Bamboo preservation
Practical Action
Chemical treatments
Many chemicals are used as a preservative for wood or bamboo. We will deal with the most
common.
CCA (copper-chrome-arsenic composition, in the proportion 3: 1:4) is good for timber, but not
for people. CCB and CCBF are better! (B = boron). Its commercial names include ASCU.
The concentration of the solution in water (%) should be approximately the same percentage
as the retention (as a guideline only), i.e. how many kilos of dry chemicals remain in Im3
bamboo after treatment:
• in contact with atmosphere and soil: 8 (to 12);
• in contact with atmosphere, not soil: 5 to 8;
• under cover (trusses, purlins): 4;
• undercover (ceiling, etc.): 3.
Method: modified Boucherie process (i.e. with airpump), lasting as many hours as the
percentages of retention and concentration (this again is a rough guideline).
Precautions
Most preservatives are toxic! Avoid contact with your skin. Wear gloves for handling the
preservatives and treated bamboos, as long as they are wet. Anyone who drinks CCA or
Octabor should drink a lot of water (milk is even better) and be forced to vomit (put your
fingers down his or her throat) at least three times. Consult a doctor as quickly as possible;
take a package of the preservative with you and show it to the doctor.
Boric acid, borax and boron are cheaper than CCA and less poisonous. For boric acid and
borax the commercial names include Octabor. The concentration of the solution is 2.5 per
cent each, to be dissolved in hot water; the retention, for use under cover only, 5kg/m3.
For boron the full name is Octoborate disodico tetrahydrate; the concentration is 10 per cent
in water.
However, both will diffuse out of bamboo when moist.
Method: open tank method, or modified Boucherie until moisture of 10 per cent of the
volume of the bamboo has left the lower end.
Diesel oil is not toxic, but beetles do not like the smell. They wait until the smell has
disappeared or until they are really hungry.
Three methods of treating the bamboo with these preservatives are as follows.
Put the solution into the trough, using a plastic bucket. Before putting the bamboo into the
trough, cut it to the required length, splitting it if required, in order not to treat bamboo which
will not be used. All bamboo should be covered with preservative. Put big stones on the
bamboo, enough to keep the bamboo down (Figure 1A).
Open tank method
An open tank is a trough of about 4m long. This can be made by cutting two 200-litre drums
in half vertically and welding them together like a canoe. Cut the drums with a cold chisel
and a hammer; flatten the shape edges with a hammer. After welding, paint the inside with
bitumen, tar, or anything like that to protect the drums from corrosion.
Put the solution into the trough, using a plastic bucket. Before putting the bamboo into the
trough, cut it to the required length, splitting it if required, in order not to treat bamboo which
will not be used. All bamboo should be covered with preservative. Put big stones on the
bamboo, enough to keep the bamboo down (Figure 1A).
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