Kulim Wood: A Versatile Medium Hardwood for Various Applications

Kulim wood , known scientifically as *Scorodocarpus borneensis* (Olacaceae), is a notable wood species in Malaysia. Commonly referred to as “bawang hutan” in Sabah and Sarawak, and “ungsunah” in Sarawak, this monotypic wood is characterized by its light yellow sapwood, distinctly separated from its dark purple-brown to dark red-brown heartwood.

 

Kulim is also recognized by various names in other regions:

– **Indonesia:** Bawan, Kasino, Kayu bawang, Kulim, Madudu, Sinduk

– **Thailand:** Krathiam ton, Kuleng, Kulim

 

**Density**

 

Kulim is classified as a Medium Hardwood with a density ranging from 640 to 975 kg/m³ when air-dried.

 

**Natural Durability**

 

Kulim wood is considered moderately durable under Malaysian conditions. This classification is based on standard graveyard tests conducted at the Forest Research Institute Malaysia (FRIM), which revealed an average service life of 4 years for untreated specimens of 50 mm x 50 mm x 600 mm dimensions.

 

Kulim wood is immune to powder post beetle attacks but susceptible to ambrosia beetles and rot. Termite attacks are not severe, and the wood is resistant to marine borers. In Port Klang trials, untreated specimens of 13 x 13 cm and 13 x 26 cm remained serviceable for 2-3 and 4-5 years, respectively. Treated specimens of the same dimensions, treated with 107 kg/m³ absorption of 50/50 creosote and diesel fuel by the open tank method, lasted 3-5 years.

 

**Preservative Treatment**

 

Kulim wood is classified as average in amenability to preservative treatment.

 

**Texture**

 

The texture of Kulim is moderately fine and even, with a shallow to deeply interlocked grain.

 

**Strength Properties**

 

Kulim wood falls into Strength Group B (Engku, 1988) or SG 3 (MS 544: Part 2: 2001).

 

**Strength Properties of Kulim**

 

| Test Condition | Modulus of Elasticity (MPa) | Modulus of Rupture (MPa) | Compression Parallel to Grain (MPa) | Compression Perpendicular to Grain (MPa) | Shear Strength (MPa) |

|—————-|—————————–|—————————|————————————-|——————————————|———————–|

| Green          | 13,300                      | 78                        | 44.4                                | 4.48                                     | 8.8                   |

| Air dry        | 14,900                      | 107                       | 57.0                                | 5.10                                     | 10.3                  |

 

**Machining Properties**

 

Kulim is slightly difficult to resaw and easy to slightly difficult to cross-cut. The air-dried wood is slightly difficult to plane but results in a smooth finish.

 

**Machining Properties of Kulim**

 

| Test Condition | Sawing           | Planing         | Boring           | Turning         | Re-sawing       | Cross Cutting  | Ease of Planing  | Quality of Finish  | Ease of Boring   | Quality of Finish  | Ease of Turning  | Quality of Finish |

|—————-|——————|—————–|——————|—————–|—————–|—————-|——————|——————-|——————|——————-|——————|——————-|

| Green          | Slightly difficult | Easy            | Easy             | Smooth          | Easy            | Smooth         | –                | –                 | –                | –                 | –                | –                 |

| Air dry        | Difficult         | Slightly difficult | Slightly difficult | Smooth         | Slightly difficult | Smooth        | Moderately easy  | Slightly rough    | –                | –                 | –                | –                 |

 

**Nailing Property**

 

The nailing property of Kulim wood is rated as very poor.

 

**Air Drying**

 

Kulim seasons fairly rapidly, with moderate end-checking and splitting and slight surface-checking as the primary sources of degrade. Thirteen mm thick boards take 2 months to air dry, while 38 mm thick boards take 4 months.

 

**Shrinkage**

 

Kulim exhibits fairly high shrinkage, with radial shrinkage averaging 1.7% and tangential shrinkage averaging 3.2%.

 

**Defects**

 

Kulim logs are generally free from defects except for a defective core.

 

**Uses**

 

Kulim wood is suitable for:

– Medium construction under cover

– Posts, beams, joists, rafters

– Door and window frames and sills

– Bridges and tool handles (impact)

– Marine environments due to resistance to marine borers

– Ship and boat building (keels, keelsons, and framework)

– Flooring

– Railway sleepers

– Cooling towers (structural members)

– Columns (light duty)

– Telegraphic and power transmission posts and cross arms (when treated with preservatives)

 

Kulim wood’s versatility and durability make it an excellent choice for various construction and industrial applications. Explore the potential of Kulim wood for your projects at Creawood, where quality meets expertise.