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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.
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.
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.
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
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