The Nature of Rubber Wood

Rubber wood is a member of popular timbers utilized for industrial purposes. It is produced from Hevea brasiliensis aka the rubber tree- a type of tropical tree from which latex (the liquid which is used to make rubber) is obtained. 

This plant species was indigenous to Brazil then brought to Asia during the British Colonialism. And now rubber trees are widely planted in 20 countries around the world for the production of latex, especially in many parts of Africa, and South America, and Asia. 

At the age of 25 to 30 years after planting, Rubber trees start declining its production of natural latex. The mature rubber tree is about 30 meter tall with an average branch-free bole of 3 meter.

The Weaknesses of Rubber Wood

The latex production declining makes the wood uneconomic. The wood are then chopped down and changed for the new ones.

Previously, the chopped wood were just burnt or purposed as a cheap source for industrial brick burning, tobacco curing, or for fuelling of locomotive engines. It happened because rubber wood had some weaknesses.

The rubber wood, especially when it is newly harvested is easily attacked by wood boring insects and staining fungi such as blue stain and mold. It also easily rots in humid climate.

The Strengths of Rubber Wood

  • For many years, researches have been conducted to overcome these defects in order to generate a new income source for plantation holders and to supply inexpensive hardwood to the industry. 
  • Began in 1980’s, rubber wood emerged as an alternative source of tim­ber for the wood manufacture particularly sawn timber, furniture and wood based panel (Gong and Sim, 1994). 
  • Rubber wood then became a popular hardwood for making indoor building and furniture components. 
  • It is because rubber wood has some strengths. Firstly, the wood is suitable for a wide range of usages because it has favorable woodworking and timber properties. 
  • Due to its homogenous struc­ture, dimensional stability and uniform textures, it can be easily custom-built depending on consumer demand. 
  • It can be machined and routed to high quality since it has little shrinkage.  The timber can be sawed, planed to a flat surface, then be steam-bent or resemble to any other timber without difficulty. 
  • In addition, the wood is able to split in nailing but air dries quickly, that makes it easily be controlled in the kiln drying process. 
  • Another reason is rubber wood also has an attractive physical characteristic. The color of wood varies from white to light cream. 
  • However, the color changes to light straw or light brown, due to weathering. 
  • Lastly, rubber wood also has relatively cheap raw material price since the abun­dance of these tropical logs available after the completing their latex production. 
  • It makes the wood highly competitive in comparison with other timber. Even the price of treated rubber wood is still 30-40 per cent lower than other competing woods from non-plantation origin.

Characteristics of Rubber Wood

  • The characteristics of rubber wood are similar with the other maple family plants.  
  • The average diameter of old tree is 25-30 cm with a clear bole of up to 10 meter. Rubber wood has medium-sized fibers with about 1.5 mm long and 0.022 mm width. 
  • The cell wall is about 0.0028 mm thick. The wood is light because of the thick straight grain. 
  • This varies from straight to shallow interlocking. The texture of wood is homogeneous, and the sapwood is not easily distinguishable from the heartwood. 
  • It is lustrous coarse- textured wood. The wood is rather soft and has sour smell. It has a pleasant appearance in color which is white to pale cream with a pinkish tinge sometimes. 
  • Due to weathering, the color can change to light straw or light brown.

The Best Uses of Rubber Wood

  • Rubber wood has become the most stable construction materials available for furniture manufacturing, whether for wooden furniture or indoor structure components. 
  • It is mainly wooden furniture such as living room set, bedroom sets, dining sets, children furniture, casts, and chairs. 
  • The wood also purposed in producing moldings and a wide range of items like utility household items, kitchen sets such as trays, knife blocks, bowls, magazine racks, and bookshelves. 
  • This wood also makes attractive paneling, edging, skirting board, beading, strip flooring, parquet. 
  • For the small pieces, they are usually laminated with glue and applied for railings, steps, stairs balusters, door, and window decorations. 
  • While the smallest size or chips logs are used for particleboards, plywood, cement boards, medium density fiber board, and furniture components such as ceiling panels, chair seats, table tops, and back rests.

