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 decide 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.

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