Friday, March 9, 2018

Black Flowers: an interim report of my challenge to flower charcoal花炭

The Association of Niiharu Lovers 新治市民の森愛護会 has the Charcoal Baking Club. During winter, we cook charcoal 3 times from bamboos of Niiharu. I posted my first experience in the Charcoal Making Hut of Niiharu in February and March last year. Since then, I did a bit of research and found several variations that could be applied to our kilns for bamboo charcoal. This season I experimented with one of these alternatives in a fireplace. It is an interim report of my petit project to bake “different” charcoal, called Flower Charcoal, or in Japanese Hana-zumi 花炭. I don’t know if a fresh flower can turn into charcoal … what we call flower charcoal is made of acorns, burrs for chestnuts, torus of lotus flowers, … have you got the idea? They are not so substantial as trees or bamboos, but have a solid structure somehow. At times people call bamboo charcoals as flower charcoal when they are from bamboo trunks baked to be charcoal flower bases for a tea-ceremony room. (An example of charcoal flower base can be seen here.) Such as the flower bases of bamboo charcoal, flower charcoals are normally used for interior ornaments in tearooms. Since they are pitch-black, they are perfect for the color scheme of Japanese tea ceremony.

Niiharu’s hut for charcoal kilns

In theory, any vegetation will turn into charcoal, if enough heat is given for inducing self-combustion of the subject sealed in a space sans oxygen during a sustained period of time. For full-fledged daily use like cooking and heating, charcoal made of woods from broad leaved trees is the best. The finest quality charcoal in Japan, named Bincho-tan 備長炭, is made of Quercus phillyraeoides cooked for about 8 days by craftsmen who have accumulated traditional knowledge of Japanese forest life. In Japanese tea ceremony, charcoals made of Quercus acutissima in proper size is sliced and nicely put in a fireplace for teakettle. Tea masters demand meticulously defined forma and texture of charcoal for the “best tea ceremony.” In any case, charcoals of woods require several days of cooking, or industrial kiln with computerized temperature monitoring that is out of question for Niiharu Lovers. So, our kilns are for bamboo charcoals that demands less than 24 hour of firing-up before self-combustion. Comparing with charcoals of woods, bamboo charcoals do not have much energy when it is used for cooking or heating and will turn into ashes much sooner. Though, the bamboo charcoals have many tiny holes that can capture odor molecules, which is good for air and water purification. i.e. Bamboos have a structure with lots of holes bigger than woods. So I thought, if bamboos with lots of holes can turn into charcoal much sooner than woods, material-wise the more packed the texture is, the longer it is necessary for the time of baking charcoal. If the material is more fragile than bamboos, could it mean they are less dense than bamboos? If so, can we economize the time to bake flower charcoals? The answer for this question was, it seems to me, “NO.” Well, it’ll be easy for you to know from the photos how flower charcoals look like, and how my experiment went. I show you below how I cooked flower charcoals.

1. First, the material. I gathered cones of pines, cedars, cypresses, etc. from Kanagawa’s forests and put them in a can for paint. The size of this can was 1L, and the cones occupy about ¾ of it. Please remember the amount of cones I stored in the can. This is a wrong example.

2. I then located the loosely sealed can in a campfire which we made during charcoal baking session for the kilns.

3. Very quickly, steam came out from the gap between the can and the lid.

4. I left it for a while. Lots of steam gushed out. After 30 min. or so, the color of steam turned blue. It was a sign for the beginning of self-combustion.

5. At around 40 min. point, steam stopped.

6. I then took the can out from the fire and closed the lid completely. In theory, as long as the contents had enough heat it kept on self-combusting in oxygen-less chamber.

7. The can was left outside until it cooled wholly.

8. After cool-down, I opened the lid. The contents looked like this.

9. The product. They are flower charcoal, but this photo shows several problems of this approach.

The method I took above was a standard summer-camp procedure in Japan when kids make flower charcoal in campfires. Yeah, the charcoals made in this way are still pretty. BUT,

  • Could you see some cone charcoal had a collapsed shape? That’s because I became stingy and staffed too much materials in a can. In the cooking process, the steam pressured the crowded contents too much and the tops of cones collapsed. It’s bad.

  • Please look the inner side of the lid on the left in the final photo. It is coated completely by tar. After the water and other lighter elements came out, the heavier components of cones, such as phenol and lignin, evaporated as long as there was enough heat from campfire or self-combustion. However, unless the escape route was provided when the heavier components were cooled they turned into liquid, and then solid within the can which is the most visible on the inside of the lid. That’s the problem. The tar was left not only on the lid but dripped down on the flower charcoals themselves, which make the final product less than perfect. In a more close shot, they look like

this. It may be a matter of opinion … I found a kind of greasy texture in some parts of the charcoal. It’s surely not so perfect for OM of tea-ceremony room.

The senior Niiharu Lovers suggested 2 reasons for the result. First, I closed the lid completely when the visible steam stopped emitting. That’s because I feared leaving the can with a loosely closed lid in open fire could ignite the contents easily and turn them into ashes quickly. Though, it robbed the opportunity for the molecules to evaporate into the air after coming out during the self-combustion. The cooled tar-molecules coated the surface of the charcoal. So, I should have made the holes on the lid for letting the tar vapor escape even after tight closing. Second, I terminated the heating process too early. In order to get rid of volatile elements completely by evaporation, we need to sustain self-combustion in oxygen-less environment much longer while providing the exit for the tar vapors. The suggested solution was, it would be better cooking flower charcoal in the kiln. We could place paint cans with the lid with holes on the bamboos and close the kiln completely by cray. Then, let the standard baking process for bamboo charcoal work for the flower charcoals as well to turn them into a pure carbon while maintaining their pretty form. Hmmmmmmmmm. OK. That’s the homework I can try next winter. Come to think of it, although the cones or burrs feel fragile, at the molecule level they are similar to the woods. It can take time for the chemicals they contain to evaporate totally. 40 minutes of cooking could not do the job.

Though they are pretty, aren’t they?

Actually, there is another hurdle to clear to make this project better. I found collecting the material for flower charcoal took time. Say, we can place six 3L paint cans on the bamboos in a kiln. Let the cones and burrs occupy only 50% of a can, but it still is 9L. This year I have to be more strategic to gather the material for flower charcoal ... They might be a good product to raise fund for the activity of Niiharu Lovers …

Charcoal making is a task during the dead-winter.

When I did a research for flower charcoal, I encountered with articles from the research labo of Dr. Kazuo Akagi 赤木和夫 of Ritsumeikan University 立命館大学. Prof. Akagi refines the creation of solid polymer electrolyte fuel cell by expanding the mechanism of flower charcoal making. The successful way of creating flower charcoals preserves the forma of the material and transforms them into a pure carbon. Prof. Akagi wrote the methodology can be applied to create high-powered fuel cell. Wow. I now engage in the elementary procedure for fuel cell technology, don’t I. That’s … uber-cool.

If you find a problem in Niiharu Forest, please make a contact with

Office for the Park Greeneries in the North 北部公園緑地事務所
Yokohama Municipal Government Creative Environment Policy Bureau 横浜市環境創造局
Phone: 045-311-2016 (I guess in Japanese only)
FAX: 045-316-8420 (I hope there is somebody who can read English …)

Niiharu Administrative Office / Satoyama Exchange Center 新治管理事務所・里山交流センター
Phone: 045-931-4947
Fax: 045-937-0898

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