Rubber Wood as Eco- Friendly Lumber

  • After the economic life, rubber trees have to be chopped down for replanting or converting the land for other uses. 
  • This is the only time when rubber wood is ready to be supplied, unlike other woods which cut down for the sole purpose of producing furniture. 
  • Furthermore, during its lifetime, rubber wood contributes much oxygen for the environment until it completes the latex production cycle then dies. 
  • Then when it is processed into lumber, the residue and sawdust are also can be recycled. 
  • They are used as fuel for equipment for heating. The sawdust also can be used for mushrooms cultivation. 
  • These facts considered as reasons for labeling rubber wood as an ecologically friendly lumber in furniture industry.

Rubber Wood Processing

  • In processing the rubber wood sawn timber, there are some sequence activities to prepare the wood into a final product. 
  • The wood processing is usually categorized into primary and secondary. The primary processing begins with sawmilling conversion and veneering activities directly on stem logs. 
  • Then it is continued into the next step called secondary processing. In this stage, the sawn timber is further subjected to downstream processing for the production of rough sawn kiln dried wood by applying preservative treatment and drying. 
  • Finally the lumber is cut into finished sizes for furniture components and other value-added products.

Essential Techniques in Processing Rubber Wood

  • After freshly cut, the green timber has high moisture content and is susceptible to sap stain fungi infestation and defects like end splitting and twisting, especially in the tropical humid climatic conditions. 
  • Therefore, some essential techniques are suggested to be done during sawing process to prevent these defects. 
  • The main thing is not sawing through the trunk and allowing unleavened at the end. Then fasten the sawn timber with a piece of wire or drive a nail at the end of log. Only unfasten it if it will be used. 
  • Immediately soak the sawn timber in water for 1-2 days since after sawing new surface are exposed to fungal, kill mold, staining organisms and insects attack. 
  • Therefore the freshly sawn pieces must be dipped into the preservative solution. After that, the treated timber boards need to be dried. 
  • Rubber wood commonly dries easily but also easy to bows, twists, and springs. Therefore the right way of drying is the key, whether by air seasoning or by kiln seasoning. 
  • For air seasoning, the length of air-drying depends upon prevailing weather conditions. A small log which larger more than 6 inch diameter will season in 4- 6 months during dry period. 
  • While for wood with more than 30 cm diameter, it should be lumbering before seasoning. This seasoning process can make the timber straight without twisting and end splitting. 
  • Some nonchemical treatments also can be applied for the drying process. They are burning the wood surface slightly without producing flames, and only using the wood in open areas.  
  • At the end, the lumber should be print coat for decreased evaporate moisture from wood.

The Potential Outlook for Rubber Wood

  • The fact that rubber wood has sustainable availability with lower cost but high in quality has contributed towards the potential outlook for rubber wood. 
  • This wood ranks the first position among other tropical hardwood in terms of available volume since rubber wood is an agricultural by-product. 
  • It is important to be considered that the farming management has to be integrated between the production of latex and the final result of the rubber wood. 
  • Therefore an intensive farming is needed to balance the quality of latex and rubber wood as a potential timber. 
  • The improvement forest management and cutting techniques are the keys to obtain the best quality of rubber trees while they still produce latex. 
  • After the latex production is over, preservative treatment should be applied in processing the rubber wood into timber. 
  • The potential value of the raw materials would be even higher if the lumber is further processed and exported as finished products like furniture, builders, woodworks and other high value added products. 
  • The success of rubber wood products in world market is due to its excellent physical and dura­bility which is supported by good technological properties. 
  • The development of chemical treatment processes allowed the wood gained popularity and acceptance as sawn lumber and as furniture and other high value products. 
  • It can be assumed that rubber wood will still have a big market both in the local and export in the future.