Bamboo Treatment - Boucherie Method

INTRODUCTION

Background

The quality of bamboo craftsmanship, is generally poor due to several reasons: bamboo used for construction is not mature enough, bamboo is not treated, improper handling, lack of connection materials and skills, inadequate tools, lack of finishing materials and lack of exposure to the different bamboo designs. Furthermore, though people are aware of the beauty and the strength of bamboo, they are reluctant to make permanent structures with it because they are scared of its non-durability.

It is because of this that we tried to find a solution to increase the durability of bamboo as a building material

MODIFIED BOUCHERIE TECHNIQUE

From the web resources we could get the general concept of the Boucherie technique, but we had to basically design and build everything on our own since we did not find a detailed manual on its construction. Everything in this plant was built and improvised by a local technician.

Physiological Characteristics
Bamboo culms are divided into nodes and internodes and are composed of two types of tissue; parenchyma cells and vascular bundles. The latter consist of vessels, thick walled fibers and sieve tubes and it is through these that water movement takes place in the living plant. (Rao 17) In Modified Boucherie Technique, (aka. sap displacement technique), pressurized preservative solution is applied on the basal end, which pushes the sap contained in the vascular bundle out and then replaces it with a preservative solution. This technique is only possible on a freshly cut bamboo because vascular bundle is still wet.

Equipments
1. A big cylinder, fitted with:
• A pressure gauge: The pressure inside the cylinder is always kept at 20-25 psi, which is enough to send the solution inside the bamboo.
• Solution inlet: a mixed solution is poured through this inlet.
• Solution regulator: it regulates how much solution is to be let out of the cylinder.
• Hand pump: a simple manual pump to put pressure into the cylinder. An electric compressor can be used if labor is expensive.
• Pressure regulator: to regulate how much pressure is to be let inside the cylinder.
• Solution outlet, which was later, split into 7 outlets, to let the solution out. See the fig.

Modified Boucherie Treatment Plant (Fig. 1)

A nozzle connecting bamboo. (Fig.3)

Nozzle: a closer look (Fig. 4)

Procedure:
This is a very simple technique, which can be operated by almost anyone. We have taken our treatment plant to the rural areas and more then 50% of the operators have been women.

Steps:

• The cylinder is ¾ filled with preservative. We are now using boron compound, and we are testing neem and cow urine.
• The cylinder is pressurized (up to 20-25 psi) using a simple manual pump.
• Valve in the nozzle is open for a split second to let the air out
• Nozzle is connected to the bamboo, which is made airtight using rubber tube.
• Sap starts dripping from the branch in almost 5 minutes. It takes about half hour for the preservative to come out from the opposite end)
• Treatment is done for atleast an hour so that the preservative can reach all parts of the bamboo.
• Bamboo is then stored horizontally in a rain-protected area till it dries.

Preservative:

• We are currently using Boron Compound, i.e. Borax, boric acid and water were used in 1:1:10 ratio.
• We have also used neem.

Results using Boron Compound:
Six months after the treatment, we found the following results:
• Molds were formed on the outside and the inside of the ends in almost all the bamboo.
• If the parts where molds were formed were split open, they were found to be clean and unaffected. Thus mold were only limited to the outside.
• Most of the bamboo had white termite like bugs, but they did not penetrate inside. They seemed to content living in the mold.
• 30% of the bamboo’s end where attacked by powder beetle, however they were limited only to the top ends. Only 6 out of 50 bamboos were infected inside. See Fig. 5

Example of an infected bamboo.(fig. 5)

Conclusion:
The reason most of the bamboo had mold in it is because they were not properly dried. They were dried in a closed environment, which had very little sunlight and air circulation. So a new kind of storage was built for another batch of treated bamboo, which had enough air circulation and sunlight yet they were protected against the rain (see Figure 6). In the treated batch the mold were not formed but they still had beetle infection, but yet again they were only in the top ends. It is not a big problem because during design and construction, by protecting the ends, we can stop the infection.

RESULTS USING NEEM

Procedure:
• ½ kilo neem was first boiled in 10 liters water for about half an hour. It was then cooled down; the result was a very thick black neem concentrate. However, it was very difficult to penetrate the solution through the treatment plant so the solution was again diluted at 1: 5 ratio with water.
• The solution was forced into the bamboo using boucherie treatment plant. The solution started coming out from the other end but not through the branches. The explanation was that vascular bundles are wider on the inner part compared to the periphery; therefore the solution could only penetrate on the inner part.
• The solution was then filtered to get rid of the particles, after which the solution easily penetrated the bamboo!

The experimented was successful in terms of penetrating the neem solution into the bamboo. The effect of the solution on preservation has yet to be studied. We are also planning on using cow urine because traditionally it has been used to treat wood.

ADVANTAGES USING BOUCHERIE TREATMENT METHOD
• The treatment plant can be locally and economically constructed.
• Our three treatment plant successfully treated 1200 bamboo in a month.
• Traditional treatment preservative can be used with this technique: for example neem and cow urine.
• It can be operated with a simple instruction by almost anyone.
• Since this can be taken to rural areas, it can be provide employment to the locals.
• It is a fast and effective process.

LIMITATIONS
• The treatment can only be done for freshly cut bamboo.
• It is only cost effective when one is treating more then 25 bamboo.
• Boron compound is not available everywhere, and the alternative like neem and cow urine have to be explored.

CONCLUSION
As per our objective we have found a simple and effective way of treating bamboo Modified Boucherie Technique. We have successfully treated more then 2000 bamboo using this technique and have trained many people in the process. If we get enough funding we will further explore neem and cow urine solution. However, with the success of the technique, we have already started design and construction in many parts of Nepal. After seeing the technique and our bamboo craftsmanship, more people are interested in using bamboo. Let bamboo prevail. Please check www.abari.org to see our projects.