Clay of Asahiyaki
Asahiyaki has insisted on employing clay deposited solely within the Uji region for generations. Previous to the Meiji era, this clay mined from Mt. Asahi and the kilns were originated from the name. Presently, the clay are taking from the Shirakawa and Mt. Orii where most of the area are covered with tea gardens, located on the opposite side of Mt. Asahi. The clay may be said to constitute the life force of Asahiyaki and it is derived from a layer of sediment deposited in distant antiquity by the Uji river. The mined clay is left for aging over a half century before use. The clay used for the pottery now is what the ancestors excavated, and the clay collected by present generation is laid to weather for the grandchildren.
This local clay is distinguished by a soft expression, a high degree of water absorbency and a low level of heat conductivity, these characters make utensils heat-resistant property. Therefore greatly suited to fashioning ideal tea utensils, "Utsuwa". This clay will respond to frequent use, by slowly changing in the way that enhances its attractiveness and interest. Among tea practitioner, such transformation is termed, “habituation to the hand” or “Nare ga kuru”. And Asahiyaki regarded as only 80% completion when it leaves the kiln, the rest 20% will be brought as a result of subsequent human handling.
Asahiyaki is divided into three categories by the firing process..
○ Kase / Fawn spot
Featuring a complex gradation of light yellow and gray character. A spot pattern like a deer's back is one of its features.
○ Hanshi /
Warm hearted orange like the morning sun is its feature, the color changes as much as use.
○ Benikase / Red fawn spot
The higher the proportion of iron in the clay, the more the hue of transparent-grazed areas change reddish-black than Kase.
The above categories using transparent glaze, have always been fired positioned in the lower temperatures of the kiln, create a beautiful color and natural clay taste. Asahiyaki also produce "Utsuwa" glazed formulated with natural ash glaze. They has been firing for a long time in a place where it gets higher temperature in the kiln. Subtle differences in the constitution of such ash glazes have distinguished the products of successive generation of kiln masters.
Ash glazes mainly use at present
○ Matsubaiyu / Pine ash glaze
It is characterized by a greenish coloration due to iron of pine. Whenever the sloping kiln is employed, the fuel used the split red-pine logs. The ash results from such firing is to create this particular glaze.
○ Geppakuyu / Moon white glaze
Those that had a purplish mottled due to copper coloration on the blue white clay of the moon white glaze were called "Kinyo" ,which had been keenly studied by Hiroshi, the younger brother of the 15th kiln master. Because Hiroshi passed away at the young age of 35 years old, his research was continued by the 14th and 15th kiln master, Hosai. Their successor, the present 16th Hosai is studying the technique of triple layered surface (natural clay, white clay and blue white glaze) coating the white clay over the basic blue white glaze. As being learned by "The History of Asahiyaki", in the late Edo period, Chobei Ⅷ of Asahiyaki has perfected a line of ware that met the needs of infused leaf tea (Sencha). During the era of the founding kiln master, there was no techniques for firing porcelain in Japan, and its technique originally in China was taken into Asahiyaki from around Chobei Ⅷ. Nothing better counterpoints of an infusion of green tea than the sheer pallor of porcelain clay itself. And appropriate glazing only enhances this effect. Asahiyaki has been studied to strive to develop original glazes that may even more vividly coloring the characteristic beauty of porcelain ware.
Glazes for porcelain clay
Copper based glaze, characterized by a deep oxblood hue
Pale blue-green vitreous glaze of notable transparency
Glaze distinguished by its delicate yellow tint
Powerful purple glaze
Deeply resonant dark green glaze
Bright and vibrant green glaze
There is few other kilns produce both clay-based ceramics and porcelain ware in Japan. This scarcity is due to the fact that these two types of pottery are different not only from the nature of the clay and also its culture we have been walking with. Thanks to the regional involvement, Asahiyaki has found itself simultaneously meeting the quite distinct ceramic needs of both the Rite of Tea and the leaf-tea culture, Sencha. Its success have been achieved largely to its capacity to respond the aesthetic demands in both fields.