Tualang

Tualang Wood: A Durable Choice for Heavy-Duty Construction

Introduction
Tualang wood, derived from Koompassia excelsa, is a medium hardwood known for its reddish-brown to chocolate-brown color. Commonly found in Malaysia and known by various names such as Kayu Raja in Sarawak and Mengaris in Sabah, tualang wood is valued for its strength and durability, making it a preferred choice for heavy construction and furniture.

Key Characteristics

• Density: A Medium Hardwood with a density of 800-865 kg/m³, tualang wood offers robust strength for structural applications.

• Durability: Classified as moderately durable under exposed conditions. However, the sapwood is prone to insect and fungal attacks, while the heartwood is vulnerable to termites.

• Texture: The texture is coarse but even, with deeply interlocked grain that enhances its strength.

Strength Properties

Tualang wood belongs to Strength Group A, making it suitable for heavy-duty projects. Its excellent strength properties ensure durability and longevity in various construction uses.

Applications

Tualang wood is highly versatile and suitable for a range of industrial and construction applications:

• Heavy Construction: Ideal for posts, beams, joists, columns, piling, and railway sleepers. Treated tualang is also used for power transmission poles.

• Flooring & Furniture: It is an excellent choice for heavy traffic flooring and heavy-duty furniture due to its strength and aesthetic appeal.

• Tool Handles: The impact-resistant qualities make it suitable for crafting durable tool handles.

• Other Uses: Fender supports, office and shop fittings, mouldings, and panelling.

Drying & Machining Properties

• Air Drying: Tualang wood dries moderately slowly, with 13 mm thick boards taking 3.5 months and 38 mm boards taking 6 months to air dry. The main concerns during drying are end-checking, surface-checking, and insect attacks.

• Machining: Tualang is relatively easy to resaw, cross-cut, and plane when green, though it becomes slightly more difficult when dry. The planed surface is generally smooth or moderately smooth.

Nailing & Shrinkage

• Nailing: Tualang wood has good nailing properties, making it easy to work with on-site.

• Shrinkage: Average shrinkage, with radial shrinkage at 1.5% and tangential shrinkage at 1.7%, ensures dimensional stability during the drying process.

Conclusion

Tualang wood, with its balance of strength, durability, and versatility, is a reliable option for heavy-duty construction, flooring, and furniture. Its ability to withstand demanding environments makes it an ideal timber for projects that require both functionality and aesthetic value.

INTRODUCTION

The Standard Malaysian Name for the timber of Koompassia excelsa (Leguminosae). Vernacular names applied include kayu raja (Sarawak), mengaris (Sabah) and tapang (Sarawak). This is a monospecific timber. The sapwood is buff-coloured or yellow-brown, often with a pink tinge and is sharply differentiated from the heartwood, which is reddish brown to deep brick-red-brown when fresh and darkens with age to a deep chocolate-brown.  

Also known as Mengaris (Brunei); Bengaris, Mengaris, Menggeris, Sialang, Tualang and Wehis (Indonesia); Koompassia (Papua New Guinea); Ginoo and Manggis (Philippines); and Tulae and Yuan (Thailand).

DENSITY

The timber is a Medium Hardwood with a density of 800-865 kg/m3 air dry.

NATURAL DURABILITY

Tualang is classified as moderately durable under exposed conditions. The durability rating is based on the standard graveyard tests conducted at the Forest Research Institute Malaysia (FRIM) on specimens of dimension 50 mm x 50 mm x 600 mm. In the first series of such tests, all 6 specimens were completely destroyed after 3.5 years (Foxworthy & Woolley, 1930). In the second test, 60 specimens were used and the average service life was 3 years (Jackson, 1965). The sapwood of the timber is susceptible to both powder-post beetle and fungi attacks, while the heartwood is readily destroyed by termites.

PRESERVATIVE TREATMENT

The timber is amenable to preservative treatment and is classified as easy to treat.

TEXTURE

Texture is rather coarse but even except in areas where included phloem occurs. Grain is interlocked, often deeply interlocked. 

STRENGTH PROPERTIES

The timber falls into Strength Group A (Engku, 1988b) or SG 3 (MS 544:Part 2:2001).

Strength Properties of Tualang 

MACHINING PROPERTIES

It is easy to resaw and cross-cut when green but is slightly difficult to resaw when dry. Planing is easy in either condition and the surface produced is smooth to moderately smooth.

Machining Properties of Tualang

NAILING PROPERTY

Nailing property is rated as good.  

AIR DRYING

The timber dries moderately slowly to slowly with slight end-checking, surface-checking and insect attacks as the main sources of degrade. 13 mm thick boards take 3.5 months to air dry, while 38 mm thick boards take 6 months.

KILN-DRYING

Kiln Schedule E is recommended.

Kiln Schedule E 

SHRINKAGE

Shrinkage is average, with radial shrinkage averaging 1.5% and tangential shrinkage averaging 1.7%.

DEFECTS

The major defect that is associated with the timber of tualang is the presence of hard abnormal tissues commonly known as included phloem. It is observed that tualang is even more severely riddled with included phloem than kempas (Koompassia malaccensis). In sawn timber, bands and patches of included phloem similar to those found in kempas can often be seen (Ser, 1981). These zones of abnormal tissues are likely to result in seasoning degrade and mechanical weakness in the timber. Some minor defects that have been recorded are shot holes, pin holes, heart rot and hollow pith. Apart from these, the logs of freshly-felled K. excelsa are generally free from other defects.

USES

When treated, the timber is suitable for all heavy construction, like posts, beams, joists, columns (heavy duty), piling, railway sleepers and power transmission poles. Untreated, the timber is suitable for flooring (heavy traffic), panelling, mouldings, heavy duty furniture, fender supports, office and shop fittings, tool handles (impact) and plywood.