Koboku - fragrant wood - to the Japanese is more than just the foundation on which the majority of Japanese incense is built. It's rare and fragrant properties posses historic, cultural, and spiritual association that transcend the simple commodity of incense, transporting the listener beyond the sense of smell. As such, there is no better place to start to discuss Japanese incense than by exploring the traditional Koboku used in Japanese incense.
Known for its ability to calm the mind, Byakudan (Sandalwood) is one of the oldest known fragrant woods. Considered sacred in many religions, including some schools of Buddhism that brought incense to Japan, Byakudan is often the primary ingredient of many Japanese incense recipes.
Byakudan is harvested from the heartwood and roots of Santalum album (Indian Sandalwood) native to India and southeast Asia. Taking up to 15-20 years to reach harvest, or 60-80 years to reach full maturity, wild Santalum album are considered a vulnerable threatened species due to over harvesting and outright poaching. In commercial plantations, the tree is usually uprooted during the rainy season when the soil is soft and concentrations of sandalwood oil are highest, especially in the roots. Sapwood is lighter in color and not considered fragrant. Byakudan heartwood and roots have a reddish color and are valued for their warm, creamy, slightly sweet, fragrance.
Prized for its relaxing properties, Byakudan is thought to increase focus during mediation by creating a deeper relaxed state. It is said to lessen anxiety, promote healing and purification, and aid as an antiseptic and insect repellent.
Known by many different names - Aloeswood, Agarwood, Eaglewood, Oud - Jinko has a wonderfully rich fragrance that can vary from sweet to spicy to sour to hot to bitter - or a mixture of these. Because of this exceptional fragrance, it also has a deep spiritual significance, being mentioned in some of the oldest spiritual texts such as the Torah, the Bhagavad Gita, the Sushruta Samhita, Islamic scriptures and the Christian Gospels.
Jinko is formed within several species of the evergreen Aquilaria tree native to northern India, Laos, Cambodia, Malaysia, Indonesia, and Vietnam. It is important to note that not all Aquilaria trees will produce Jinko. Instead Jinko is formed by the tree as an immune response to fungal infection. Prior to infection, the heartwood of the tree has no medicinal or fragrant properties. Once the fungal infection takes hold, the heartwood and roots of the tree fill with a protective dark resin in response. After years of fighting the infection, the amount of resin produced increases the density of the wood to the point that often it will sink in water rather than float. Hence the Japanese refer to this dense dark resonated wood as "Jinko" - sinking wood.
Naturally infected resonated wood is very rare, with estimates of as few as seven-percent of wild Aquilaria trees eventually producing resin. Due to increasing demand, dwindling natural supply, and its increasingly rare nature, all Aquilaria species are listed as a potentially threatened with trade heavily monitored and restricted. In response, Aloeswood plantations where Aquilaria trees are intentionally wounded to promote fugal infection and associated resin filled wood have grown as an industry. However, commercially created Aloeswood is still considered inferior to "wild" aloeswood.
Considered a sacred wood by many religions, Aloeswood is said to increase awareness, posses psychoactive properties, and aid in the movement and balancing of chi.
Traditionally considered the highest grade of Aloeswood, Kyara is the most rare of koboku, and the most prized. Worth more per ounce than gold, Kyara is one of the most fragrant and rare substances on earth.
No one is quite certain how Kyara is formed, and there is speculation that it may not even be a form of Aloewood, but instead completely distinct in its own right. Evidence for this includes several reasons. Historical artifacts from Vietnam display carvings distinguishing between two tree types - one for Aloeswood and one for Kyara. Often softer and less dense than Aloeswood, the highest grade Kyara rarely sinks in water as many Aloeswoods do. Fragrance is released at a lower temperature - 150ºC for Kyara compared to +200ºC for Aloeswood. Finally, Kyara is also sourced from a smaller area than Aloeswood - Vietnam, Cambodia and Southern China exclusively.
Regardless of whether Kyara is or isn't Aloeswood, it is exceedingly rare and wonderfully fragrant. There are no cultivated sources of Kyara currently, as there has been no success in cultivation of such a rare and mysteriously fragrant material Kyara represents. Due to this, world supplies of Kyara continue to diminish and costs continue to grow. Prices for whole pieces of "wild" Kyara in their natural form can sell for more than $2,500 per gram! Baieido's sublime Kyara Kokoh - regarded as one of the world's finest incenses - retails in the US for approximately $83 a gram. For comparison, as of this writing, gold is selling for $51 per gram. Rare and wondrous indeed.
Although Byakudan and Jinko get the most attention in Japanese incense, Hinoki should not be overlooked. Used for centuries to build imperial palaces, temples and Shinto shrines, HInoki is considered sacred to the Japanese. Durable and resistant to insects and rot, Hinoki has a beautiful tight grain structure and a lovely fresh lemon-pine fragrance.
Whereas Byakudan and Jinko are imported commodities, Hinoki is a Japan native. Tall and slow-growing, Hinoki is a variety of evergreen cypress that reaches heights of up to 115 feet and three feet in diameter at maturity. In an effort to prevent deforestation of old growth Hinoki, such trees can no longer be harvested in Japan today, so instead Hinoki is widely cultivated as a timber crop.
Hinoki is known to absorb toxins and possess strong antibacterial properties capable of resisting fungus, bacteria and viruses. It is often used as a natural air freshener in Japan. The fragrance release by Hinoki is know to both stimulate and relax the mind, calming and focusing the intellect while reducing stress and fatigue.
No discussion of Japanese incense woods would be complete without Tabu-no-ki. Often referred to just as Makko (incense powder), Tabu-no-ki isn't even a fragrant wood. But without it, many of the fragrant woods above would be difficult or impossible to form into an incense stick or cone.
In the production of incense, Makko refers specifically to Tabu-no-ki, the powdered bark of Machilus thunbergii, the Japanese Bay tree. This powdered bark forms the binder that holds the fragrant materials together and allows them to be extruded into sticks or formed into cones.
There are many reasons Tabu-no-ki is used as a binder in the manufacture of Japanese incense. First, Tabu-no-ki has four grades, with the highest grade being nearly odorless when burned. When combined with other fragrant materials, Tabu-no-ki is almost imperceptible, making it a perfect neutral base from which to build a fragrance upon. Second, Tabu-no-ki has properties as a burning agent that allow it to burn completely and consistently, ensuring uniform combustion of fragrant materials within an incense formula. Finally, Tabu-no-ki is water soluble, and when mixed with warm water becomes a sticky paste that easily holds fragrant materials allowing for simple extrusion or pressing into final incense forms.
In general, all Japanese incense is a mixture of fragrant woods, spices, and Tabu-no-ki as a binder. The higher the class of incense, usually the higher ratio of high-grade fragrant materials to binder, whereas lower cost incenses generally use a higher ratio of binder to lower-grade fragrant materials.