Everything Begins with a Precise "Mold"

The process of making Hasami ware does not start by kneading clay, but from an exceptionally intellectual stage that determines the product's final quality. This is the creation of the plaster "mold," which becomes the prototype for mass production.

There are craftsmen, known as "Kataya," who specialize in this process. Their job is to faithfully translate the designer’s drawings into three-dimensional reality.

Clay shrinks by 11% to 14% in the firing process. The mold maker must precisely calculate this shrinkage in advance and design a mold that is one size larger than the finished piece. Even a slight warp of the rim or the delicate curve of the foot directly influences how easy the final product is to use, as well as its beauty.

It is no exaggeration to say that the quality of the mold determines the quality of the product itself. It is in this first step that Hasami ware's identity emerges—not merely as craftwork, but as industrial products built on precise design philosophy. The fate of the thousands, or even tens of thousands, of pieces to be born all rests in the hands of a single mold.

Breathing Life into Clay: "Creating the Blank"

Once the molds are ready, it's finally time to move on to the "creating the blank" process where the shape of the pottery is formed. The main raw material for Hasami ware is Amakusa pottery stone, primarily mined in the Amakusa region of Kumamoto Prefecture. This high-purity pottery stone is finely crushed and purified by "clay specialists," turning it into clay, which is then transported to specialized workshops known as "blank makers."

At the blank maker's workshop, various forming techniques are employed depending on the shape of the product.

1. Slip Casting
This slip casting technique is used when creating items with non-circular, complex shapes, such as teapot handles or mug handles. Liquid clay, or "slurry (deisho)," is poured into the aforementioned plaster molds. The absorbent plaster pulls water from the slurry, allowing a layer of clay of a certain thickness to form on the inside of the mold. Once the timing is right, the excess slurry is drained out, leaving the piece inside the mold. Thanks to this method, even intricate designs can be efficiently and consistently mass-produced with uniform quality.

2. Machine Wheel Forming
For round pieces such as plates and bowls, the forming is done on a spinning wheel. Instead of shaping each piece by hand, the craftspeople use the power of machines to quickly produce uniform, circular blanks.

These shaped blanks are still soft and fragile at this stage. After being dried, they undergo additional finishing steps, such as smoothing the rims, before being passed on to the next stage at the "kiln."

Chemical Reactions of Flame & Glaze: Firing

Once the prepared clay bodies arrive at the kiln studios, the crucial firing process begins.

First, the shaped wares are fired at a relatively low temperature of about 900°C in a process called "bisque firing." This increases the strength of the clay, making it easier to proceed with painting and glaze application in subsequent steps.

After bisque firing, the surface of the ware is decorated with designs using a blue pigment called Gosu, a process known as "underglaze painting." Next comes "application of the glaze," where the surface is coated in a glassy layer to add durability and luster. This glazing process is the key to creating the wide variety of expressions that characterize Hasami ware.

One kiln craftsman shares their thoughts on glazes:

"Even after forty years in this craft, there is still much I don't know about glazes. Even with the same blend of raw materials, differences in placement within the kiln or subtle shifts in daily temperature and humidity can produce entirely different colors. It's truly like a living thing."

The color of the glaze emerges from chemical reactions: a high iron content can result in light blue or black, while copper creates a beautiful turquoise blue. Artisans, through decades of experience and countless tests, have learned the precise conditions needed to produce their desired hues, but in the end, they must rely on the unpredictable element of fire.

Once glazed, the wares are finally put through the "main firing." The temperature inside the kiln reaches around 1300°C, at which point the clay vitrifies into porcelain and the glaze melts, forming a beautiful glassy coating. In the past, craftsmen would vigilantly monitor the kiln day and night, adjusting gas pressure every three hours to keep the flames alive and observe the kiln's condition.

A Town as One Giant Workshop: The Strengths of Division of Labor

As we've seen, Hasami ware is created through a finely tuned division of labor between highly specialized craftsmen: mold makers, clay suppliers, body makers, and kiln studios. Each specialist trusts in those handling other steps and dedicates themselves to perfecting their own role. This entire town functions like one giant atelier—a production system that is the main strength and joy of Hasami ware.

This setup raises the level of expertise in every step to the highest degree, allowing for high-quality wares to be produced efficiently and in large volume. Back in the Edo period, it was this system of mass production that enabled delicately crafted porcelain—once a luxury good—to spread as inexpensive, everyday "Kurawanka bowls." Without such a divided labor system, that would not have been possible.

However, there are inherent vulnerabilities: if even one link in the chain loses its skilled workers, the entire supply chain is at risk of failing. This seamless relay of craft relies on every single participant, balanced on a razor's edge where no one can be absent.

Dialogue with New Technologies: Looking to the Future of Tradition

Recently, new trends have begun to flow into the traditional division of labor. Facing the serious challenge of declining successors, some makers are introducing modern technologies and trying to internalize processes. For example, one kiln studio is tackling the creation of prototypes for new products using 3D printers, making up for the dwindling number of mold makers.

This does not deny the value of traditional handwork. If anything, it's an expression of Hasami ware's resilient spirit—adopting new technology to carry forward core traditions rather than being afraid of change. For 400 years, the region has responded flexibly to changing times, never sticking to a single style. Once again, Hasami ware is searching for new ways of making in a new era.