Senko (incense stick) (線香)
The term "Senko (incense stick)" refers to the product which uses, as materials, various substances that emit fragrant smoke and fine aroma when lighted and is produced through the process of grinding materials, kneading, molding into the shape of slender sticks or coils and drying. Senko is a kind of Ko (incense) products.
Summary
Among Ko products, a product which is produced through the process of kneading materials and molding them into a stick and is "slender like a line" is specifically called Senko. A kind of Ko products called Renko, with a shape similar to a pill, is not so dried as in the case of Senko. The reason why its shape is fine and long is to make the burning time longer and stabilize the emission of the aroma. Also, it is easier to handle since burning is stable. Coil-shaped Senko which was developed with the aim of extending burning time is also seen. Coil-shaped Senko is divided into those developed for the purpose of enjoying aroma and those developed for meeting practical need for extending burning time, such as mosquito repellent Senko (=>Kayariki [mosquito repellent Senko holder]).
In Japan, Senko is generally used as the altarage for graves or Buddhist altars. Though it is not clear when Senko was introduced into Japan, it was the Edo period when Senko became prevalent among ordinary people. In recent years, Senko is also used in a room as the deodorant or aromatic as well as for the purpose of healing since Senko with floral scents or perfume scents have been introduced.
In the Edo period, Senko was also used as the substitute for a clock. At Zen-sect temples, time consumed until a stick of Senko burns out (about 40 minutes) was called Icchu and it was used as the unit time for Zen meditation. Similarly, the burning duration of a stick of Senko was used at licensed quarters as the standard of time for an amusement, but some prostitutes intentionally snapped Senko while burning and shortened the time.
Categorization based on materials
Senko is categorized into "aromatic Senko" and "cedar Senko" according to respective materials it's made of.
Aromatic Senko
Aromatic Senko is the product which is made of powdered bark of Machilus thunbergi together with the powder of fragrant woods such as the sandal tree and agalloch, other perfumes, charcoal powder and other materials and is produced through the process of kneading, molding into the shape of stick and then drying.
Cedar Senko
Cedar Senko is the product which uses, as materials, cedar leaves that were powdered by a crusher or a water mill after drying for about three months and is produced through the process of kneading with hot water and paste added, molding and drying. Cedar Senko is used when visiting graves.
Categorization based on shapes
Based on their shape, Senko is categorized into commonly-used stick-shaped Senko (綫條香 in Chinese), coil-shaped Senko and bamboo Senko. Further, though it is not called Senko, there exists a kind of incense with a conic (cone) shape that is produced from the same materials.
Coil-shaped Senko
In Hong Kong and Taiwan, people often pray with coil-shaped Senko, which is called "盤状香 " in Chinese, hanging at temples. Some large-sized ones continue to burn for nearly one month. As it is molded by winding thick and long sticks, its molding method is different from that of mosquito coil which is stamped in the shape of coil.
In Japan, coil-shaped Senko is sometimes used in order to keep incense burning throughout a funeral (vigil etc.). The origin of the above was the fact that relatives and other related persons used to keep vigil in turn in order to address persons calling to express condolence. Although such practice has declined recently, undertakers often recommend to keep candles and incense burning throughout the night and this type of Senko is used for the purpose of keeping incense burning while people concerned are sleeping. Coil-shaped Senko burns slowly and it takes about 8 to 12 hours for a piece of coil-shaped Senko to burn out. As contemporary houses are airtight, ventilation is required from time to time in order to avoid being smoked by Senko.
Bamboo stick Senko
In India, People's Republic of China and Taiwan, bamboo stick Senko (竹枝香 in Chinese), which is produced by attaching wet Senko around shaved bamboo, has been used from long ago. It is often on sale at import shops in Japan. Its production technique was imported into Japan in the Tensho era and became the origin of current Japanese Senko. The advantage of this type of Senko is toughness and in China, people often swing it so that aroma spreads out.
