Thursday, June 19, 2008


Two natural stones under the electronic microscope

What was my excitement yesterday when the first images of two natural stones powder appeared on the monitor connected to a SEM (Scanning Electron Microscope)!

I had had the idea (more precisely the faint hope of a possibility) to observe stone powders under an SEM soon after I joined the institute where I am currently working here in Taiwan. The Industrial Technology Research Institute (ITRI) regroups many different labs specialized in domains as varied as material science, opto-electronics and medical instrumentation.

I had asked my friend Emma (more thanks to you Emma!) if she could arrange some time to observe the powder, but she had had so far a busy and tight schedule. But eventually the day came. I don't recall having seen many SEM images of stone powder, only 1 of which I am sure, in a Japanese book. And never had I had the chance to observe my own stones.

Before writing more, here is one of the image we saw. It is a black natural stone from Taiwan, which a close friend of mine estimates to be in the 10,000 to 15,000 grit when lapped with a diamond stone.

Taiwanese stone

Taiwanese black stone (grit ~10,000 to 15,000), 8000x



Japanese stone (Kyoto, honyama brand)

Japanese Stone from Kyoto (honyama brand, from Lee Valley) 4000x



60000x (notice the small holes?)

Stone powder preparation

I obtained the stone powder by simply lapping my stones with a diamond plate adding small amount of water. Both the stone and lapping plate were thoroughly rinsed with water prior to collect the slurry. The paste I got from the lapping process was then collected into a clean plastic container and left to dry.
The powder is then scrapped and deposited on a small metallic plate (which fits the SEM vacuum chamber) and covered with a thin, vapor deposited, layer of tin. The tin is necessary for non conductive material and it doesn't change the structure of the specimen.


Well I hope you can participate!
What stroke me the most is the that many particles appear like scale of a fish, as if some crystals in the stone had been cleaved. I wonder whether that is the action produced by the diamond plate. And that is what would provide the stone (particularly the Taiwan stone) a more pronounced cutting action.
Note also that on a larger scale (dimension), many natural sharpening stones can split into layers or strata. I wonder if the microscopic observation has any relationship with the mentioned property.
Further observations would be to look at the surface of the stone itself, that is flat and free from any slurry from the lapping plate. A whole stone will not fit in the SEM chamber, but I could break off a 1 or 2mm piece.
I would also be curious to observe a slurry in which metal particles are also included from a few sharpening strokes.
Also of course, I would love to observe different stones.
Now, let us make an analogy with planet exploration. If an imaginary earth observer was to point his telescope from a distant planet on the Gobi desert, he/she'd have a seriously biased idea of what earth is. Have you seen the scale of the photos? 1um to 20um... There is surely a lot more to be seen and discovered even for one particular stone.
And my friend said that a blade could also be observed...

The issue to these experiments is the cost. My friend accepted to do it for free the first time, but since her lab performs observations for other departments, it must charge the customer. The cost of using the SEM is about 80US$ per hour. An observation can be done in 30mn a the fastest, that is still some money that unfortunately I would rather spare for buying wood or for a trip to Japan.
If enough of you are interested in these observations, with each one sharing the cost, then let us decide of a stone to observe and conduct more observations.
One remark: with the SEM, we can not distinguish a chemical element from another, silicate from aluminum dioxyde...

Note on the images
I have no problem you copy these images and publish them elsewhere at the condition you mention their origin.

Wednesday, June 04, 2008


6 days in Japan

Reflexion of the sun on a copper foil used for roof restoration of the Inu Shrine

Daily work in a Japanese workshop

During this 6 days stay in Japan I have had the chance to work in Mr Sugimura's workshop. Mr Sugimura is a temple maker, also head and creator of kezuroukai.
What stroke me in the workshop, and I believe it is the same in most if not all similar workshops around Japan, was the cohabitation of modern electric machinery with traditional tools and instruments.

Tenons, at least those I have seen being cut in front of me, on beams meant for a house structure, are not with a hand saw but with a device (which I can not name) equipped with 4 motors and 4 blades, cutting in one single pass all sides of the tenons.

At the same time, these tenons and other markings are drawn with a sumisashi dipped into the ink pot of a sumitsubo. The later is also frequently used when it comes to draw straight lines on long beams, including round ones.

Marking tenons with a sumisashi

A sumisashi. They are made from the outer part of big bamboos, sold preformed and to be finished by the craftman.

Mr Mori's selfmade sumitsubo

An interesting tool is this power plane. The blade is fixed and the piece (big, otherwise small hand plane would be used) is carried on top of it. It is impressive to see in work, the beam on the photo is grasped and accelerates significantly before reaching the blade, then it stops at the end of the table and comes back in the hands of the operator. It happened that the pressure of the upper rollers was not enough and the beam continued its course straight ahead, of the nobody was at the other end to catch the beam back.
I used the machine and it is actually fairly simple to operate.
Shavings are checked to assess the quality of the planed surface: a continuous long shaving promises a smooth surface.
For an effective and tear free surface, care must be taken to send the beam ... foot first, with the head (atama) pointing toward the operator. Foot and head refer here to the tree as if it was standing. The head is marked with the sumisashi, if it is not then one has to observe the wood grain, knots are very helpful for this purpose.

Inu Jinja (dog shrine) restoration

The Inu shrine is located in Nagoya, Aichi prefecture. It was believed that the emperor Temmu (天武天皇) was harvesting rice in the area surrounding the shrine. Temmu was the 40th emperor of Japan, where he ruled from a.d. 672 to 686.
One of the main purpose of the restoration is to remedy to a decaying roof: replacing decomposing parts, replacing macadam paper with more durable cooper sheets. Against common belief, hinoki or its Taiwanese brother kuaimu (which made parts of the shrine) does decay, if it is left in a constant humid envrionment, such as under sheets of macadam papers. It could however be kept decennies if kept in water.

Coper smiths at work on the roof on the Inu Shrine

Kiso wood market

Kiso is a town in Nagano prefecture. It is a 100km drive from Nagoya.

All the wood sold at this timber market is kiso hinoki, the place where it is harvested gave its name to the wood.

It is different from the Taiwan closest relative, chamaecyparis obtusa var formosana and chamaecyparis formosensis. The smell is different, though somehow related, the kiso hinoki smell is lighter and maybe a bit more spicy than its two Taiwan brothers. Color is pale yellow as the Taiwan's closest relative.

Sunday, June 01, 2008


Kezuroukai in Takaoka

This Kezuroukai meeting took place in Takaoka, under a temporary (but immense) shelf to protect a boudhist temple under renovation (more details on the temple to come).
Kezuroukai means literally planing meeting, but besides the planning contest, many activities are organized. This meeting gathered craftman from various fields related to the temple renovation: sculptors, painters, wood turners, particular, ... and other more directly related to woodworking tools: a dai maker was present, as well as a "toishi master".

It has been several months since I didn't write. I am just back from a short trip to Japan, and am bringing back a lot of material to fill up a big post.
Topics which will be developed are:
These will probably be posted in several parts in the coming week.

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