PRODUCTION IN KISHU REGION, WAKAYAMA PREFECTURE AND TOSA REGION, KOCHI PREFECTURE
Binchotan coals are activated coals produced in Japan's southern Wakayama Prefecture, or on the neighboring island of Shikoku in Kochi Prefecture. The term “activated” refers to a very specific manufacturing process: to make coals, of course, you have to burn wood, but obtaining activated coals is a much more complex operation. Details are given below.

petite île à Wakayama -small island in Wakayama Petite île à Wakayama - small island in Wakayama

Bateau de pêche à Wakayama - fishing boat in Wakayama Bateau de pêche à Wakayama - fishing boat in Wakayama

Port de pêche à Wakayama - fishing port in WakayamaPort de pêche à Wakayama - fishing port in Wakayama

The mountainous areas where Binchotan is produced are densely forested. Because of the hilly terrain, a highly varied arboriculture has developed here, and these regions are known throughout Japan for their citrus fruits and plums.

Collines de Wakayama - hills in Wakayama Collines de Wakayama - hills in Wakayama


Route des montagnes à Wakayama - Mountain roads in Wakayama Route des montagnes à Wakayama - Mountain roads in Wakayama

Case du producteur de charbon - house of charcoal producerCase du producteur de charbon - house of charcoal producer

These hills are also home to the Ubamegashi oak, a medium-sized tree with extremely hard, dense wood that sinks when immersed in water. It has been exploited for millennia by a handful of silviculturists who manage the forest and produce, from its wood, the most renowned charcoals in the whole of Asia.

Ubamegashi, le chêne de Wakayama - Ubamegashi, oak tree from Wakayama Ubamegashi, le chêne de Wakayama - Ubamegashi, oak tree from Wakayama


THE PRODUCTION PROCESS
ubamegashi wood is cut into long, relatively thin logs, which are straightened by adding wedges. The wood is stored for some time to dry. At the end of the drying process, the logs are placed vertically in an earthen kiln and the fire is lit. Two phases then follow.

1. The carbonization phase:
The wood burns slowly at low temperatures (around 400°C) for several days. The wood is thus slowly transformed into charcoal.

Tas de bois de chêne pour la production de charbons binchotan -  pile of oak wook for the production of binchotan charcoals Tas de bois de chêne pour la production de charbons binchotan -  pile of oak wook for the production of binchotan charcoals

Four pour la production de charbons binchotan -  Oven for production of binchotan charcoalsFour pour la production de charbons binchotan -  Oven for production of binchotan charcoals four pour la production de charbon binchotan - Oven for the production of binchotan charcoals Four pour la production de charbons binchotan - Oven for production of binchotan charcoals

2. The activation phase :
After a few days of carbonization, the kiln door is opened, allowing air to rush in and fan the flames. The temperature in the kiln then rises considerably, reaching over 1200°C. This is the activation phase.

Producteur de charbons actif binchotan au travail - producer of binchotan charcoal at work Producteur de charbons actif binchotan au travail - producer of binchotan charcoal at work

Charbons actifs binchotan sortant du four - Binchotan activated charcoals comming out of the Oven Charbons actifs binchotan sortant du four - Binchotan activated charcoals comming out of the Oven

Refroidissement des charbons - cooling down charcoals Refroidissement des charbons - cooling down charcoals

Détails du charbons actif binchotan - details of binchotan activated charcoalsDétails du charbons actif binchotan - details of binchotan activated charcoals


WHAT HAPPENS DURING ACTIVATION
The tars contained in the pores created during the carbonization phase will volatilize under the effect of the intense heat, forming a very large exchange surface, corresponding to around 1000m² per gram of coal! It is these substance-free pores that give coals their adsorption capacity.

Schémas explicatif de l'activation des charbons binchotan - explaination of the activation processSchémas explicatif de l'activation des charbons binchotan - explaination of the activation process


ADSORPTION, THE PHYSICAL PRINCIPLE BEHIND ACTIVATED CARBON PROPERTIES

Principe de l'adsorption - Principle of adsorptionPrincipe de l'adsorption - Principle of adsorption

Adsorption (not to be confused with absorption) is the phenomenon whereby molecules suspended in a liquid attach themselves to the solid surface with which they come into contact.

It's a principle very commonly used in industry in certain devices using activated carbons to capture various compounds, and decolorize or clarify liquids such as beer, for example.