To increase the durability of bamboo and to protect it from insects and fungal attacks, it is necessary to carry out reliable preservation of every bamboo pole. Bambooroo treat bamboo with naturally occurring salts of boron (Sodium Borate) which is a safe and environmentally friendly preservation chemical.
To 'load' the bamboo culm with sufficient levels of these salts for wood preservation we, "Horizontally Emerse" the bamboo culms in a 5 % solution which is a fast and reliable method to ensure our projects use the best material possible.
We start by individually hand selecting mature bamboo culms to harvest. The reason being that a 3 to 5 year old bamboo culm has sufficiently hardened (lignified) maximizing the physical properties of the bamboo.
These mature poles also shrink and crack less when dry and have a lower starch and sugar content that decreases the attractiveness for insects and fungi.
The thin bamboo tops not suitable for structural use are are immediately processed into flattened bamboo matts for cladded formwork and bamboo shingle roofs.
To prepare the poles for the treatment process we first clean the poles with a pressure washer. Next we longitudinally penetrate the diaphragms of the bamboo culms we attach a large drill to a long steel rebar and drill each node throughout the length of the bamboo.
This allows the preservation solution to fill up inside the hollow bamboo and allowing the borax solution to diffuse via osmosis into the soft interior wall.
Borax or sodium borate is a soft, colorless, powdery mineral that is dissolved in water and used as a the primary wood preservative at Bambooroo. We have bamboo pools up to 12.5 m to treat 12m long culms in the borax for 5-6 days.
The horizontal emersion technique works with the anatomy of the bamboo culm and allows the preservative to penetrate deep into the bamboo wall and load the entire culm with sufficient salt levels to deter any fungal or insect attack.
Next, the bamboo poles are left to bask in the sun for 1 week depending on the amount of sunlight here in Chiang Mai. The poles are sometimes rotated twice per day to avoid cracking in the hot summer sun. The sun bleaches the Chlorophyll in the bamboo to a golden yellow color that is more desirable as a construction material.
Once Bamboo poles are bleached, they are stored in a dry, dark place to undergo hot air injection using " el pulpo" (by Joerg Stamm) for fast efficient drying of bamboo poles, that rapidly decrease the humidity 2-3% per day.
Now that the poles are dried to 12-18% humidity, the poles are sorted and cut to length and colour coded as per diameter. The best poles are again separated according to the high export standards or selected for a Bambooroo construction project. The lesser quality poles are sold locally.
Poles that have cracked during the drying process are separated to undergo secondary processing or parallel splitting. We can create uniform splits at variety of width from 5 to 70mm bamboo splits from which we can make pin-boo boards, laminated panels, furniture, cladding etc. The thick base sections are used to make large diameter bamboo dowels for construction use.