History and Description
The shinai was invented in the mid-18th century, along with specialized armor (bogu), to permit students of kendo to spar safely and realistically even at the beginners' level, moving beyond the practice of kata.
A typical modern shinai is made from four staves of bamboo held together with several pieces of white leather and a durable himo (string). Properly arranged, these staves slide against each other in such a way as to yield upon impact, minimizing damage both to the weapon and to the target. Not all shinai are created equally; several types exist based on varying shapes of staves, all differing in balance, ease of handling, and effectiveness. A run-of-the-mill practice shinai will set you back between $20-$30, and a high-quality model between $50-$100.
More recently, shinai with staves of carbon graphite and resilient plastic have been invented. Where a bamboo shinai requires maintenance (see below) and will break after several months of use (depending on how roughly it is treated), these carbon graphite models will last for years. They cost $200-$400, but considering the consistent need to replace the bamboo swords, many kenshi (practitioners of kendo) find the investment worthwhile. These shinai are said to have much the same feel and performance as the normal ones, and they have been approved for use by the various world kendo federations, but they do have some drawbacks. Perhaps most importantly, the sound they make upon impact is different from the sound bamboo makes; the fact that the shimpan (judges) rely on their ears as much as their eyes when calling points makes this a significant consideration.
Care and Feeding of Your Shinai
Proper maintenance of bamboo shinai is essential to ensure that your weapon will have a long life of good performance. Also, and much more importantly, it will dramatically reduce the risk of injury to yourself and your sparring partners. Shinai can splinter, crack, and break. If left unchecked, these problems can result in severe injuries even to an armored kenshi; flying splinters and individual staves can slip right through the slots in a men (piece of head armor).
You will need some fine-grained sandpaper, a rag, some oil (gun oil and vegetable oil work well), and possibly a pair of scissors.
Remove the tsuba (hand guard) and the piece of rubber holding it on, if these are attached. If the shinai is brand new, it will also be tied together with packing string (thinner than the himo, and horizontal as opposed to vertical). Cut these off and throw them away. Now, look for the end of the string at the handle (you may have to poke around for it; it will probably be tucked behind a strip of leather). Untie it. It, the nakayui (strip of leather near the center) and the sakigawa (leather tip) should now slip off easily. Do not untie the string from either of these pieces of leather; putting them back on is a pain in the ass. Be careful not to lose the squarish piece of plastic in the tip of the shinai that holds the staves apart.
Examining and Fixing the Staves
Now, pull off the handle, set it aside, and gently pull apart the four staves. They should come apart fairly easily, although the metal square near the bottom (which you should not lose either) may cause them to stick a bit.
Look carefully at the staves, especially the edges that rub against each other when the shinai's used. Are they sharp and angular? If so, sand them down lightly until they're smooth and just a bit rounded. Are there any splinters? Sand those away too. Examine the rest of the staves for cracks. If you find a significant crack, that stave will probably need to be thrown away. Don't fret, though, because you can substitute a stave from a newer shinai. I recommend buying three or so shinai at a time, making sure that the "knuckles" on the bamboo match somewhat on all of them, so that you can have a reservoir of spare parts to save money.
This next step is especially important if you live in a dry climate. Being a plant product, a bamboo shinai will eventually dry out, and dry bamboo is brittle and more likely to break. Grease up your rag with a little oil and coat each stave of the shinai. Ideally, you should allow them to soak for several days, wiping off the excess oil with a paper towel at the end of that time.
Reassembling a shinai is not rocket science, but it pays to practice a few times so that you won't be slow at it when it matters. Basically, reverse what you did when you took it apart. Fit the staves together, put the handle loosely onto the end, slip the nakayui and sakigawa over the other end (don't forget the square plastic doohickey!), and jimmy the handle on more tightly. This can be tough, especially the first few times, but you'll manage. It will go all the way on; there should be no unfilled space at the end of the handle. Re-tying the knots is hard to describe in words, but it is not complicated either. Just compare your completed shinai to that of your buddy, and ask your sensei or a higher-level student if you're unsure. The string should be fairly tight and give a nice "twang" when plucked.
Before Every Single Practice
Check the shinai's edges for cracks and splinters (this can be done by squeezing it to expose the inner edges; it is not necessary to disassemble it). Pluck the string; is it nice and tight? If not, untie it, stretch it tight, and re-tie. The leather on a shinai will stretch and loosen with regular use, which will cause the string to loosen and go slack. These are the only steps which need to be performed each time; oiling should be done every few weeks, less if you're lazy like me.
Sources researched for this writeup:
- The Shinai Maintenance Page: http://members.tripod.com/kumdo/jukdom.html
- E-Bogu: http://www.e-bogu.com/
- "Shinai" at Wikipedia: http://en.wikipedia.org/wiki/Shinai
- "History of Kendo:" http://www.ee.surrey.ac.uk/Societies/kendo/KendoHistory.htm
- The wonderful Kendo node by Bobby_Reb et al