Oil Spot and Hare’s Fur glazes belong to one of the most fascinating traditions in ceramic history. For a 1,000 years, potters have explored the magic of iron, which is the most important ingredient in these glazes. Despite being one of the most common elements on Earth, iron has exceptional properties for glazing and it is the single most important material to produce the mysterious landscapes of Oil Spot and Hare’s Fur glazes.
As many of you know, my work as a ceramicist revolves around research. I spend a great deal of time exploring different clays, glazes and firing methods, always searching for new ways to bring depth and character to a surface. Having recently completed a series of porcelain teaware pieces with Oil Spot and Hare’s Fur glazes, I wanted to share a glimpse into the history of this style, where a single material, iron, can create an entire universe within a bowl.
Inspiration: the legacy of Jian ware
Oil Spot and Hare’s Fur glazes have their origins in Jian ware, a remarkable type of pottery produced in the Fujian Province in China during the Song dynasty (10th–13th centuries). Jian bowls were typically made from dark stoneware clay and coated with iron-rich glazes. Their forms were relatively simple and subtle enabling one’s attention to focus on the glaze itself.
During firing, the iron within the glaze would transform in extraordinary ways, creating patterns that resemble falling oil droplets, streaks of fur, or deep night skies scattered with stars. These effects, known today as Oil Spot and Hare’s Fur, made Jian bowls particularly prized by tea drinkers. Centuries later, they remain a powerful source of inspiration for potters and glaze researchers around the world.
Iron: the pinch of fairy dust
For me, iron is one of the most fascinating elements in ceramics due to the surprisingly complex ways it can behave inside a kiln. As the kiln is fired, the iron within a glaze can transform repeatedly depending on speed of heating and cooling as well as the kiln atmosphere (reduction or oxidation). These subtle shifts can produce an astonishing range of colors and textures.
An iron glaze may appear pale blue, as in certain celadon glazes, or deepen into the rich blacks of Tenmoku glazes. Between these extremes lies an entire spectrum of greens, yellows, oranges, ambers, reds and purples as well as metallic tones of silver, rust or gold. Texture is equally varied: Some iron glazes form smooth, glassy surfaces, while others develop crystalline patterns, metallic matrixes, or silky, soft matte depths.
One of the most extraordinary historical examples is the Yohen Tenmoku tea bowls, legendary vessels in which the glaze reveals shifting constellations of blues, silvers and deep blacks. In these bowls, the glaze surface contains remarkable visual complexity. It is precisely this richness—the sense that an entire landscape, an entire universe, can appear within such a small object—that continues to drive my own research into Oil Spot and Hare’s Fur glazes.
A modern approach to an ancient technique
While my work draws deeply on the tradition of Jian ware, there are two important ways in which my process differs from that of the original potters. The first difference lies in the kiln. Historically, Jian ware was fired in enormous wood-burning kilns known as dragon kilns, long tunnel-like structures built into hillsides. These kilns could hold tens of thousands of bowls in a single firing. Because of their immense size, they heated and cooled very slowly. This gradual passage through certain temperature ranges allowed iron crystals within the glaze to develop and organize themselves, producing the characteristic Oil Spot and Hare’s Fur patterns.
Today, I work with a gas kiln, which is much smaller, faster and more precise than historical wood kilns. By carefully guiding the firing schedule, I can introduce controlled changes in atmosphere as well as holds at key temperatures. These holds allow my iron glazes to develop similar crystalline structures despite a shorter firing cycle. For an individual studio potter, this approach also makes far more sense both in environmental and practical terms. Traditional dragon kilns were efficient because they fired enormous quantities of pottery produced by numerous potters. At the scale of my small workshop, a carefully managed gas kiln allows me to achieve the same visual richness while being extremely fuel efficient and having greater freedom to experiment from firing to firing.
Porcelain: painting with contrast
The second difference lies in the clay itself. Traditional Jian ware was made from dark, iron-rich stoneware. In my own work, however, I chose to explore these glazes on porcelain clay from Limoges, one of Europe’s most renowned porcelain manufacturers. My porcelain body contains hardly any iron and fires to an exceptionally pure white. When I started researching iron glazes, I was instantly attracted to the striking contrast between the white porcelain surface and the deep, iron-saturated glazes used for Oil Spot and Hare’s Fur. Where the traditional Jian bowls glow subtly from within the confines of a dark clay body, porcelain allows the glaze to appear almost luminous against its elegant white surface. The effect can feel sharper, more dramatic—like ink against paper.
Because porcelain contributes very little iron of its own, I introduce the necessary iron through layered glazes. This gives me a great deal of freedom during the research process. It is much easier to experiment with variations in glaze composition than to reformulate an entire clay body. As a result, I’m able to explore many subtle variations of Oil Spot and Hare’s Fur glazes by interchanging and slightly modifying a palette of iron and wood ash glazes. I currently play with layers of five different glazes to produce small series of cups and bowls that each reveal slightly different patterns and textures.
The universe in a glaze
Even after centuries of study, the chemistry of iron in ceramics continues to fascinate scientists and potters alike. The transformations that occur inside a kiln are extraordinarily complex, and many aspects of these glazes are still actively researched today. For me, that mystery is part of the beauty. Each firing carries a degree of uncertainty, and each successful piece feels like a small discovery.
Oil Spot and Hare’s Fur glazes remind us that ceramics is not just about shaping clay with our hands—it is also about working with natural forces: heat, chemistry, gravity, atmosphere and time. And sometimes, when everything aligns just right, those forces leave behind something remarkable: a mini-universe contained within a single teacup.
I have set aside a few singular pieces from this latest cycle of work on Oil Spots and Hares’ Fur glazes. Each piece carries its own landscape of iron patterns, shaped by the slow choreography of heating and cooling. Below is a selection of available pieces, please enjoy and let me know if you have any questions.
