Sacrilege! How can one consider a synthetic substance as a substitute for wood? And yet . . .I would wager that were one to go back in time and present Matsumoto Bizen no Kami or Tsukara Bokuden with an unbreakable staff or bokken of, say, extruded nylon, they’d demand more of the same. (Notice the advent of carbon-fiber shinai for an example of this in modern budo). Therefore, despite my passion for wood, I’m also researching substitutes.

When considering archaic martial arts, we often do not consider the socio-economic matrix from which they emerged. Were a teacher to need wooden swords in the Muromachi or Edo periods, he could easily go to a craftsman, and order a bundle of ten or twenty for a few pennies. A bokken today can easily cost over $100 and a nine or ten foot spear can run $300 or $400. Because of this expense, practice can easily become impaired or distorted. In schools where heavy impact of weaponry is the norm, one may well be hesitant to strike the opponent’s spear and break it at $300 a weapon. You can end up with anemic practice, where one makes assumptions what would happen if you hit with full impact at the proper angle.

For this reason, I am researching synthetic materials not to replace, but to augment training. They can really be used to pressure test techniques.  Just as wood practice weapons augment steel, so synthetics can augment both steel and wood.

I will note if I’ve personally tried a particular option.

Extruded Nylon

I have used extruded nylon rods for the cross-piece for kagi-naginata. Diameter is about ½ inch, and they are nearly unbreakable. I also used 1 ½ inch diameter, seven feet long extruded nylon rod for ‘spear shaking” training, instead of the traditional Chinese wax wood. I investigated a tapered extruded nylon length for spear and was informed that this is impossible – it would have to be milled (for example, on a lathe, or perhaps with a plane).

 Delrin (Polyoxymethylene/POM or acetyl rod)

An informant writes: “It has less flex and higher density than polypropylene and from an engineering standpoint, it’s attributes are more consistent than wood. I have a tanbo made out of the material and it has taken a lot of impacts that wood could not have survived.” It can be acquired at: E-Plastics or Professional Plastics

Enhanced Appalachian Hickory Bokken (Review by Jimmy Sorrentino)

For the past several months, I’ve been practicing with an Enhanced Appalachian Hickory Bokken I received for evaluation from Kingfisher Woodworks of Wilder, Vermont. I’ve used it for both paired practice and suburi, in aikido classes and seminars, as well as at home. I am pleased to report that Kingfisher has produced an excellent weapon, as durable as it is elegant.

Brad Goedkoop, Kingfisher’s proprietor, has been making wooden weapons for almost 25 years. Mr. Goedkoop, whose martial arts background includes aikido and traditional Japanese sword arts, acquired his woodworking expertise through the practice of fine carpentry. He came to realize that making traditional Japanese training weapons is different from other woodwork. As Mr. Goedkoop states on the Kingfisher website, “Unlike most creations in wood, the success of [these products] depends on their actual feeling when held.”

Kingfisher crafts bokken, shoto, and tanto inspired by the line and balance of live blades, while retaining the sturdiness required for intense daily practice. (I acquired a complete set of Kingfisher weapons in July 1991 which I still use regularly.) As Mr. Goedkoop’s website states, “The history of the Japanese sword spans about a thousand years. Over that time, the essential features of Japanese blades are remarkably uniform but we see differences, mainly nuances, in their shape. Some are longer by a few inches, some shorter, some with more pronounced curvatures, some heavy and others light in weight. Many bokken reflect these differences but we also see wooden swords that are not direct imitations of live blades. In fact, Japanese wooden swords are not generally intended to mimic the shape, weight or feel of a live samurai sword but instead intended to develop specific skills and facilitate specific movements.” Kingfisher also makes a jo–a weapon in its own right–that handles in a lively and responsive way.
Over the years, Mr. Goedkoop has used various exotic and domestic hardwoods, as well as manufactured materials such as laminated rosewood composite (also known as LRC, a forerunner of DymondWood®), in the manufacture of Kingfisher weapons. He eventually settled on air-dried Appalachian hickory, which he offers in different grades, depending on density, specific gravity, and appearance. According to Kingfisher, Appalachian hickory compares favorably with Japanese white oak (shiro kashi) for shock strength (it is hard but not brittle) and dent resistance–and it is available from well-managed domestic sources.
In his efforts to improve Kingfisher weapons further, Mr. Goedkoop drew on his experience manufacturing skylights for the construction industry in the Denver, Colorado area from 1978 to 1986. His company was one of the largest local users of acrylic sheeting, and he came to appreciate the material’s dependability, durability, and strength. Acrylic’s successful 70-year track record, its lack of toxicity and its resistance to weathering were additional advantages.
To produce an ‘enhanced’ weapon, the wood is infused with liquid acrylic (methyl methacrylate) using a vacuum-pressure cycle. The wood is placed in a heavy steel containment vessel, and a vacuum is pulled on to remove the air entrapped within the wood’s pore structure. Liquid acrylic enters the container, which is then pressurized. This forces the liquid acrylic into the pore structure of the wood. The liquid acrylic solution contains both a cross-linking agent and a catalyst. The treated wood is heated to a temperature where the catalyst becomes active and polymerization occurs. The polymer is located in the cell lumen and cell wall. In other words, it’s completely through the wood. The final wood/acrylic composite is much harder than the untreated wood.
Of course, like any other wooden weapon, the enhanced bokken is not indestructible. Any wood is subject to denting, splintering and breaking. Kingfisher provides a guide to breaking in and maintaining its weapons on the website. One interesting effect of the acrylic on the hickory is that small dents appear to ‘heal’ partially over a period of weeks as if the cells of the wood were attempting to return to their original shape.
The bokken I received for evaluation is 42 inches long, and weighs 29 ounces. The tsuka is 11.75 inches long, with a clear transition to the blade. The tsuka is elliptically cross-sectioned; the major axis is 1.6 inches, and the minor axis is 1.1 inches. The balance point is 18.75 inches from the kashira. The maximum depth of curvature is .375 inches. The mune is well-defined. The kissaki is the complex chisel-style of the aikiken and Katori bokken. The wood has a tight, straight, smooth grain with a warm golden color.
The bokken handles quite well. Because the acrylic has added to its density, it is heavier than one would expect, yet it does not feel club-like. The gentle curvature and the refined line produce a blade-like feel in the hands. Although it is not tip-heavy, Fred Little made the interesting observation that the bokken ‘feels longer than it is,’ which I attribute to its superior balance. The finish of the bokken is superior. It is smooth but not slippery, eminently ‘grippable,’ but not sticky. The kashira has a slight bevel which is pleasing in the left hand, while the transition at the front of the tsuka provides immediate tactile and visual signals of proper right hand placement to those who do not use a tsuba.
The Kingfisher enhanced hickory bokken is ideal for the serious aikido practitioner. Seriousness is not a function of the length of time of one’s practice, but the intensity and quality of that time as one devotes a significant portion of one’s life to the pursuit of proficiency in the art. High-quality tools are no substitute for proficiency; however, the use of such tools makes the pursuit of proficiency easier and far more enjoyable! The Kingfisher enhanced hickory bokken may not be your first bokken, but it could be your last. I strongly recommend it.