Bamboo is technically a giant, woody grass defined by its rapid growth and hollow, segmented stalk, known as a culm. This botanical classification dictates how the material reacts to moisture, particularly submersion. Whether you can submerge bamboo depends entirely on the duration of exposure and the preparation of the culm. A separate plant often confused with true bamboo is “Lucky Bamboo” (Dracaena sanderiana), which is actually a species of Dracaena commonly grown hydroponically in water. True bamboo is a structural material, and its integrity is highly susceptible to sustained water exposure.
Short-Term Soaking for Flexibility
The intentional submersion of cut bamboo culms in water has been practiced for centuries as a treatment process. This short-term soaking, often called leaching or water curing, removes starches and sugars from the plant’s internal structure. Freshly cut culms are typically submerged in tanks or running water for two to four weeks. This leaching process makes the bamboo less attractive to powder-post beetles and other pests that feed on the high starch content, increasing the culm’s natural durability. The absorbed moisture also temporarily increases the material’s flexibility, making it more pliable for bending and shaping in traditional crafting.
The Biology of Long-Term Water Damage
Sustained submersion lasting months or years is destructive to the structural composition of the bamboo culm. The plant cell walls are made of three primary structural polymers: cellulose, hemicellulose, and lignin. Fungal organisms are the most significant agents of deterioration in persistently wet environments. These fungi thrive in conditions of high moisture and begin to break down the bamboo’s structural components. The constant presence of water saturates the cell fibers, creating an ideal environment for mold fungi to colonize and cause rot. Fungal enzymes actively degrade the cell wall polymers. The breakdown of lignin, which provides rigidity and water resistance, further compromises the structural integrity of the culm, leading to softening, discoloration, and eventual collapse.
Preservation Methods for Water Use
To use bamboo in wet or submerged environments for extended periods, specific preservation treatments are necessary to counteract water and fungal attack. The most common chemical treatment involves soaking the culms in a solution of borates, typically a mixture of boric acid and borax. This process works by diffusing the chemicals into the cellular structure, making internal starches unpalatable to insects and inhibiting fungal growth. Borate solutions can be applied using a cold immersion tank method or a vertical soak diffusion method. Since borate salts are water-soluble, prolonged exposure to water will eventually cause the chemicals to leach out. For applications like decking or water features, a water-repelling physical barrier is applied after chemical treatment and drying, such as oil-based sealants, varnishes, or traditional charring.