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Rubberwood - the success of an agricultural by-product

W. Killmann and L.T. Hong

Wulf Killmann is Director of the Forest
Products Division, FAO Forestry Department.
Hong Lay Thong is Director of the
Techno-Economics Division,
Forest Research Institute Malaysia (FRIM),
Kuala Lumpur, Malaysia.

The inexpensive wood from plantation rubber trees, felled when they no longer yield adequate latex, is finding a market in high-value end products traditionally associated with more valuable hardwoods such as teak.

The wood from rubber tree stems (Hevea brasiliensis Muell. Arg.) has become the raw material for a wide variety of end products of varying quality, substituting timber from the natural forests.

Rubberwood becomes available from agricultural plantations when replanting is carried out after 25 to 30 years because of declining latex yield.

Although rubberwood (sometimes called hevea wood) is a relatively inexpensive and mass-produced timber, it is now being used and marketed in many applications in which higher-value, less available hardwoods such as teak (Tectona grandis) have traditionally been used. These include furniture, flooring, wood panels and indoor building components. It is not durable enough, however, for use in some situations requiring the durability of teak, such as boat building, bulwarks, construction and transmission line poles.

The availability of rubberwood in large quantities is partly a result of the trees' undemanding site requirements, but mainly of the fact that rubberwood is only a by-product of a crop grown for latex production. An additional, vital factor for the availability of rubberwood is, at least in Malaysia, strong governmental support and incentives to ensure the continuing supply of latex through replanting of rubber plantations.

Most of the technical problems in processing and utilization of rubberwood have been overcome by the Southeast Asian countries over the past 20 years and the timber has been successfully marketed internationally. Rubberwood has thus become a Southeast Asian success story. It is even more important than teak as a plantation timber in Southeast Asia.

This article presents general information on rubberwood, its properties, processing, markets and products.

A rubberwood plantation near Seremban, Negri Sembilan, Malaysia



In pre-Columbian times latex from different plants in Central and South America was used for the production of balls and other rubber products. The invention of vulcanization by Charles Goodyear in 1839 laid the basis for the modern technical use of natural latex. During the second part of the nineteenth century, Hevea brasiliensis (Amerindian name heve) became the most important among the many latex-producing plants for production of natural rubber (Amerindian name cahuchu).

Hevea brasiliensis is indigenous to the Amazon basin. During the nineteenth century, Brazil was the main supplier of hevea latex, which was collected through tapping of trees in the natural forest. The wealth acquired in Manaus, Brazil, through the rubber boom and its impact on the development of the city around the beginning of the twentieth century have become legendary.

In 1876 Sir Henry Wickham of the United Kingdom smuggled hevea seedlings out of Brazil to the United Kingdom. Some surviving plantlets were then transferred to the new Singapore Botanical Garden. They became the planting stock for the first rubber plantations in the Malay State of Perak. They were also the parent planting stock for all rubber plantations in present-day Malaysia and other Southeast Asian countries developed at the turn of the twentieth century. Hevea has since been planted in a number of tropical countries as a plantation crop. The most important rubber producers today are in Southeast Asia; Brazil hardly has a role any longer (Table 1).

TABLE 1. Rubber plantation area of major producing countries worldwide ('000 ha)






1 564

1 878

2 269


1 620

1 610

1 420


1 269

1 420

1 555

Viet Nam




















Sri Lanka








Asia total

5 073

6 214

6 731













Côte d'Ivoire




West Africa total












Latin America total





5 314

6 650

7 183

Source: FAO (1999).

Tapping of rubber trees starts in the fifth to seventh year after planting and then continues for 25 to 30 years. It is done by incising the bark with a special knife and wounding the resin canals, usually without damaging the cambium.

After 30 years, a decline in latex production makes further tapping of the trees uneconomical. The trees are then removed and replaced with new seedlings. In the past, felled hevea trees were either burnt on the spot or used as fuel for locomotive engines, brick burning or latex curing.

A 30-year-old cultivated hevea tree is about 30 m tall with an average branch-free bole of 3 m. The diameter at breast height (DBH) may reach about 30 cm. The stem tends to taper. Young rubber trees have a smooth brown-green bark. The constantly tapped portions of the stem may develop with age into a latex-smeared cortex.


More than 80 percent of the 7.2 million hectares of plantations established worldwide for latex production in 1999 are in Southeast Asia; 70 percent of the total (or 5.2 million ha) are in Indonesia, Malaysia and Thailand (FAO, 1999). For decades, Malaysia had the largest area, followed by Indonesia and Thailand. With increasing wages in Malaysia and decreasing rubber prices, labour-intensive production of natural rubber in larger estates is slowly shifting to lower-wage countries in the region, while in Malaysia plantations are increasingly replanted with oil-palms (Elaeis guineensis) (Table 2). Indonesia is now the world's largest producer of natural rubber from Hevea brasiliensis.

