“Why do shakuhachi crack?”
Shakuhachi crack because of an imbalance of moisture loss or gain which is usually caused by changes in the level of humidity. Lacquering every single surface of a shakuhachi is perhaps the best way to prevent cracking because it will stop the bamboo from experiencing shifts in humidity (see photo above). However, many shakuhachi are only lacquered on the inside (pictured left). While this helps prevent cracks from any sudden introduction of moisture to the inside of the flute, it increases the chances that a shakuhachi will crack at rest. This is because lacquering only the inside of the bamboo creates an imbalance by making the inside impermeable while leaving the outside permeable. This causes an uneven loss or gain of moisture which in turn leads to cracking. Un-lacquered shakuhachi are more susceptible to cracking from the sudden introduction of any moisture, usually from the breath or from cleaning. In the end, fully-lacquered is the best option for longevity while it’s a toss-up between just lacquering the bore and no lacquered at all. You can read more about urushi lacquer here.
“How can I prevent my shakuhachi from cracking?”
The best options, though understandably not for everyone, is to have a shakuhachi fully-lacquered, fully-bound, or both. If these are not options or desirable then proper storage and care must be adhered to diligently. Since bamboo can crack when there is a large enough drop in the humidity it is advisable to store your shakuhachi in an air-tight bag or case. Generally speaking, around 50% humidity is desirable for preventing cracks. Avoid leaving your shakuhachi out of its protective bag or case especially when you find yourself in harsh dry environments such as; AC, around heaters, camp fires, in closed automobiles, deserts, beaches, snow, and so on. Too much humidity can be as detrimental as too little so it is best to regulate humidity. One elegant solution to this are silicone humidity regulating beads. If a shakuhachi should crack it can almost always be repaired.
“Should I oil my shakuhachi and does it help”?
I do not recommend oiling shakuhachi. It can possibly help prevent cracks in shakuhachi but very few oils will actually work and they have to be applied expertly. Furthermore, these oils have strong odors which I personally do not find pleasant. If you oil a shakuhachi it will most likely make it impossible for lacquer to adhere to it which should be kept in mind if lacquering might ever be desirable. There is no reason to oil a lacquered flute and it would be quite disgusting! I also turn down any returns or trades if a shakuhachi of mine has been oiled.
“Can pre-binding prevent cracks?”
From my experience pre-bindings will prevent cracks in most cases. Pre-bindings are bindings that are applied before cracks appear. Bindings are wrapped under extreme tension and are secured with a special slipknot and then further secured by sealing with glue or lacquer. Sometimes small cracks may form after a flute has been pre-bound but they will often not go far or require further repair.
“Do cracked and repaired shakuhachi sound different?”
Cracked and repaired shakuhachi usually sound the same because the bamboo will join back together like two puzzle pieces. That is unless integral adjustments to the bore are effected such as additions to the bore using paste (jinashi or jiari). Pictured below is a 1.8 “D” shakuhachi I made for a student of mine which suffered a crack. He lives in Arizona and he was very concerned that the crack would be an issue, however, I assured him that it would be just fine. Fortunately none of the additions to the bore were harmed, though if they were I could have fixed them as well. To date, the instrument has not suffered any more cracks and the existing crack has not moved.
Click images to enlarge
Below are images of a jiari type shakuhachi made by a Japanese maker which cracked. Thankfully none of the plaster on the inside came loose! As you can imagine, cracks in jiari can be much more troublesome due to the plaster (ji), lacquer (urushi), and blowing-edge inlay or utaguchi. This customer chose a nice deep burgundy binding cord which resembles the cherry bark used in many fine Japanese crafts. I added brown kijomi urushi and buffed it out on the center joint rattan veneer for a nice effect that would blend well with the new bindings.