In Japan, it is also on sale at toy shops and/or mom-and-pop candy stores and sometimes used for other purposes than the primary purpose, such as lighting fireworks.
Bundled Senko
Bundled Senko means Senko bundled usually with paper. As this type of Senko is used when visiting graves, it is also called Yasenko (field Senko) because it is used outdoors. When lighting, untie a bundle, hold sticks in fan-like fashion and ignite them with a candle etc. There is also a case: a bundle is divided into small chunks and given to relatives after it's ignited, then each of them present the Senko on the incense stand.
As modern houses are designed to maintain air tightness in order to improve the efficiency of air-conditioners, Senko which emits less aroma and smoke is mainly used inside houses. By contrast, Senko which emits more smoke and aroma is mainly used outdoors.
Sanitary Senko
In China, Senko of a fat stick shape or coil-shaped Senko, both are called "衛生香 (fragrant incense)," is often used at public restrooms for the purpose of emitting aroma and getting rid of noxious insects. It is different from mosquito repellent Senko used for killing mosquitoes.
General production process
The following are the production process of "aromatic Senko" in the shape of a stick.
Whip powdered bark of Machilus thunbergi thoroughly together with the powders of fragrant woods and other perfumes, add hot water and knead.
Mold clay-like material (neridama) into sticks with same thickness as what extruders produce for exclusive use.
Put them on wooden boards (tray boards) and take them to the boards for drying (drying boards).
Line them up on drying boards in order and cut them into equal lengths.
Dry them for a week to 10 days and pack them in boxes.
Materials
The following materials are often used for producing Senko.
Machilus thunbergi
Sandal tree
Cedar
Agalloch
Mugwort
Sweet flag
Rose flower
Lavender
Famous Senko producer
Nippon Kodo
Kyukyodo
Kokando
Shoeido
Baieido
Kameyama (candle producer)
Famous Senko production centers
Awaji City (former Ichimiya-cho, Tsuna-gun [Tsuna-gun, Hyogo Prefecture], Hyogo Prefecture)
Production commenced in 1850 introducing the Sakai technique. Its Output of Senko became the largest in Japan during the mid thirties of the Showa era and current output accounts for 70% of total output in Japan.
Nikko City (Tochigi Prefecture)
The city has been famous for cedar trees called Nikko Suginamiki even before cedar trees were planted around the nation and its output of Cedar Senko is the largest in Japan.
Kyoto Prefecture
Thanks to the commercial value of products supported by the cultural background, its output of high value-added products, in terms of the proportion of production volume versus production value, is the largest in Japan.
Sakai City (Osaka Prefecture)
It is believed that Japanese Senko production was originated by a medicine merchant of Sakai who visited Korea during the Tensho era (1573 - 1592), and introduced the production technique and started production. Its output accounted for about 60% of Japan's total during pre-war period.
The status of production in Japan
Nationwide production volume and production value in 2006 was 7,315 tons and 31.3 billion yen respectively. (Industrial statistics • individual item section) Both production volume and production value peaked in 1995 at 10,859 tons and 35.1 billion yen in 1997 respectively and has been declining since then. Some of big producers have already shifted their production bases abroad. It is assumed that the volume of products imported from China, Malaysia, Taiwan, India, Vietnam, Thailand and Indonesia, including those produced at Japanese owned companies, is equivalent to nearly a half of domestically produced products. In the Kanto region, imported products account for 70% to 80% of the market of cheap Senko used for grave visits. In Tochigi Prefecture, one of principal production centers, many producers whose products are in competition with imported products were forced to cease business. By contrast, high-grade products have not been affected so much since the quality of import products is inferior. Domestic market has been increasingly divided into a market of middle-grade and high-grade products in which domestic products are prevailing and that of low-grade products in which import products are prevailing. A small quantity of products are exported to the U.S, Korea, Singapore, and Europe. In particular, demand for Senko is increasing in Germany where "Zen" is booming.