Bamboo plants grow rapidly and reach maturity after only six years. Most come from a species of bamboo plant known as "Moso" that grows in China and other Asian countries. When they are harvested, the stalks are cut into logs, which are then sliced into thin strips and cut into uniform widths. These raw bamboo pieces are what will eventually become bamboo flooring, which is becoming a popular, economical and ecologically sound choice for hardwood flooring.
The bamboo strips are steamed under pressure to kill off any sugars or insects in the material. This carbonization process also darkens the wood somewhat and reduces its hardness. The darker the bamboo, the more it has been steamed and the softer it usually is. After the bamboo strips have been graded for quality, they are dried in a kiln to ensure that all the pieces have the same moisture content. In some Asian countries, bamboo flooring that is less processed is more common. Pieces of bamboo are simply cut to uniform lengths and nailed to wooden beams or other bamboo stems.
The dried strips of bamboo are milled so that they are all of equal thickness. They are glued together, either face up for horizontal flooring or side-by-side for a more uniform look, known as vertical flooring. Heat and pressure of up to 1,200 tons per square inch bonds the glued pieces together in the hot bonding process. Some bamboo flooring is cut with tongue-and-groove joints that interlock for easy assembly, similar to other hardwood floors.
The resulting boards of glued bamboo strips are once again milled to ensure uniform thickness and to create the common tongue-and-groove system common to hardwood floor assembly. While hardwood floor boards are made up of one piece of wood, bamboo boards typically consist of 15 strips glued into one piece for horizontal flooring and 19 strips glued together for vertical flooring. The boards are packaged and ready for shipment to retailers. If the bamboo has been carbonized, it usually takes on an oak color. If it retains its natural color, the look is more similar to beech.
Unlike traditional hardwood flooring types, bamboo flooring has no governing body to determine quality and uniformity of manufacturing. Variations in hardness and quality of assembly are common. Lower-grade bamboo flooring uses more formaldehyde resins in the gluing process, especially those made in China. While bamboo has developed a reputation as an eco-friendly renewable resource, controversy still exists over the deforestation techniques used to harvest commercial bamboo crops.