Bamboo preservation
Practical Action
Boucherie method
This method must be applied on fresh bamboo, the very day the bamboos are cut (or they can
be kept under water). Pressure is needed to press the preservative into the bamboo, and can
be created by an airpump, or a tower. In this last case a drum containing preservative is put
on a tower of 4 to 6m high and connected by tubes to the end of the bamboos (see Figure 2)
using cuffs (see Figure 3). At first, sap will drip from the low end with hardly any
preservative. As the process continues the concentration of preservative in this sap will
steadily increase.
This sap must be collected. It can be used again if preservative is added to achieve the
original concentration. The culm is ready when preservative in the original concentration
drips out the far end. This takes about one hour. Check this yourself: give the preservative a
colour from which you can judge the result, or use a piece of pH (litmus) paper to check the
concentration. Put the bamboos in vertical position in an empty drum to regain any surplus of
preservative from the culm. (Note: this method is not applicable to bamboos with thin walls)
Figure 3: Cuff to connect bamboo.
a. Entrance of liquid
b. Reduction of diameter (PVC)
c. Pressure-chamber, PVC, 100mm diameter
d. Exit of air, flexible plastic hose
e. Metal wrapping
f. Rubber sleeve
The economics of preservation
Generally speaking, a good (chemical) preservation can increase the natural lifetime of
bamboos to 15 years in the open and 25 years undercover. Unfortunately, very few data are
known about the price of preservation. The author has calculated from a real case in Africa in
1985 that preservation with Octabor in an open tank costs 30 per cent of the price of the
bamboo, which is certainly economic. The same ratio has been found in Costa Rica in 1994
with boron and Boucherie: the bamboo costs $0.36 per metre, and the preservation $0.13
per metre.
For an economic use of bamboo in building it is important to pay attention to sound
construction methods.
Termites
If the bamboo is likely to be attacked by termites, 1% Dieldrin added to the preservative is
effective. However, Dieldrin is dangerous, and use is illegal in several countries.
Note: the remaining preservative can be stored in a closed drum for another use in the near
future.
4