What is the manufacturing process of bamboo?

How is Bamboo Textile Fibre made?

Read more

Bamboo forests in China have been cultivated extensively for hundreds, if not thousands, of years. Every spring and summer, new poles (culms) emerge from underground shoots. A young shoot of the larger timber bamboo varieties weighs between 2-4 kg and is less than 30cm high. At this stage, it is soft and can be cut with a knife, and when prepared properly, it is also edible. If allowed to grow, this shoot reaches a height of around 20 metres within an astonishing 3 months, depending on the variety. Once mature, bamboo timber is incredibly resilient and strong, boasting tensile strength comparable to mild steel.

Bamboo textile fibre is derived from bamboo timber that has matured for at least 4 years in the forest. Even in remote areas of China, bamboo forests are highly valued and meticulously managed. When new shoots reach their full height during summer, they are marked with a year code to ensure they are harvested at the optimal maturity. Upon harvesting, the bamboo is taken to mills, crushed, and submersed in a strong sodium hydroxide solution to dissolve the bamboo cellulose. The addition of carbon disulfide allows the mixture to regenerate fibres, which are then drawn off, washed, bleached, and dried to a bright white colour. The resulting fluff is long in staple and visibly finer than other fibres. These are then spun into yarn, similar to other textile fibres. The longer staples and higher tensile strength result in a tough, soft yarn resistant to wearing and fraying, providing bamboo fabrics with excellent durability. The fibre's hollowness contributes to its high absorbency, but it also means it takes longer to dry. Additionally, the fibre's hollowness makes it more receptive to dyes and pigments, enhancing its colourfastness.

The main chemicals used in this process are sodium hydroxide and carbon disulfide.

Carbon disulfide was only identified as a nerve poison after workers in Italy were exposed to high concentrations during the 1930s and 1940s. Today, with adequate ventilation, it poses no significant problem and breaks down when in contact with natural elements. Neither carbon nor sulfur, the components of carbon disulfide, are poisonous.

Sodium hydroxide, also known as caustic soda, is strongly alkaline and reacts with many substances. However, it is not toxic and is used extensively in cooking. For example, in high concentrations, it gives traditional pretzels their distinctive flavour.

BT "Kitchen Chemistry" Video Demonstration

We have created a video to provide a clear understanding of how bamboo fibre or bamboo rayon is produced.

While the demonstration does not depict the exact commercial process, as that takes significantly more time, the underlying principles are the same.

1. Isolating the cellulose from bamboo
2. Dissolving the cellulose
3. Regenerating the cellulose to form rayon (also known as viscose).

We call the video "Kitchen Chemistry" because the substances involved are almost as benign as those used in everyday kitchens and households.

What is the Manufacturing Process of Bamboo Timber?

One of my friends who works in wood furniture once mentioned that buying one piece of bamboo furniture is equivalent to saving one tree. Bamboo furniture not only addresses the economic income issues of local bamboo farmers but also mitigates the shortage of solid wood, contributing to the protection of forest resources. Additionally, bamboo timber is low-carbon and environmentally friendly. As a result, bamboo furniture such as summer sleeping mats, tables, plates, shoe racks, trays, and pen containers has become increasingly prevalent in our lives.

But do you know how a piece of bamboo is transformed into furniture? Today, we will explore the process.

1. Raw Material Quality Check

Bamboo used should be older than 4 years, as bamboo younger than this age has insufficient lignification, leading to unstable strength and greater shrinkage and expansion rates. Typically, bamboo older than 5 years is chosen.

Generally, bamboo with a diameter at breast height of more than 10cm and a wall thickness of more than 7mm is selected.

2. Cutting Off

The bamboo is cut to length and split into strips for further processing.

3. Bamboo Strip Preparation

The original bamboo is punched into regular bamboo strips.

4. Double-Sided Planning

The initial bamboo strips undergo fine shaving on all sides to remove residual bamboo green, yellow, and knife marks left by rough planning. This preparation ensures firm adhesion without cracks or delamination.

After fine planning, bamboo strips are sorted, and non-conforming or highly discolored strips are removed from the production line.

5. Steaming or Carbonization

Bamboo strips undergo cooking (natural colour) or high-temperature carbonization (brown) to remove proteins, sugars, and other extractives. Insect repellent and preservative are added to prevent insect and fungal growth.

6. Drying

Post-steaming, the bamboo's moisture content exceeds 80%. To ensure size and shape stability, the bamboo raw materials must be fully dried before gluing. Moisture content is controlled according to local climate and usage, typically between 5-9%.

7. Fine Planning

Bamboo strips are finely planed to meet required specifications.

8. Sorting Bamboo Strips

Bamboo strips are sorted into different grades.

9. Gluing and Hot Pressing

High-quality, eco-friendly adhesive is evenly spread on bamboo strips, which are then assembled into blanks and hot-pressed.

10. Fixed Length Cutting

Blanks are cut to the required length.

11. Plate Separation

The blanks are separated into plates.

12. Deburring

Rough edges are removed from the plates.

13. Sanding

The blank plates are sanded to achieve a smooth surface and a uniform thickness.

14. Painting

High-quality, environmentally-friendly paint is applied to maintain a healthy home environment while ensuring aesthetic, waterproof, and pest-resistant properties. Sanding between each paint layer ensures smooth, bubble-free surfaces.

15. Finished Product Inspection

Finished products undergo inspections for adhesion, surface quality, abrasion resistance, and glossiness.

Watch How Bamboo Furniture is Made

eooe, bamboo products processing equipment manufacturing