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Mark Meckes
5th November 2001, 06:56 AM
The process using smoke to prevent insect infestation goes back many thousands of years, when villagers who built and lived in bamboo, and other types of houses with grass thatched roofs learned that the smoke from an indoor fire-pit prevented insects from living in the roof and upper
walls of the house, and also extended the life of the building. I saw these types of houses, which are still constructed this way in Papua New Guinea (and other countries) in the 1960's. ( they actually had no chimneys).
In Japan, old buildings that are being demolished (that have bamboo in the ceiling / roof structure) are sought after by bamboo artisans for their aged, smoked bamboo.

I have used a wood fire many times to heat cure bamboo, but the this method is different because it uses high heat as well.
This is done by moving the bamboo pole (or several at a time back and forth over the fire, and constantly rotating the pole until the surface coating of the pole becomes hot and slippery. Then at the right moment the waxy exudate is wiped off. Bees-wax can also be applied during the process, and any excess wiped off.
During this process if the pole is not hot enough, the surface will be very sticky and hard to wipe off.
I've tried this technique for smaller pieces, in an oven and the temperature seems to need to be around 275oF -300oF before the surface becomes slippery.
The wood fires I've used often have rising smoke,and during this process the pole surface may become blackened with soot, but most of the discolouration can wiped off when the surface becomes slippery.
If the pole is put back over the fire AFTER it has been wiped, it can get stained by the soot, which may be good or not-so -good depending what effect you desire.
A coal /briquette/charcoal fire is not as smokey.

A simple`smoke cured' technique is to put some bamboos poles at a further distance away from the fire for a period of perhaps several weeks to smoke cure them.

Mark Meckes
*******************
The following is from an email written by John Hamilton
July 2001 from The Original Bamboo Factory - Jamaica :

Recently we organised a workshop with the guidance of Linda Garland from Bali and Simon Valez from Columbia who have become frequent visitors to our shores .
The workshop got funding to bring a Columbian coffee/bamboo farmer called Gabriel who has been treating his Guadua by the Japanese smoking technique.
A delegation of Columbians visited Japan and were shown around the plant but had to figure it out themselves.
Well we're still in that process ourselves!
It seems that the Japanese have been using this technique for the last 600 years!! And not much of us elsewhere know much about it.

In simple terms you build a long coal skill using waste bamboo and channel the smoke through pipes into a bamboo constructed chamber filled with your culms ready to treat.
This chamber is covered in heavy gage polythene with a chimney at the far end and a zinc floor graduating to a gutter which helps collect all the condensation (pyrolic acid otherwise known as wood vinegar)
We smoked the bamboo for 2 weeks , having to refill the coal pit at least once.
At the end of the day we had not only produced smoked treated bamboo, covered in tar which we later scrapped off, but a good amount of charcoal which burnt well on the barbeque and added flavour to the chicken !

Having thought we had finally found the miracle treatment for bamboo, not so fast, our expectations have met another hitch when after 6 weeks in the shed, dust and insect attack raised their ugly heads again and much cracking too.

So its back to the drawing boards, and after a meeting with Mr Valez last month, he tells me there is another man which he gets his bamboo from who had also gone on the trip to Japan. He treats it upright and we believe the heat factor plays an important role.
The great mystery continues and I plan to visit Columbia soon and will keep you all informed .
Meanwhile can anyone help shed light on this process?
It is to be noted we are using Bambusa Vulgaris, the common variety here which of course has the highest starch level.
John Hamilton
Original Bamboo Factory Ltd.

bambooda
17th November 2001, 07:24 AM
The following is a translation of a document that I received from Darrel De Boer, a friend of mine and bamboophile. The translation was by another good friend Angel Sampedro del Rio of a document supposedly written by the guy who worked with Simon who designed the Zeri pavilion -
whew! Anyway, the following is the result:

