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Quality Control
Bamboo
Flooring Production Process

The quality of strips are of the utmost importance...


The harvested bamboo stalk is hollow with a hard outer wall and a softer inner wall. At the primary processing plant, long rectangular strips are cut from the stalk then milled to remove the inner and outer skin and nodes. This milling process also shapes the strip into the rough rectangular shape and dimensions required by the finishing plant. The strips that pass a final visual quality control inspection will be used to construct bamboo flooring, paneling or related items. Quality bamboo strips are the major factor in assembling a premium bamboo product.

The quality of strips is of the utmost importance since bamboo flooring is an assembled product consisting of approximately 15 strips for the horizontal construction and about 19 strips for the vertical construction. This manufacturing process is one of the major differences when compared to solid wood flooring.

GreenWood’s bamboo strips are obtained from plants located in the bamboo forests of the Fujian and Zhejiang provinces in China. There, the bamboo log is split into the rough strips and then processed into semi-finished strips and dried to reduce the moisture content to 12%. In GreenWood’s production process, many of the strips required for production into carbonized products are immediately steamed under high pressure. This process, known as carbonization, changes the color throughout the strip from a blonde, yellow color to a brown, coffee color. Carbonization reduces the strip hardness approximately 20%. Strips not carbonized at this point must be boiled to kill pests and remove sugar. If the boiling process is not done in a timely manner, the strips will begin to rot. The boiling process reduces the strip’s hardness by 8%. Most mills will first boil the strip and then carbonize the strip, thereby reducing the hardness of the carbonized strip by over 26%. Our manufacturer’s process removes the boiling requirement and preserves the hardness that is lost by the other method.

At the finishing plant, strips are again inspected for quality and separated into class “A” or class “B” strips. Only class “A” strips are used for GreenWood's flooring. “B” quality strips are sold at a discount to less demanding manufacturers. A major reason for the lower prices offered by some manufacturers and/or importers is their use of “B” quality strips.

After boiling or carbonizing, the strips are milled to a uniform size then kiln dried for three days, reducing the moisture content of the strips to 8-10%. The strips are now milled to a final width and thickness in preparation for finished plank assembly.

The final phase of bamboo flooring production begins with the gluing process. Most Chinese glue is high in formaldehyde and low in strength retention. GreenWood requires our manufacturers to use a high quality, European (E-1) glue that exceeds most indoor air quality requirements for formaldehyde emission. Our bamboo, when tested in a climate chamber according to ENV 717-1, 1998, Part 1, Annex A3, emits only 0.0127 parts per million of formaldehyde.

During the production process, glued strips are assembled face up for horizontal flooring and side by side for the vertical construction. Hot pressing, where heat and pressure of up to 1,200 tons PSI binds the strips together and allows for complete dispersion of the glue, is the next process.

A major quality consideration is the molding operation where the side and end tongue and grooves are milled to exacting tolerances that provides a uniform straight edge. The multi-step, German molding machine performs all milling functions in one pass. The diamond-tipped cutting tools assure close tolerance over long production runs. The manufacturer guarantees tolerances as follows:
Length: +/- 1mm, Width: +/- 0.1 mm, Thickness: +/- 0.1 mm

GreenWood supplies both square edged unfinished flooring and Micro Beveled pre-finished flooring. Our manufacturer has two fully equipped finishing lines that apply 6 coats of Treffert’s High Performance Coating (HPC). This finish consists of micro or nano particle modified acrylate urethane resins that combine extreme hardness with high mechanical resistance to scratch, impact and abrasion.

The boards are finely sanded during the finishing process with a high precision sanding machine. The sanding eliminates air pockets and pinholes from the final product and also guarantees the high adhesiveness of the urethane. Treffert, an internationally known European finish manufacturer, guarantees the finish for 15 years in a residential setting and 5 years for commercial use. These planks can be easily re-finished as the anti-abrasion particles are only added in the 2nd step of the finishing process.

 

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Sliced Bamboo Log

Carbonizing Strips

Final Milling of Strips

Inspecting Rough Strips

Assembling Strips

Glue Machine

Press Machine

Molding Machine

Finish Line