TABLE 2. Area replanted with rubber trees in Malaysia (ha)



Other crops


% Hevea


31 500

7 700

39 200



33 000

8 400

41 400



31 100

10 400

41 500



26 100

12 800

38 900



22 900

14 000

36 900



21 600

13 000

34 600



11 300

13 000

24 300



9 100

11 000

20 100


Source: FDM Asia (1999).

In 1990 the total annual available volume of rubberwood in the area of the Association of Southeast-Asian Nations (ASEAN) was estimated to be about 17 million m3 (Ser, 1990). From 1982 to 1992 rubberwood production figures for Malaysia increased from 30 000 to 1 872 000 m3 (Malaysian Ministry of Primary Industries, 1993).

Raymond (1993) assessed that, based on a sawntimber recovery of 25 to 45 percent, only 5 percent of the rubber tree wood volume has been converted into wood product, the remainder being left behind in plantations or burnt. There are various other reasons for the difference between the statistically assessed available timber and the real outputs.

Available log volume for diameters above 15 cm ranges from 52 to 162 m3 per hectare (assessed for nine cultivars by Gan, Ho and Chew, 1985). The usable wood volume per hectare depends on numerous factors such as clone, site and management. Most of the planted area is owned by smallholders (with less than 20 ha). These plantings are geographically dispersed and accessibility is often poor.

Smallholders are said to provide logs of lower quality as they devote less attention to management and proper tapping practices (see below for the effect of improper tapping practices on the properties of the wood). A study undertaken in Johore, Malaysia, found that only 18 percent of rubberwood logs harvested in smallholder areas were suitable for sawntimber (H. Norini and A.U. Zana, unpublished, 1993).

Transport costs for logs are usually borne by the supplier. Because rubberwood log prices are low, particularly for low-quality logs, financial gains for smallholders from log sales have been negligible (Kollert and Zana, 1994). Therefore smallholders often prefer to burn the logs or let them rot in the plantation after felling. Thus, a major portion of industrially used rubberwood has come from large-scale plantations, where logs are of much better quality and felling and transport per log are less costly.

In the 1990s concerns regarding the future supply of rubberwood within Malaysia triggered a research pro-gramme on rubberwood breeding with the double objective of producing high latex yields and timber. The overall area planted with hevea is currently increasing, signalling an ensured future supply of the timber. Rubberwood now has a position no other single tropical hardwood species can match in terms of available volume.


Fresh, sawn rubberwood is white to creamy in colour, sometimes with a pinkish tinge, and has a fairly straight grain. It turns yellowish after seasoning. Heartwood and sapwood are not distinguishable. Pores are large and scattered and show radially and tangentially as brown lines.

Improper tapping practices cause an interruption in the normally homo-geneous creamy colour. If the tapper accidentally cuts through the cambium, deposits and fungi introduced by the knife cause a black stain along the growth rings, which is considered a defect in the timber. In addition, the traumatic reaction of the cambial tissue produces a callus.

The air-dry density ranges from 560 to 650 kg per cubic metre, depending on clone, age, site and plantation management. Fresh rubberwood has an initial moisture content of 60 to 80 percent (Killmann, 1992). The timber tends to develop seasoning defects such as cupping, twisting, bowing and checking, particularly in heartwood from the centre of the stem. A brown discoloration of the timber is sometimes observed after kiln seasoning.

Fresh rubberwood has a creamy homogeneous colour; heartwood and sapwood are not distinguishable


The timber has good overall qualities for woodworking and machining - for sawing, boring, turning, nailing and glueing. However, remaining latex can clog the sawteeth, and they have to be cleaned frequently. Tension wood can lead to fuzzy grain when machined. Rubberwood is easy to mould with feed speeds above 20 m per minute (Gloeckner, 1990; Rumboll, 1990). Fingerjointing is often applied to achieve larger dimensions. Rubberwood can be steam-bent with good results. When properly sanded it takes finishes well, and it can easily be stained to resemble walnut, cherry, oak or other woods, depending on consumer demand. In strength and mechanical properties it is comparable to traditional timbers used for furniture making and woodworking. Table 3 compares its physical and mechanical properties with those of teak.

