Since bamboo's initial introduction to the U.S. flooring market in the early 1990s, it has continued to evolve into different flooring formats, which has served to increase the product's use and demand, especially in today's eco-conscious flooring market.
But first a quick little history on bamboo to help you and your customers understand it better. Bamboo has a long and interesting history dating back more than 5,000 years. The ancient Chinese used this versatile grass—that's right, though it is commonly referred to as a hardwood, bamboo is technically a grass—for many projects, including arrow making, construction, weaving, books, and paper.
There are literally hundreds of species of bamboo, and similar to trees, each one has its own characteristics. Moso bamboo is the species most commonly used for flooring because of its durability. Interestingly, bamboo can be harvested without the need to replant because the root system is left intact when it is harvested.
The initial introduction of bamboo for use in flooring was in the form of round bamboo stalks cut into endless little strips approximately ¼-inch thick by 5/8-inch wide. These strips were naturally a straw color but could also be steamed to yield a caramel color.
These bamboo strips were then laminated together into either of two formats:
• A vertical grain format, which yielded a very linear look from the numerous face-glued ¼-inch thick strips, which were 5/8-inch wide and hence yielded flooring 5/8-inch thick.
• A horizontal grain format, which came from edge-gluing the ¼-inch thick by 5/8-inch wide strips together to make up the flooring width and then laminating three of these ¼-inch thick layers of these edge-glued strips together face to face to make up the flooring's 5/8-inch overall thickness. This horizontal grain bamboo flooring fully revealed the cross-width "knuckles" that are unique to bamboo.
This bamboo flooring was offered in its natural cream color or the carbonized caramel color with a clear finish on top. The flooring could also be stained to your color of choice.
This first-generation of bamboo flooring was launched with great fanfare into the U.S. market and was promptly marketed as harder than oak—and unfortunately oversold on this point, I might add—when in fact much of it was softer than oak and closer in density to walnut, and hence was easier to heel dent.
Today we refer to this original bamboo flooring format as Traditional Bamboo.
Stage Two
The second coming in bamboo flooring was with the introduction of the strand woven format somewhere between 2002 and 2003.
In this format, the ¼-inch by 5/8-inch sawn strips of bamboo cut from the bamboo stalk were now partially shredded to open up and expose the stringy bamboo fiber. Then, phenolic resins were added prior to pressing the shredded bamboo under tremendous pressure, yielding a densified bamboo/resin composite product that effectively tripled the hardness of the product.
Once again, this product was offered with clear top coats in the natural straw color, the carbonized caramel shade, or a mix of both in the so-called tiger hue. And for additional colors, the strand woven bamboo flooring's surface was stained to the consumer's color choice prior to top coating it.
This new bamboo flooring category took quite a while to perfect in manufacturing, with early generations being prone to cupping, fiber raising and checking post-installation.
Additionally, it took quite some time for installers and mastic manufacturers to catch up to the proper methodologies to use when installing this product. Especially since strand woven bamboo, due to its resin content, does not "breathe" in the same manner as wood flooring and hence required a learning curve to install properly in various site conditions.
In the strand woven category, recent innovations now include the following:
• Dyeing the shredded bamboo fiber itself and then adding tints to the phenolic resins prior to pressing them together. We call this "fusing" the color into the product itself versus just adding a stain color on top of the flooring when seeking to increase the color options available.
• And now, the strand woven or "densified" category has been expanded beyond just bamboo to include various natural fiber sources such as wood, including poplar and eucalyptus, from post-industrial recycled veneer sources or mulberry wood recycled from silkworm farms, and coconut recycled from plantations.
Stage Three
The third coming in bamboo flooring is now unfurled bamboo, which was introduced between 2011 and 2012.
This format takes the round stalk of bamboo and runs a single slit up the length of the stalk. The round stalk is then carefully unfurled and flattened into a sheet whose width is that of the circumference of the round stalk—approximately 6- to 8-inches wide by the length of the stalk and by the thickness of the stalk's wall, which is approximately ¼-inch thick.
Now, for the first time ever, bamboo has a wide, single piece—6- to 8-inch—face, with the knuckle running across its full width. This sheet can be used as is as a wearlayer or three pieces may be laminated together in thickness prior to running it into flooring, yielding the standard ¾-inch wood flooring thickness found in the U.S.
Even more unique, unfurled bamboo allows you to leave the natural skin on—just as it comes from the bamboo grove—and use this skin as the flooring's natural finish without the need for top coating with man-made finishes. Or, you can partially remove the natural skin and tint/top coat with traditional UV finishes.
But unique to unfurled bamboo being finished with UV finishes is the one-piece face with the knuckles running fully across the face, given bamboo's unique cellular and fiber structure, whereby the outer skin is by far the hardest and most impact resistant part of the bamboo stalk. In fact, initial ball drop impact tests on the natural skinned, unfurled bamboo—which better replicate walking in high heels on the flooring than a lab Janka hardness test—amazingly show less denting than even on the densified strand woven format.
And this we believe is the result of both the hardness of the natural bamboo skin coupled with the stringy fibers from bamboo, which are largely concentrated in the bamboo stalk's wall just under the skin, acting much like steel rebar used for tensioning and reinforcing concrete for strength.
Or, you can simply think of skin and underlying fibers in unfurled bamboo's outer surface as a trampoline, whereby high-heel impact/ball-drop impact springs back as a result of the skin/fiber tension, producing little to no denting.
Given unfurled bamboo's newness, it will be interesting to see how it performs in the market and whether it can match the excitement that strand woven bamboo generated when it was first introduced over a decade ago.
William Jopling is CEO of TW Flooring Group and has an extensive background in developing and introducing new wood species into the North American Flooring Market and has been involved with bamboo from the early days of its introduction into flooring use.
