Preservation of bamboo and cane for non-structural purposes - Code of practice
2006 Edition

IS 1902 advises using preservatives such as coal tar creosote—a distillate fraction with a boiling point above 200°C—commonly mixed with fuel oil in a 3:7 ratio to minimize evaporation and leaching. Additionally, copper and zinc salts of naphthenic or abietic acids are recommended. Treatment involves vertically immersing green bamboo up to 1.8 meters in a water-based preservative solution, with the bottom 250 mm submerged and the top kept moist with a cotton cloth. After seven days, the bamboo is inverted to ensure even preservative diffusion, effectively protecting bamboo and cane in indoor and outdoor non-structural uses.

The diffusion method entails submerging the bottom 250 mm of green bamboo (up to 1.8 meters in length) vertically in a water-soluble preservative solution while keeping the top end moist with a wet cotton cloth. Preservative ions gradually penetrate the bamboo's vascular system, displacing the natural sap through diffusion. After seven days, the bamboo is turned upside down to promote uniform preservative distribution. Factors influencing diffusion include the moisture content, anatomical structure of the bamboo, preservative ion mobility, solution temperature, and immersion duration. This process is a straightforward, pressure-free technique relying on natural diffusion for internal preservation.

Green bamboo treatment leverages its natural sap vessels, allowing preservatives to enter via diffusion and methods like the modified Boucherie process. It involves immersing the bottom 250 mm in preservative solution, maintaining moisture at the top, and inverting the bamboo after treatment to ensure uniform penetration. Dry bamboo, however, poses a challenge due to impermeable membranes restricting preservative absorption and is typically treated using surface applications, dipping, soaking, or vacuum/pressure methods with less effective penetration. Consequently, green bamboo treatments usually result in superior preservative uptake and extended durability, whereas dry bamboo preservation offers limited protection.

To measure preservative absorption, samples are taken from treated bamboo or cane, typically weighing about 50 grams for cane and 100 grams for bamboo per 100 kilograms treated. Absorption is determined through chemical analysis of these samples, complemented by weighing before and after treatment when feasible. Visual penetration can also be assessed for certain preservatives using colorimetric tests. Absorption is calculated by dividing the weight increase after treatment by the sample's volume, with typical absorption values ranging from 4 to 8 kilograms per cubic meter depending on the preservative and treatment method.

Yes, IS 1902 specifies that waste from treated bamboo and cane contains toxic preservatives and must be handled carefully to avoid environmental contamination. Branches and offcuts retain these chemicals and do not decompose naturally. The recommended disposal procedures involve burning the waste openly to destroy toxic compounds, followed by burying the resultant ashes to prevent leaching. Alternatively, any environmentally safe method that securely contains the chemicals may be employed to ensure safety and environmental protection.