TABLE 3. Physical and mechanical properties of rubberwood and teak


Rubberwood (at 15% moisture content)

Teak (at 12% moisture content)


460-650 kg/m3

480-850 kg/m3

Modulus of rupture (MOR)

66 N/mm2

86-170 N/mm2

Modulus of elasticity (MOE)

9 240 N/mm2

10 500-15 600 N/mm2

Compression parallel to grain

32 N/mm2

55 N/mm2

Compression perpendicular to grain

5 N/mm2

6.5 N/mm2


11 N/mm2

11 N/mm2

Hardness (Janka)

4 350 N

4 500 N

Source: Lee et al. (1982), rubberwood; Soerianegara and Lehmmens (1993), teak.

Fresh rubberwood contains 1 to 2.3 percent free sugars and 7.5 to 10.2 percent starch. Because of the relatively high content of free sugars and the absence of extractives, the wood is non-durable and is easily attacked by fungi and insects. The content of free carbohydrates has also created other problems, e.g. for the setting of cement in cement-bonded panels manufactured in Malaysia. This problem was resolved by open-air storage of the chips, which reduced the sugar and starch to 0.2 and 1 percent, respectively (Killmann, 1992).


Rubberwood has traditionally been used as a cheap source of fuelwood in most of the countries where rubber plantations are abundant. It is also used industrially for brick burning and tobacco curing. Because of its lack of durability the wood was not traditionally used as timber except in timber-scarce countries such as India and Sri Lanka, where it has been used for general utility purposes.

Some processing problems had to be overcome, as described above, before rubberwood could be widely marketed. Being naturally non-durable, rubber-wood is not economically usable without preservative treatment. Through
research and development efforts protective measures have been prescribed which are now routine for rubberwood processing.

Rubberwood's favourable woodworking and timber properties make it suitable for a wide scope of applications. Salleh (1984) reported 61 different products made from rubberwood. Its most important uses are in furniture and furniture parts, parquet, panelling, wood-based panels (particle board, cement- and gypsum-bonded panels, medium-density fibreboard) and kitchen and novelty items, and as sawntimber for general utility and fuel.

Rubberwood has a number of advantages over conventional timbers from the natural forest. Because it is a plantation by-product, it is available at relatively low cost. For example, the log price for rubberwood was found to constitute only 5 to 6 percent of the sawntimber price, compared with 50 to 60 percent for dark red meranti (Shorea spp.) (Kollert and Zana, 1994). Thus, in spite of its comparably low recovery rate, the costs for producing 1 m3 of rubberwood are about 30 percent of the costs for producing meranti.

The favourable qualities and light colour of rubberwood make it a good substitute for ramin (Gonystylus bancanus Baill.), a timber noted for its quality for furniture and other applications. The natural colour of rubberwood is one of the principal reasons for its popularity in Japan, where it is increasingly used to replace more traditional timbers, e.g. Fagus spp. and Quercus spp., in a wide variety of applications. A disadvantage of rubberwood is the smaller sizes available compared with timber from forest species. Boards normally have a maximum length of 1 800 mm and thickness of up to 50 mm. For larger end products such as table tops, the timber is usually laminated or fingerjointed.

Thailand's traditional relationship to Scandinavian markets via the teak trade has facilitated the introduction of Scandinavian design and quality concepts into rubberwood processing, which is resulting in products of high quality. Indonesia and Malaysia have also received assistance from Germany and other European countries in the development of rubberwood processing. Expertise and increasing investments from Japan, Taiwan Province of China and Singapore have assisted Southeast Asian production of furniture, furniture parts and other products for the East Asian, Australian and United States markets.

Rubberwood sawing and downstream processing industries in Peninsular Malaysia are well developed. In 1993, 116 stationary and 26 mobile sawmills - i.e. 20 percent of Malaysian sawmills - pro-cessed only rubberwood (MPI, 1993). In addition, rubberwood has been used as the raw material for a growing panel industry. At present, four particleboard mills, four moulded particleboard mills, one wood cement board mill and seven medium-density fibreboard mills use primarily rubberwood (Forestry Department, Peninsular Malaysia, 1998). Rubberwood is also still used for charcoal manufacturing and fuelwood.

The rubberwood sawntimber industry in Thailand is well developed, with a total of about 100 mills. Downstream rubberwood processing is experiencing very rapid growth, which is attributable in part to the depletion of the country's natural timber resource, the logging ban in natural forests and the diminishing supply of teak.

In Indonesia, attempts were made in the early 1980s to develop a rubberwood sawmilling industry to supply sawn-
timber to Singapore, Japan and Taiwan Province of China. Because of subsequent unfavourable government policies and regulations and a continuous demand for indigenous timbers, the industry did not develop significantly at that time. However, since the 1980s a rubberwood processing industry has been developing in Indonesia.

