What makes bamboo a green product is that it’s a grass and not a hardwood. It can be harvested every 4-6 yrs, depending up on the variety and how much fertilizing is done. Most all of the bamboo building products on the market come from China, some is coming out of Thailand and Vietnam, although these are not made from the hardest varieties of bamboo. To utilize the bamboo as a building product the 4-6 inch bamboo stalks are harvested and diced up into cubes, and cut into strips and however long they need to be. These strips are then processed by boiling and bug proofing and then laid up into boards, flooring and plywood.
The types of bamboo that you will see on the market are, vertical, horizontal (sometimes called flat), and oriented strand. Vertical bamboo looks like VG fir or pine, all of the strips are laid up on their sides in a vertical fashion, the nodes (growth rings), tend to show up as little eyes similar to the spots in birds eye maple. Horizontal has all the strips lying flat so that you see the nodes and has a more striking bamboo appearance. Oriented Strand is the newest product on the market. It utilizes all the scraps from the other processes, the surface has an interwoven appearance and it’s hard to tell that it’s not wood. OS bamboo is considered the hardest of the 3, due to the fact that it’s mostly glue and resin, which might be getting away from the “green” idea, at this point we don’t carry any OS products.
The colors that you will find in the market place are natural and carbonized (sometimes called caramelized). Natural is a blondish, honey color, from almost white to gold. Carbonized is the harder one to nail down as the color comes from heating it. Most carbonized bamboo will be a medium brown. The darker browns are usually a custom color from a specific manufacturer. We stay with one manufacturer so that the color from container to container will match. All of our products are available in the 4 standard types of bamboo:
Felt-backed veneer, 1/8” plywood backed veneer, the veneer is .6mm thick, and can be glued up like any standard wood veneer.
Dimensional boards are glued up with all of the layers running parallel to each other, ¾” horizontal will consist of 4 layers and the vertical will be a single layer all standing on edge. The 4/4 plank will have 5-6 layers of horizontal and 2 layers of vertical material. The sheet goods come in cross-laminated and plywood core.
Cross-laminated plywood has an outer layer that is 3-4mm thick on both sides and a ½” core that runs perpendicular to the outside. The interior core consists of vertical material so depending upon application it finishes well and has a nice appearance. Plywood core panels have the same 3-4mm outer layers with a plywood core, a money saving product for areas where the interior won’t be seen and won’t matter. The ½” sheets have the 3-4mm outer veneers with a 1/4'’ cross-laminated core.
When craftsmen first start using bamboo there might be some confusion as to whether there is an A and B side to a sheet or board. The A-side of the sheet will be sanded at 150grit and the other side will be at 100grit and you can usually feel the difference with your bare hand. The other way to tell is that the A-side will have more of an even color. Horizontal sheet goods, horizontal 1x8s (stair risers) and both types of 4/4 material (stair treads) will exhibit this difference. The difference can be striking, as some of the strips can be 2-3 shades lighter or darker.
Working with bamboo
Whatever you can do with a hardwood, you can do with bamboo. A comparison would be similar to working with Cherry. It won’t split like wood, as the grain is more linear, but you can chip off pieces if you get too big of a bite with a router. It’s very hard so it will dull blades and bits quicker. Due to the tightness of the grain we suggest pre-drilling screw holes before running in screws for hinges and such, call it insurance. When planning material, you may experience some chip out at the nodes if you try to take off too much at one time, so with a little caution there shouldn’t be any major surprises.
Standard finishing practices work well with bamboo, the one thing to advise against is using a straight polyurethane finish. Straight polys have been known to loose their grip on bamboo when subjected to impacts or even foot falls. Water borne polys over a sanding sealer work well, lacquers and oil based polys like Seal-a-Cell work well. The most successful stains we have found, when changing colors, are tung oil stains; they provide a good even color and penetration. Bamboo will stain different the wood so better to be safe than sorry, always try any finish you buy on a scrap piece first.
Bamboo doesn’t absorb moisture as quickly as wood, but it will and should be protected accordingly. If it’s humid and you leave sheets of bamboo out in an unheated warehouse with nothing over the top of the pallet the top sheet may curl. If this occurs take that piece inside where it’s dry, flip it over, put some weight on it or quit often when it’s cut up it will relax and lay down flat. So as a precaution it’s a good idea to put a piece of plastic over the pallet or at least another sheet of plywood over the top to protect your investment. Dimensional boards should be stored flat and protected as with any other material, items in their original boxes are inside of plastic bags.