Sesame seed effect on bamboo culm surface

[bambooda]

In Japan a bamboo surface that is highly valued is what they call "Misudake" or "Sesame seed bamboo".
It is the small bumps that appear on the skin of P. aurea when it gets too old.
I have a theory that there is an endemic virus or something in the bamboo that is kept in check when the culm is vigorous, but starts to show up when the culm is past maturity or dying. I think the immune system is failing at this
point and the virus begins to produce these bumps in the skin.
I use this bamboo in some of my work for it's decorative value, but only in non-structural applications as it tends to be very brittle and will suddenly snap in half under stress.
What the Japanese do to get around this structural malady is to cut the top off (branches & leaves) of a healthy, mature culm and wait a year to harvest it. At time of harvest the bumps have covered the skin, but the structural strength of the culm remains intact.
Anybody out there know what REALLY produces these bumps?

Cal

[Mark Meckes]

Hi Cal,
I too have noticed that this `Sesame Seed'effect is best produced from culms that I have harvested from a grove, where the culm has been left in place until it becomes beige.
Observations harvesting from a wild grove are that, as you mentioned, the longer it stands, the more brittle it becomes.
It seems that this effect is produced by a microbiological activity just under the waxy surface which produces the`Sesame Seed Effect'.
These `seeds' often surface in straight rows, along fiber lines.
Perhaps the sugars between the fibers provide substance for their formation, and the flowing air around a dying culm keeps the sugars `fresh' and palateable for the microrhizos (sp).
If the bamboo is collected soon after this appears the
bamboo is quite strong, if the inner wood is still an ivory color and not greyish.
I like using these pieces for many items from jewelry onward.
Picture:
http://www.bamboocraft.net/workshop/data/2/thumbs/1MVC-061F.JPG
Sesame Seed Effect (http://www.bamboocraft.net/workshop/showphoto.php?photo=544)
on Phyllostachys heterocycla cv Pubescens (Moso).

http://www.bamboocraft.net/workshop/data/2/thumbs/1MVC-062F.JPG
Close-up of Sesame Seed effect (http://www.bamboocraft.net/workshop/showphoto.php?photo=545)
This was a partially mature culm the died in the grove at Avery Island LA USA.
Many of my Phyllostachys spp. can produce this effect, and probably other genera as well.

Mark

[bambooda]

Mark,
Outstanding detail shots! What camera are you using? Macro lens?
I harvest in the wild so it is not easy to experiment much in the groves.
Since you have your own groves, would you be interested in trying the "topping" experiment to see if you can produce the sesame seed effect?

- Cal

[Mark Mortimer]

Dear Cal,
Angel and I have talked about this quite often and we reckon that the sesame seed effect can also be produced AFTER harvesting. I harvested a load of Aurea once, and through reasons beyond my control, stored them in a damp
place. A few months later most of them had the sesame seed effect, to a greater or lesser degree. I have no photos but I think it is the same effect as mark's photos. I will try to directly scan the surface of a culm and send it.
Regards, Mark

[Mark Meckes]

Hello Mark Mortimer/Cal,
The 'Sesame Seed' effect can be produced to varying degrees by storing harvested poles in humid conditions,
but I don't think that the quality of the inner wood is as good as when done standing intact in the grove.
Perhaps it needs better air circulation?
With either method it's a matter of catching the process at the right moment.
There are many variations of this effect.
I would be interested in experimenting with the topping/de-branching method to create this effect.
I think the time of year to do this would be important as temperature and humidity would be a big factor.
Any suggestions?
I also remember reading somewhere about using a mixture of mud and acid? brushed on to the culm.
Anyone heard about this?

Mark

[bambooda]

Hi Mark,
The description that I got of the topping technique came from a member of the Kyoto Bamboo Business Association.
They are an organization of people who are involved with all phases of bamboo production from growing - harvesting - processing - retail/wholesale of raw materials - manufactured items - hand made items - art - and the promotion of their
products.
The amount of information that is held within this group is
nothing less than awesome and seems somewhat like the guilds of past ages.
Like a guild, the information stays largely within the group and very little if anything is documented. Since much of the art of working with bamboo is experimental I can see how this might be the case.

This being said, I did stumble accross a small reference to the sesame seed technique in "Bamboo" by Austin, Levy, and Ueda - ISBN 0-8348-0048-9. Pg 207-8
"These patterns can be engendered artificially. The variety known in the East as sesame-seed bamboo is produced by cutting off the upper parts of the culm and sawing halfway
through the base in spring. This so weakens the remaining bamboo that fungus breeds vigorously on it until the culm is cut, decorating the entire surface with small black spots."

> I also remember reading somewhere about using a
> mixture of mud and acid? brushed on to the culm.
> Anyone heard about this?

In the same book there is this said in regards to the acid treatment -
"A pleasing and irregular pattern of brown spots on the yellow background may be permanently applied to square - or any - bamboo through artificial means.
A solution known as chemical mud is painted on the culm with a brush. Chemical mud is made from 2 parts of a clay
and water slurry plus 3 parts of 60% sulphuric or hydrochloric acid.
A design of definite form may be produced if the white waxy powder which occurs on the culm at this stage is carefully removed and the mud then painted on.
A stencil may be used if desired. - the chemical solution
should be washed off before the drying process.
The culms are washed, using chaff and brushes; the nodes are given a scrubbing with a coarse brush made out of the small branches of bamboo.
After the culms are dried, the oil should be removed and any curves straightened.
With square bamboo, it is even more important to remove all oil in order to preserve good color."

The context of this statement is that this is done when the culm is in the process of being "squared" using wooden
forms so I am assuming the application of this acid process takes place when the culm is young.

-Cal

[Mark Meckes]

Cal,
Thanks for this valuable information!
This past winter, an ice storm here in Austin, Texas broke off the tops of some of our 1-2+ inch diameter Phyllostachys aurea culms, at about 10-15 feet above ground level - at the position where the P. aurea nodes suddenly become compressed and distorted.
This was the stiffest part of the culm - with the least amount of flexibility. Compressed nodes near the ground didn't have this breakage problem.
Before I head down the road, back to my nursery in
Pennsylvania tonight, to dig up my bamboo, and close down operations, I'm going to tip-toe out into the vigorously shooting grove of Phy aurea and partially cut the base of 10-20 of these culms.
Most appear 1-3 years old.,
I'm glad nature did the topping for me.
I wonder if the topping procedure would (normally) be done just before or after the shoots rise?
I will let you know how the culms turn out.
These culms that I will be experimenting with are deep
in the heart of a 2 acre grove, deep in the heart of
(Austin) Texas.

Mark