by Koji Murakami (adapted from The Wooden Post, vol 9, December 2017)
The following article appeared in the Kezurou-kai Japan newsletter No. 71 from September, 2014. (translated by Noriko McAneny)
The yariganna is a rather difficult tool for the beginners to use, and the sharpening requires some different practices compared to sharpening other woodworking blades. There are two types of yariganna: one with a curved sharpening face that was resurrected in the Showa Era (~1926 to 1989), and the other with a straight edge developed by Kezurou-kai Japan. I’ll show you my way of sharpening both of these blades.
Picture 1:
The biggest difference between Yariganna and other woodworking tool blades is that for yariganna the back of the blade edge wears off by usage. The “ura dashi” work is harder compared to dai kanna, so I sharpen the back of the blade until “ha gaeri” (burr) is seen. This creates “beta ura”, a wider flat surface, between the edge of the back of the blade and the concave part. I think it’s fine to be this way since it won’t tear out as much wood compared to “ito ura” (narrow).
Sharpening for yariganna with straight blade edge:
Picture 2: (medium-rough stone)
You can use a regular (flat) sharpening stone. However, you need to be careful about the stone surface condition. The diagonal sharpening and the blade width difference create uneven wear. I frequently correct the sharpening surface.
Picture 3:
The sharpening stone surface needs to be corrected before proceeding to the opposite side. A left hand is used to sharpen it while holding a blade tip. It’s dangerous, but I think this probably is the only way. You would not cut your finger tip unless some blade parts got caught on something or you got off balance and mishandled it.
Picture 4: (finishing stone)
Finishing will be done a similar way. Unlike nomi and kanna, it’s difficult to finish with short repeating strokes. So that it’s very important to sharpen the entire blade edge thoroughly before the finishing stage. Otherwise the edge will not stick to the finishing stone well. For this reason, I emphasize you should frequently correct the medium-rough stone surface. Here I’m holding the blade by my left hand only for the picture, but both hands are used for sharpening.
Sharpening for yariganna with curved blade edge:
Picture 5: (medium-rough stone)
This blade, a restored ancient type, was made by Shirataka-san. This is a Tosa hamono style yariganna, not filed and finished front and back, only formed by hammering. The sharpening stone was modified to a semi-cylindrical shape to fit the curve of the blade. You need to make another semi-cylindrical medium-rough stone for a different curved yariganna.
Picture 6:
The blade excluding the pointed end part is sharpened perpendicularly to the edge. The diagonal sharpening makes the blade surface bad, so it’s no good. The sharpening will cause the surface wear, so you need to pay attention to the condition of the curved stone surface and correct it if necessary. If you keep using the worn (bellied) stone so that the sharpened edge face becomes wider, it’s impossible to do the finishing stone work later.
Picture 7 and 8 (above):
Sharpen the top 1/3 of the blade to the tip while sliding along the stone back and forth imagining the sharpening blade edge being kept perpendicular (ie, to the stroke at each point along the curved edge). As if bringing the angle of the sharpened face closer to the handle to the blade tip.
Picture 9 and 10:
Next is the opposite side. I don’t change the blade holding hand for this type of blade. Unlike the straight yariganna, it’s difficult for me to sharpen by the non-dominant hand. Please use the non-dominant hand if you can do so.
Picture 11: (finishing stone)
You can prepare an individual finishing stone for each curved yariganna, but I use one finishing stone, making it a bit more rounded, for more than one curved yariganna. It would be quicker and cleaner when you use a finishing stone prepared for the individual curved yariganna. But I do it this way since I can’t avoid sharpening the edge with short repeated strokes. A smaller stone is more suitable for the curved blades.
Picture 12:
I am frequently asked how to take care of the warped back side of the blade. Of course there is no such metal for yariganna “ura oshi”. The back side is sharpened by a medium-rough stone using a short back and forth motion, and “ha gaeri” is removed rubbing on a finishing stone.
I talked about yariganna sharpening here, but no quality finishing stones from Kyoto had been discovered in the Nara period when the yariganna was used. Temples and the Imperial Palace of Nara were vermillion-lacquered, so a slick, smooth wood surface would not be suitable for painting. I wonder how sharp yariganna might have been then. I also wonder how they were sharpened: the blade removed from the handle and sharpened, sharpened like a sickle, or sharpened like a Western knife – holding a sharpening stone and rubbing against it? Unfortunately there are no materials such as pictures and document available for us to know the facts. So I dream about the ancient yariganna.
Next time, I’ll talk about how to use the yariganna.
Koji Murakami is a miya-daiku (temple carpenter) whose work includes restoration at Yakushiji Temple under Master Temple Carpenter Naoi-toryo during the time Nishioka-toryo was leading the work. This article is but one installment of his series begun in 2014.