Hello Cal,
I'm now reading the notes from Marcelo Villegas.
The thing is that in the jpg the characters aren't very defined, so for several words I have to guess and complete many gaps.
Something that caught my attention is the concept of no use hard toxics, and
use the "acido piroleņoso" as a insecticide. I don't know a standard English word for acido piroleņoso, but means a natural chemical that comes from the ignition of wood, contained in the smoke -I can try "pirolignin acid"
and he also mention the "wood vinegar" as synonime, but I'm not sure if that is the word. He also says that this acid is absolutely non toxic for humans and is also used to clean the digestive system.
This process make the culm protected against xilophage insects, improves the mechanical properties of the culm by "lignin solidification", improves the resistence to humidity and dries the culm.
The process -used for centuries by different cultures- consist by maintaining the guaduas inside a chamber full of smoke, in circulation.
The smoke comes from pieces of wood or guaduas.
The temperature and humidity is controled until the culms achieve 12% humidity.
In fact, vegetal charcoal is put at the bottom, and in the middle seems to be a container with water and this acid (F). The text isn't very clear for me, but I can see that the device works as an oven, but by evaporating the solution.
Then part of the vapor condensates in the walls of the oven
and is recovered in the J recipient.
Culms harvested 1 or 2 months ago, with 50% humidity, comes from the oven with 12% humidity and the diameter is reduced in 8% (10 cm initial diameter, 0.8 cm of reduction)
He mentions that they made several controled experiments, but nowhere says how long the culms are exposed to the smoke.
2 different experiments were to expose perfored septums guaduas and entire ones. The entire ones had 12% humidity in the skin-external layers, but inside remains about 30%. The result isn't good because they are about 20%
difference between outer and inner sides, creating big tensions and cracks.
With 1/8" (?) holes in the septums, the result is very improved, quite homogeneus.
Then he wrote about the microwave system, which heats first the inner part of the culm.
The time of exposure of culms into a comercial microwave oven is 40 seconds per gram (sic), allowing a anhydrus result. He says later that is the best system either for guadua and for wood.
In "Otros" (others) he mentions that a similar system is used in japan with a wide diffence of complexity, from the artisanal one, where the craftman heats wood dust and put the culms over it covered with "tents" to hi-tech computarized systems.
Then he mentioned a system where, in one hand is produced charcoal, and in the other dry guaduas. Not very clear for me again.
I can try to translate the references of the oven if you are interested.
In this part of the text, Marcelo uses several words from Columbia, not common here, but I can search them if you want.

Do you have Marcelo Villega's e-mail? Maybe I can ask him questions about details that you want to know.
Is a shame that he didn't mention the time of
exposure...Hours, days, weeks???

My comment is that this system could be quite different for the different bamboo species. I'd really like to try this method, but I live in a house and I doubt that Mariana and my neighbors allow me to do so.

Please allow me know your comments, apologize my English (maybe I invented several words, ask me if so) and the best for you.

Saludos
Angel Sampedro del Rio
Un Mundo De Bambu
http://usuarios.arnet.com.ar/bambu/

To my knowledge, Guadua apparently has a particular fiber structure that is resistant to splitting and generally more resistant to insect infestation than most other bamboos.
This is the variety used in the Zeri pavilion and apparently smoke treated as explained above.
My experience with B. vulgaris and close relatives is that it goes off the charts when it comes to starch content - which is what the bugs are after.
I've tried many different methods of insect prevention with
vulgaris and generally speaking it is difficult to achieve success.
My observation is that heat treatment, similar to what Mark Meckes has described, somehow tempers the wood of the bamboo, and makes it less susceptible to insect and rot damage.
I would suggest going through the archives of this discussion group as this topic has been discussed many times.

Cordially, Cal

Mark Mortimer
18th November 2001, 07:40 AM
Hi everyone,
Very interesting, this smoking subject. Any low-tech non-toxic
method of preserving bamboo for exterior use is extremely vauluable.
Just fouind the website for the photo: zeri's site, with picture of a smoking oven:

Edit: Link to site no longer works

Two observations: the size of the oven and amount of culms therein, and the two barrels on the top of the oven, function unknown.