucky, with the crane said to live 1,000 years and the turtle 10,000 years. The turtle normally has a hair skirt flowing behind.

A very artistic craftsman-made sumitsubo with a peony blossom and Chinese lion holding court at each end of the ink pond, and a lotus leaf reel. These three symbols hark back to a famous Japanese Noh play titled “Shakkyou.” The lion in mythology is the king of beasts. It drives away demons and evil forces and protects against disease. The peony is the king of flowers. The lotus is a thing of grace and beauty that lives in, yet floats above the dirty mortal world, and with its roots purifies it. A potent symbol in Buddhism as well. However carved this sumitsubo was well-educated, but the size of the lion on his precarious perch would limit the practicality of this tool.
Bottom view. Notice the opening below the reel to intended to promote air circulation
A side view of the Chinese lion, facing away from Gentle Reader. No offense intended, of course, but dignity must be maintained.
A professionally-carved sumitsubo by Kimura Isaburo showing lotsu leaves surrounding the ink pond with a tiny frog poised on the rim
A closeup of the lotus ink-pond’s froggy.
Another sumitsubo carved by by Kimura Isaburo. This one too has a tiny frog on the rim of the ink pond, but instead of reposing, he is preparing to jump to escape the snake on the opposite edge. The body of the snake wraps around the wheel and tail of the tool.

Dragons are another mythological motif seen in sumitsubo, being a fierce but noble and benevolent creature in Japanese tradition

The reel end of the sumitsubo typically incorporates water or wave details, perhaps related to the ancient Japanese motif of wagon wheels in flowing water.

The last sumitsubo maker in Niigata Prefecture was Mr. Tamaki (RIP). Those Gentle Readers who have visited Kezuroukai competitions in Japan may have seen him doing exhibitions. Here is a link to a video of him making sawdust.

Here are a few links to videos of sumitsubo in use: Link 1 Link 2 Link 3

Here is a link to a video of a huge (2.3 shaku = 700mm = 27.4″) sumitsubo by a famous Niigata craftsman named Ichimonji Masakane. The size brings the carving details into focus. This is of course not a practical tool, but was created for decorative purposes. Once, every major tool store had a similar sumitsubo on display. If you visit Suiheiya in Tokyo you can see similar examples.

The sumitsubo is a tool Western woodworkers could benefit from when making straight layout lines because it’s not only cheaper, more convenient and more reliable than a long steel or wooden straightedge, it produces a finer, easier to see, and more indelible mark than a chalkbox can.

The sumitsubo was once said to be the symbol of the master carpenter, the craftsman that created the design and performed layout of major aspects of a construction project. Even today, older carpenters prefer the wooden sumitsubo and inist that it does a better job. I suppose every generation in human history had similar attachments to older ways and older tools. But I have a hand-carved Zelkova wood sumitsubo mounted under the lid of my toolbox. Does that make me an old fart?

A drachma for your thoughts.

YMHOS

A sumitsubo at work.

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