Bamboo: Maintaining The Grass That Acts Like Wood
April 12, 2011
Somewhere in the early to mid-1990s, bamboo flooring arrived in the United States and since that time has made a considerable impact in the flooring market. Although bamboo was initially met with a certain amount of skepticism (and there’s still some out there), it is now a force to be reckoned with.
The floor maintenance technician will be hard pressed not to encounter this flooring material sometime in their career and, as Louis Pasteur once said, “Chance favors the prepared mind.”
Bamboo, like any other flooring material, has properties and characteristics unique to its classification. These properties and characteristics dictate how it will look and perform in different environments. The construction and manufacturing processes also contribute to these classification traits, and are helpful for the floor-maintenance technician learning to understand how maintenance impacts them.
When you look at some species of bamboo, you would assume that it is a tree, but bamboo is really a grass. The stem or trunk of the bamboo plant is called the culm. It looks like a series of hollow cylindrical chambers that are jointed (nodes) and tapered to the top. Color ranges from green and gold to brown and, in some cases, striped.
There are many different species of bamboo, but the most common species used for flooring material is Moso (phyllostachys edulis) bamboo. Moso can grow as tall as 60 feet with a diameter of 5 to 7 inches, and can be harvested every 3 to 8 years. Because of its rapid growth it is considered to be an “eco-friendly” flooring material.
In order for bamboo to be used as a flooring material, it must possess the properties of durability which equate into hardness. The hardness of bamboo is measured using the Janka hardness scale, which produces a rating value by measuring the pounds of force required to embed an 11.28 mm (0.444 in) steel ball into the bamboo to half the ball’s diameter.
The Janka hardness rating ranges from as low as 100 (balsa) to as high as 4500 (lignum vitae). Natural bamboo ranges between the values of 1380 – 1410 which is somewhere between the hardness of white oak and hard/sugar maple. Carbonized bamboo is somewhat softer, with a rating range between 1010 and 1120 which is harder than heart pine, but softer than black walnut.
Which begs the question, why such a wide range of hardness?
Many factors play into the hardness of bamboo, which is why it is all over the chart. When it is harvested in its growth cycle and how it is manufactured are key components to the hardness factor. Additionally, there are very few laws that govern the quality control of products coming from foreign nations, making consistency difficult.
The manufacturing process begins with the culm or stalk of the bamboo being sliced, cut into strips and steamed under pressure to sanitize the product. Carbonized bamboo undergoes the process for a longer period of time which produces the darker colors associated with carbonized bamboo, however the additional steaming also reduces the hardness rating.
The strips are kiln dried and glued together using a combination of heat and pressure in the bonding process. Horizontal bamboo flooring is achieved by gluing the strips face up which allows the nodes to be visible and vertical flooring is achieved by gluing the strips side by side which gives the floor more of a striped appearance. Both of these processes are for solid bamboo of which the bamboo may be natural or carbonized.
Other types of bamboo include engineered and strand woven. Engineered bamboo is similar to solid bamboo; however, the cross-layered underlayers can be made of less expensive softwoods or lower grade bamboo and contain 3 to 7 layers. Strand woven bamboo is made by gluing shredded fibers from the culm together under extreme heat and pressure. The result is a very durable product and can be either natural or carbonized.
The boards of glued strips are then milled to make the tongue and groove slats used for installing the flooring material. Finally, the boards are stained and finished. The finishes used for bamboo flooring are generally polyurethane or urethane coatings that, in some cases, contain aluminum oxide, which gives the flooring a very durable finish.
All bamboo flooring is not the same and some is less durable than others. Some bamboo flooring can be indented with your thumbnail or easily scratched with a coin.
The primary concerns when maintaining bamboo flooring are indenting, scratching and moisture. Most wood floors have the same issues. There is very little the floor maintenance technician can do about indenting and scratching. High-heel strikes and objects being slid across the floor will cause these conditions and once they have occurred, they are there. Owners of bamboo flooring may wish to consider area rugs or walk off mats to help combat some of these conditions. This is especially true of walk off mats in entrance areas that are exposed to the outside elements.
Maintenance for bamboo, like most wood floors, is relatively easy: dust mop, sweep or vacuum regularly and damp mop with neutral cleaner solution when needed. For the most part this will keep the light to moderate soil in check. With heavy soil you may have to do a wet mop and rinse. When this service procedure is performed, it is important to remove as much solution from the floor as possible.
Wet vacuuming followed by a damp mop will remove most of the moisture, but understand that water seeks the path of least resistance and migrates to the lowest point. This means that moisture will seep between the joints where the slats are joined and continue downward to the subfloor.
Although the top of the bamboo flooring is sealed with durable polyurethane or urethane coating, what’s underneath is not. Excessive moisture may cause discoloring, warping or cupping.
Periodic maintenance may incorporate a screening with a fine grit screen followed by a single coat of urethane or polyurethane. Restorative maintenance may require moderate to coarse grit to start, finer grits to finish, followed by two coats of urethane or polyurethane. Both of these service procedures should be performed by trained professional technicians.
Bamboo flooring may be relatively new to the industry, but it sure looks like it is going to be here for a while. Understanding what it is, how it is manufactured and the properties and characteristics will help the floor maintenance technician provide better service for his customers.