In the mid-1990s, some 20 percent of Malaysian sawmills processed only rubberwood



The large-scale export of rubberwood sawntimber and finished products (mainly furniture and indoor building components such as flooring and parquet) started from Malaysia in the early 1980s. The demand for and popularity of the timber and its products in traditional timber-importing countries such as Japan and the United States further stimulated the growth of the downstream processing industry in Malaysia (Hong, 1995). This growth, in turn, encouraged the development of similar rubberwood processing industries in the neighbouring countries of Indonesia and Thailand, in particular. In Malaysia, rubberwood has outperformed some of the traditional furniture timbers in export earnings. In 1994, exports of rubberwood furniture brought in US$297 million, accounting for 70 percent of Malaysia's furniture exports. In 1998, the country exported about US$683 million worth of rubberwood furniture (Table 4).

TABLE 4. Exports of rubberwood furniture by Malaysia (million US$)



















Source: Malaysian Timber Industry Board statistics cited in FDM Asia (1999).

Exports of sawn rubberwood from Malaysia increased from 903 m3 valued at US$35 000 in 1979 to 221 361 m3 valued at US$10.5 million in 1989, which indicates the tremendous interest and potential of this timber. In order to promote the development of the downstream rubberwood industry for added value, Malaysia introduced an export levy of 120 ringgit (M$) per cubic metre (US$33.3) on sawn rubberwood. This resulted in a decline in exports of the sawntimber to 103 478 m3, valued at US$13.3 million, in 1990 and to 71 261 m3, valued at US$11.9 million, in 1991. However, the levy achieved its goal: since exporting sawntimber was less advantageous and the export of further processed rubberwood products was not taxed, Malaysians invested in downstream processing. Together with the increasing international demand for rubberwood products, the levy thus triggered an investment boom in the Malaysian rubberwood industry as well as an increase in export of processed products (Table 4) which more than compensated for the reduced export of sawn rubberwood.

Since a large portion of the sawnwood produced in Thailand is processed and used locally (Ser, 1990), Thailand's exports of sawn rubberwood timber are insignificant when compared with those of Malaysia.

Some of the large international furniture companies, such as IKEA, have been sourcing rubberwood products from Malaysia since the early 1990s for distribution to their customers worldwide. Some of these large companies have linked up with furniture manufacturers to ensure that the supply of rubberwood products meets the companies' quality and design requirements; such linkages facilitate the transfer of technical skills and knowledge to local manufacturers.

Some confusion may be caused by the variety of names under which rubberwood is marketed. It has been called rubberwood, parawood, heveawood, hevaru, Malaysian ash and Malaysian oak. The latter two are misleading, giving the impression of similarity in properties to oak or ash. It would be beneficial to adopt a universally accepted common name for the timber to avoid wrong expectations by consumers. In the past it has been suggested that the name heveawood be used, but the industry has not adopted this suggestion, perhaps because of concerns for the industry's interests and profits.


Research has always been instrumental in the initiation and development of new technologies for industry. Rubberwood processing and utilization is no exception. As early as 1978, seven different research institutions and statutory bodies in Malaysia formed the Rubberwood Research Committee which significantly contributed towards the successful use of this resource. Major players were the Forest Research Institute Malaysia (FRIM), the Rubber Research Institute of Malaysia (RRIM) and the Standards and Industrial Research Institute of Malaysia (SIRIM), but the private sector was also involved. While many problems related to the processing of rubberwood have been overcome, research continues to be fundamental to the promotion and development of this industry.

Malaysia's exports of rubberwood sawntimber grew through the 1980s until an export levy on sawn rubberwood was introduced in 1990, which effectively stimulated investment in the downstream processing industry



Rubberwood has become established as a substitute for light tropical hardwoods and as one of the major timbers for the production of furniture and indoor building components.

The main reasons are its favourable timber and woodworking properties and the relatively low raw material costs since rubberwood is an agricultural by-product. This factor makes the timber highly competitive in comparison with timber from forest species which have comparably high raw material costs. An additional asset is its "green" aspect: rubber trees have to be removed for replanting once the latex yield has declined to uneconomical levels. Rubber plantations are now managed in a sustainable
manner. The acceptance of rubberwood as a sustainable, plantation-grown, "environmentally friendly" timber has contributed to its universal appeal.

Strong research and aggressive marketing have contributed towards making rubberwood one of the most important Southeast Asian export timbers. It remains to be seen whether the increasing plantation area in Southeast Asia will be sufficient to meet the growing demand for rubberwood products. 


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