When a bamboo colm, or stalk, reaches the height of 35 to 40 feet, it is harvested and inspected for imperfections and presence of pests. It is then cut into slats. The slats are treated with a borate solution to kill any pests and kiln-dried to a moisture content of between 6 and 9 percent.
After drying, the slats are planed, inspected and graded for use as surface or substrate material. The dried slats are then glued edge to edge to form a single-ply panel. Two or more sheets of laminate are then joined with glue in a hydraulic press.
Bamboo plywood is available in amber and natural color. The natural color, as its name implies, is the color of the bamboo at harvest. A heating process after drying that caramelizes the sugars in the bamboo produces an amber color. These darkened sugars pigment the material evenly throughout the entire strip, not just the surface.
There are more than 11,000 varieties of bamboo. These vary widely in size and utility and are native to many parts of the world. While most commonly found in Asia and South America, there is even one species native to the United States.
Most commercially available bamboo plywood is harvested from the "Moso" species of bamboo grass in China. This type of bamboo has a chute that reaches a harvestable height of 35 to 40 feet in about four years. Bamboo has an extensive root system. So, after harvesting, it grows back without replanting.
In its native form, bamboo has been used as a building material since the beginning of recorded history. Its high-tensile strength and light weight have proven useful in building everything from eating utensils to temples.
Recently, bamboo in plywood form has become popular in the United States. Most consumers have seen it in their local home-improvement centers as flooring. Some manufacturers have seen its potential for use in building furniture and cabinets.
Because of limited production facilities in China, the price of standard 4-by-8-foot ¾-inch sheets is in excess of $150 per sheet. This compares to a similar sheet of mahogany plywood for around $130 or the same size of maple plywood for about $70.
Woodworking Properties of Bamboo Plywood
Because of its hardness, bamboo tends to be brittle. Sharp, thin-bladed saws should be used for cuts. Pre-scoring the cuts will help as well.
Using screws or nails within an inch of the edge can cause splitting. Pilot holes are advisable for this type of attachment.
When using glue or a dowel-and-glue combination, the adhesive should be first tested on a piece of scrap. Bamboo is not very porous, so glue will tend to bond only to a thin surface layer on each piece.