Lacquer on shakuhachi
Above is proper urushi repair job I applied on the center joint of a jiari shakuhachi. Two types of specific urushi must be used in many layers and have to be properly cured to prevent allergic reactions (more on urushi/poison ivy allergies below).
Lacquer has many effects on shakuhachi. Lacquering the bore effectively makes it acoustically smaller by speeding up air-flow. It makes shakuhachi play louder and with a more sharp or crisp tone color. Whether this is better than the sound of an unlacquered bore depends entirely on the sound desired by each individual. An advantage to a lacquered bore is that it hardly ever grows mold and if it does it is easy to clean. Natural bamboo bores can grow mold much more easily and usually require periodic cleaning with distilled white vinegar and a dryer vent brush.
Shakuhachi crack because of an imbalance of moisture loss or gain which is usually caused by a changes in the level of humidity. While lacquering the inside helps prevent mold and cracks from the sudden introduction of warm breath, it actually increases the chances that a shakuhachi will crack at rest. This is because lacquer creates an imbalance by making the inside impermeable while leaving the outside permeable. In the end it’s a toss-up and becomes a matter of personal preference. You can read more about cracks here.
About Japanese urushi lacquer
Urushi lacquer is made from the sap of the urushi tree. The sap contains “urushiol” which is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron (e.g., poison oak, poison ivy, poison sumac). Cashew, mango, and pistachio are also in the same family and a lower quality lacquer is made from cashews. In sensitive individuals, urushiol can cause an allergic skin rash on contact known as “urushiol-induced contact dermatitis” AKA “poison-ivy rash”. The name comes from the Japanese word for the sap of Toxicodendron vernicifluum (漆 urushi). The oxidation and polymerization of urushiol in the tree’s sap when in the presence of moisture allows it to form a hard lacquer which is used to produce lacquerware.
The sap of the Japanese urushi trees contains the highest concentrations of urushiol thus forming the strongest and most adhesive urushi. Urushi made from Japanese urushi tree sap was so much more adhesive that the “maki-e” or “metal leafing” technique could only develop in Japan. The shakuhachi and its ancestors have been lacquered both inside and out with urushi lacquer for centuries. The komuso monks often applied urushi lacquer to the entirety of their shakuhachi which served to protect their shakuhachi from the elements and is perhaps the best way to prevent cracks.
Japanese urushi lacquer history
During the Edo period (1603-1867) the urushi tree was highly valued being proclaimed as one of the “shimoku” (four essential trees). There was an urushi-tax and people had to pay a part of the tax with urushi and urushi-wax which was made from urushi seeds and was used for the production of candles. There was also an urushi magistrate who collected the urushi-tax and took care of urushiware which belonged to temples and shrines.
There were special urushi craftsmen who traveled around the whole country to repair and maintain urushiware. Until 1959 the production of urushi-liquid was at its height and urushiware was still used daily. Urushi-liquid collectors earned a fortune with their work. However, from 1960 and onward cheaper urushi was imported from China and the employment of the urushi experts decreased.