As promised, this would be the post about the manufacturing process of CHAARQ. Just a bit of history: the manufacturing process was first pioneered by a charcoal (tan or 炭) maker in Tanabe, Wakayama prefecture, Bichuya Chozaemon (備中屋長左衛門) in late 17th century. In fact, binchotan was named after him, taking the first kanji character of his first and last name and adding the word “tan” which stands for charcoal in both Chinese and Japanese.
From here on, it is more like a science lesson, so let dive into it!
Outline of the manufacturing process
Harvesting ubamegashi
Pre-treatment of ubamegashi
Carbonisation phase
Activation phase - "Seiren" technique
Post-treatment of binchotan
1. Harvesting ubamegashi (oak)
This oak is extremely hard with tight grain (unlike normal wood that floats, ubamegashi sinks in water) unlike other trees. Since I am not a botanist, I would not go into the details, but it is worth mentioning that this oak was first harvested in Kishu (now known as Wakayama, where the best binchotan are produced).
2. Pre-treatment of ubamegashi
Harvested ubamegashi will be cut into long and thin logs (as shown below) and straightened by adding shims/wooden wedges. It will be left in the shed to air dry for a couple of weeks or may be inserted to a low-temperature kiln to shorten the drying process depending on the weather.
3. Carbonisation phase
Once deemed dried, the carbonization phase will take place. The logs will be placed vertically into a clay kiln (see how it looks like inside and outside) lit by fire and baked at a temperature of around 400°C for a few days. In this phase, the logs will slowly transform into coal/normal charcoal along with the formation of millions of microscopic pores on its surface. Tar would be the by-product in this phase and occupies the spaces within the microscopic pores. At this point, the full potential of ubamegashi is not realised and commonly, this is the phase where the run-of-the-mill charcoal (from other types of wood) would stop at.
4. Activation phase
To maximise ubamegashi's potential and obtain superior quality binchotan, the tar needs to be removed. This is where the activation phase takes place and the "Seiren" technique is deployed. It is achieved by allowing fresh air to gradually flows into the kiln (a picture of the firing kiln is shown below). With air (or rather just oxygen), it causes more intense combustion, and the temperature will escalate between 1,000 to 1,200°C. Tar that was once clogging the millions of pores are now volatized and the charcoal becomes denser, harder, with higher pure carbon content. In other words, it gets “activated” (1 gram of binchotan corresponds to 250 square metres of physical exchange surface area!). As this phase is delicate, any miscalculation/mistiming will turn/ruin the entire batch of binchotan to ashes, thus, it can take up to a couple of days to reach the desired temperature.
5. Post-treatment of binchotan
Once taken out of the kiln after the activation phase, while it is still red hot, it is smothered with a mixture of soil-mixed wet ash to cool them down gradually. It is exactly this smothering process that binchotan gotten the moniker “white charcoal” (see below for a picture of an unwashed, unbrushed binchotan). As mentioned earlier, activation phase is a technique ("Seiren"), so, the skill of the craftsman determines the percentage of carbon found in the charcoal. The higher it is, the better the quality. Typically for binchotan, the purity is around 95% while common charcoal can range from 60+% to 75%. If you had kept track of the time taken, a batch will easily take more than a couple of weeks to materialise. To all ethical binchotan craftsman in Japan, this is an art-form that is certainly worth to be celebrated and preserved!
I hope the above provides a glimpse on the manufacturing process and just in case you are still having doubts on this art-form and the fruits of these artisans' labour, in 2018, Blancpain, a famed 390-year-old Swiss-watchmaker used binchotan (shown below) as their Villeret Métiers d'Art collection watch faces. We may be wrong, but we see this as a tribute to an art-form probably as long as the history of the watchmaker. You can find out more on Blancpain's website and have a look at the abovementioned watch below.
Image source: Robb Report Singapore
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