Introduction

 

Kapur, the Standard Malaysian Name for the timber of Dryobalanops spp. (Dipterocarpaceae), is a prominent hardwood found in Peninsular Malaysia, Sabah, and Sarawak. Commonly referred to as kapur, keladan, or kelansau, the major species include D. aromatica, D. beccarii, D. keithii, D. lanceolata, D. oblongifolia, and D. rappa. The sapwood is yellowish-brown, distinctly separated from the reddish-brown heartwood.

 

Also known as Kapur (Brunei) and Kamper, Kapur, and Petanang (Indonesia).

 

Density

 

Kapur is classified as a Medium Hardwood with an air-dry density of 580-820 kg/m³.

 

Natural Durability

 

Kapur timber is generally not durable. Standard graveyard tests conducted by the Forest Research Institute Malaysia (FRIM) revealed an average service life of 1.9 years for D. oblongifolia and 6.0 years for D. aromatica. While both species resist fungal attacks, they are susceptible to termites.

 

Preservative Treatment

 

Kapur timber is challenging to treat with preservatives, making it difficult to enhance its natural durability.

 

Texture

 

The texture of kapur is moderately coarse and even, with a straight to interlocked grain.

 

Strength Properties

 

Kapur timber falls into Strength Group B (Engku, 1988b) or SG 4 (MS 544: Part 2: 2001).

 

| Species           | Test Condition | Modulus of Elasticity (MPa) | Modulus of Rupture (MPa) | Compression parallel to grain (MPa) | Compression perpendicular to grain (MPa) | Shear strength (MPa) |

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

| D. aromatica      | Green          | 15,900                      | 84                        | 46.5                                | 4.2                                       | 8.4                   |

|                   | Air dry        | 18,700                      | 114                       | 61.7                                | 5.5                                       | 10.5                  |

| D. oblongifolia   | Green          | 13,200                      | 73                        | 39.2                                | 5.1                                       | 8.1                   |

|                   | Air dry        | –                           | –                         | –                                   | –                                         | –                     |

 

Machining Properties

 

The timber of D. rappa is easy to work with, while other species range from moderately easy to slightly difficult.

 

| Species         | Test Condition | Sawing                | Planning     | Boring      | Turning        |

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

| D. aromatica    | Green          | Moderately easy       | Easy         | Easy        | Moderately smooth |

|                 | Air dry        | Easy                  | Easy         | Easy        | Moderately smooth |

| D. oblongifolia | Green          | Easy to slightly difficult | Easy     | Easy        | Rough          |

|                 | Air dry        | Slightly difficult    | Easy         | Easy        | Moderately smooth |

 

Nailing Property

 

Nailing properties vary; it is good in D. rappa but poor in other species.

 

Air Drying

 

Kapur timber dries moderately slowly to slowly, with minimal degrade. The drying times and properties for some species are summarized below:

 

| Species       | Time to air dry (months) | Remarks |

|—————|————————–|———|

|               | 13 mm thick boards | 38 mm thick boards |

| D. aromatica  | 2                      | 5                     | Fairly slow drying; moderate end-splitting; splitting and surface-checking. |

| D. rappa      | 4                      | 6                     | Slow drying; moderate cupping due to very high differential shrinkage. |

 

Kiln-Drying

 

Kiln Schedule E is recommended for kapur. Proper stacking is crucial to prevent cupping. 25 mm thick boards typically take 14 days to kiln-dry.

 

| Moisture Content (%) | Temperature (Dry Bulb) | Temperature (Wet Bulb) | Relative Humidity (%) |

|———————-|————————|————————|———————–|

| Green                | 120°F (48.5°C)         | 115°F (46°C)           | 85                    |

| 60                   | 120°F (48.5°C)         | 113°F (45°C)           | 80                    |

| 40                   | 125°F (51.5°C)         | 116°F (46.5°C)         | 75                    |

| 30                   | 130°F (54.5°C)         | 117°F (47°C)           | 65                    |

| 25                   | 140°F (60°C)           | 120°F (49°C)           | 55                    |

| 20                   | 155°F (68°C)           | 127°F (53°C)           | 45                    |

| 10                   | 170°F (76.5°C)         | 136°F (58°C)           | 40                    |

 

Shrinkage

 

Shrinkage properties of kapur are:

 

| Species          | Shrinkage (%) (Green to air dry) | Remarks                             |

|——————|———————————-|————————————-|

|                  | Radial   | Tangential            |

| D. aromatica     | 2.1      | 4.6                   | Very high shrinkage.                |

| D. oblongifolia  | 1.7      | 3.8                   | High shrinkage.                     |

| D. rappa         | 1.5      | 5.1                   | Very high differential shrinkage.   |

 

Defects

 

The most common defect in kapur timber is pin-holes, more frequently found in D. aromatica than in D. oblongifolia. These are caused by small ambrosia beetles, typically beginning in the living tree and not continuing in seasoned wood. Occasionally, logs may have spongy heart, but it is usually insignificant.

 

Uses

 

Kapur is suitable for various applications, including:

– Medium construction

– Posts, beams, joists, rafters

– Door and window frames and sills

– Fender supports

– Telegraphic and power transmission posts and cross arms

– Flooring

– Staircase components (treads, angle blocks, rough brackets, bullnose, riser, balustrade, carriage, stringers, round end, and winder)

– Vehicle bodies (framework, floorboards, and planking)

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

– Pallets (heavy and permanent types)

– Tool handles (impact)

– Cooling tower structural members

– Plywood

– Laboratory benches

– Light-duty columns

– Railway sleepers

 

For domestic flooring and internal fittings where finished appearance is crucial, care should be taken to avoid contact with iron nails, screws, or other fittings to prevent unsightly black stains.

 

Kapur timber’s versatility and strength make it a valuable resource for a wide range of construction and manufacturing applications. At Creatimber, we are committed to providing high-quality kapur and other timber species to meet your project needs. Explore our extensive product range and discover the benefits of using kapur in your next project.