Tenmoku, a Japanese term referring to both a form of pottery and style of glaze, is thought to emulate the ancient Chinese stoneware from the Song Dynasty (1127-1279) called Jian Ware.
Tenmoku pottery, in stoneware or porcelain, refers to the beautiful utensils and possessions centered on the rituals of the Japanese matcha tea ceremony known as chanoyu. Its color of blacks, browns and persimmon tones became associated with the glaze technique as well as the tea bowl forms. These glazes were introduced in Japan in the 13th century by monks who promoted the practice of chanoyu. Later these objects became centered in the ritual and signified “suki” or one who keeps his tea utensils in beautiful condition. When the glaze formulas passed down through generations and began to be published, its use appeared on less ritualistic objects and became more familiar as the term for the glaze rather than the form.
First introduced widely in the west by the famed British potter Bernard Leach in his seminal 1946 book A Potters World, these glazes, patterns, techniques and formulas are a part of many modern potter’s finishing repertoire. Tenmoku is now considered a general term referring to iron reduction firing to achieve blacks and browns.
And while blacks and browns are historically associated with more ordinary and utilitarian ware, tenmoku pieces have a considerable depth and extraordinary melding of colors with a variegated richness. It has been compared to the culinary term umami, referring to balance of salty, sweet, bitter, and sour. The balance and complexity of an umami-like approach of colors are achieved through components of iron oxides, feldspar and wood ash. Amazing transformations occur in the kiln when the separating and vitrifying of the oxides on the surfaces of the forms streak, melt as feathery streams and form tortoise shell patterns often with persimmon pooling on the surface. The changes are elusive and not exactly repeatable. Other techniques like “oil spotting” or iridescent halos and other experimental firing techniques are achieved when the temperature is highly controlled to allow for iron oxide to liberate oxygen atoms that bubble to the surface of glaze and deposit black spots. These techniques, while formulated as recipes, render highly unique results that are truly one of kind.
The Scandinavian makers learned these techniques and tricks from the Asian masters via Bernard Leach and applied them to their new forms to achieve a completely new hybrid and genre of complex glazed pieces best understood as a grouped collection.