Kishu Binchotan is not ordinary charcoal; in fact, it is extraordinary and unlike anything else. It presents various uses and applications owing to its unique properties. While I haven't explored all potential uses, it feels akin to a new material emerging from outer space. Given the multitude of producers claiming their products as Binchotan, let's find out what the Kishu Binchotan really is.

What is Binchotan?

Binchotan charcoal was originally developed by an anonymous charcoal maker in Kishu (now known as Wakayama) and later popularized by a local charcoal wholesaler named Bichuya Chozaemon (abbreviated as "Bincho") over 300 years ago. It is a specific type of white charcoal; however, not all white charcoal can be classified as Binchotan.

The Japanese Agricultural and Forestry Standards (JAS) previously categorized white charcoal and specified the requirements for the premium grade known as Tokusen. Within the Tokusen grade, the minimum hardness was set at 10, but only those with a hardness of 15 or above were recognized as Binchotan. This official standard was discontinued in 1997. Today, the specifications are voluntarily governed by members of Japan's fuel and charcoal associations.

Binchotan is distinguished by a refinement level ranging from 0 to 3, compared to the 0 to 4 scale used for standard white charcoal. This indicates a higher purity of carbon, which is one of the key characteristics that sets Binchotan apart.

Main characteristics of Binchotan:

• Made from Oak/Ubamegashi Oak
• Hardness: 15 or higher
• Purity of carbon: 0 to 3
• Bark-free
• Shell-pattern section view
• Metallic luster
• Produces a metallic sound
• No horizontal or vertical cracks

Hardness

Hardness is measured using the Miura Charcoal Hardness Scale, which is based on an alloy composed of lead, zinc, tin, antimony, copper, iron, and other elements. The scale is divided into 20 grades, with lead assigned a value of 1 and a copper-iron alloy rated at 20. Binchotan is required to have a minimum hardness of 15, and some specimens achieve the maximum hardness of 20.

This level of hardness is comparable to that of stainless steel, surpassing materials like aluminum and copper. I once attempted to drill a hole in a piece of Binchotan, only to witness the drill bit break off after minutes of strenuous effort.

Purity of Carbon

Purity of Carbon is assessed using the Charcoal Refinement Scale with a refinement meter, a device that measures the electrical resistance of charcoal by passing an electric current through it. The scale ranges from 0 to 9 in ten levels. Since carbon is conductive, higher degrees of carbonization (higher purity of carbon) result in lower electrical resistance. Consequently, a lower refinement level value signifies higher quality charcoal.

This electrical resistance is linked to the carbonization temperature. As the temperature for carbonization increases, electrical resistance decreases. Charcoal carbonized at around 700 degrees exhibits good electrical conductivity, and charcoal carbonized at around 1,000 degrees (white charcoal) further enhances electrical conductivity. This phenomenon is attributed to the carbon structure becoming more orderly as the temperature rises, approaching the structure of graphite.

Bark-free

Binchotan stands out for its absence of bark, a characteristic achieved through a meticulous production process. In the final stages of carbonization, when the smoke shifts from a clear blue to nearly colorless, a crucial phase known as Nerashi (or Arashi) begins. During this phase, the stoking hole is gradually opened, allowing air to enter. This causes the charcoal inside the kiln to shift from a dim red glow to a golden hue as the temperature rises.

This rapid increase in temperature efficiently utilizes the gas and bark of the Ubamegashi tree that has accumulated inside the kiln as combustion energy. It is a critical step that transforms Kishu Binchotan into a highly pure mass of carbon, a defining aspect of its unique identity. At the right moment, batches of charcoal are pulled to the front of the kiln. Here, the charcoal is thoroughly burned to eliminate any remaining gas or bark before being extracted from the kiln. This process is repeated until all the charcoal is removed.

The red-hot charcoal is then extinguished by sprinkling it with ash. This comprehensive process takes approximately 10 hours, constituting a full day's work for the artisans.

Shell-pattern section vIew, metallic luster, no cracks

What sets Kishu Binchotan apart

In Kishu, the Bincho kiln defies conventional wisdom by utilizing clay for its ceiling, even as it reaches remarkably high temperatures. This unconventional structure challenges the typical design of white charcoal kilns. The key lies in the ancient strata of the Kishu mountains, where highly refractory clay is scattered in various locations, allowing the construction of kiln ceilings with clay.

However, this choice comes with its own set of consequences. During the initial stages of carbonization, the ceiling becomes damp, slowing down the temperature rise. Yet, once carbonization is complete, the kiln cools efficiently due to effective heat dissipation. This creates optimal conditions for the production of high-quality charcoal in an efficient manner.

Attempting to replicate the Bincho kiln of Kishu proves challenging. The unique clay required for the ceiling is not readily available, compelling others to resort to using rocks. Consequently, even firing Ubamegashi in a kiln constructed with clay and stones fails to produce Binchotan charcoal comparable to that of Kishu.

Variations in Kishu Binchotan quality

While the variations may not be drastic, the quality of Kishu Binchotan charcoal can differ from kiln to kiln. These distinctions may arise due to various factors, including the materials used in kiln construction or the specific processes employed. For instance, differences may emerge based on the materials chosen for kiln construction, the timing of igniting Ubamegashi oaks inside the kiln after harvesting from the mountain, and other nuanced aspects of the production process.

Binchotan from other regions and countries

The expertise behind Kishu Binchotan from Wakayama has spread to various regions in Japan, such as Hyuga and Tosa, as well as to other Asian countries. Binchotan produced in China uses the same oak, including Ubamegashi oak, and is primarily used in Japan for commercial purposes, such as in restaurants. This is largely due to the shortage of domestic supplies and the cost-effectiveness of imported charcoal.

"Binchotan" from Southeast Asian countries like Indonesia, however, is made from mangroves rather than oak. Unlike traditional Binchotan, it does not produce a metallic sound when struck, diverging from one of the key defining characteristics of authentic Binchotan. Today, the absence of regulatory standards beyond voluntary guidelines has led to significant variations in the characteristics and quality of Binchotan available on the market.