Discover Petai wood: A Versatile Wood for Interior Works and Beyond
Petai wood, scientifically known as Parkia spp. (Leguminosae), is a distinctive wood species native to Malaysia. It is commonly referred to by various vernacular names such as “kupang” in Sabah, “kerayong” in Peninsular Malaysia, and “petai” in Peninsular Malaysia and Sarawak. Notable species within this genus include P. timoriana, P. singularis, and P. speciosa. The sapwood is notably wide and ranges from white to yellow-brown in color, while the heartwood is rarely developed but, when present, is dark brown.
Petai wood is also known in neighboring regions as Petai (Brunei), Ro Yong (Cambodia), Olimbopo, Petai, and Soga (Indonesia), and Sa To (Thailand).
Key Characteristics of Petai Wood
- Density: Petai wood is classified as light to moderately heavy, with a density ranging from 415 to 815 kg/m³ when air-dried. This places it within the Light Hardwood category in Malaysia.
- Natural Durability: Durability tests on P. speciosa conducted by the Forest Research Institute Malaysia (FRIM) show a natural lifespan of 1 year, making it non-durable. However, when treated with creosote, the wood has been found to last up to 15 years, based on a graveyard test conducted by Tam (1983).
- Preservative Treatment: Petai wood is highly receptive to preservative treatments, which can extend its lifespan significantly.
- Texture: The texture is coarse and uneven, with a straight to shallowly interlocked grain pattern.
- Strength Properties: Petai falls under Strength Group D (Burgess, 1958) or SG5 (MS 544
2:2001), indicating that while it is not the strongest, it is still suitable for light-duty applications.
Strength Properties of Petai Wood (P. speciosa)
| Test Condition | Modulus of Elasticity (MPa) | Modulus of Rupture (MPa) | Compression Parallel to Grain (MPa) | Shear Strength (MPa) |
| Green | 9,600 | 49 | 24.3 | 8.3 |
| Air Dry | 10,700 | 55 | 30.8 | 7.4 |
Machining Properties
Petai wood is easy to work with, and machining it produces a smooth, planed surface. Below are the machining properties under different conditions:
| Machining Properties (P. speciosa) | Sawing | Planing | Boring | Turning | Re-sawing | Cross Cutting |
| Green | Easy | Easy | Easy | Smooth | Easy | Rough |
| Air Dry | Easy | Easy | Easy | Smooth | Easy | Rough |
Nailing Properties
The nailing properties of Petai wood are rated as excellent, making it an ideal choice for projects that require easy assembly.
Drying and Shrinkage
- Air Drying: Petai wood seasons at a moderate pace, with some risk of defects like end-checking, insect and fungal attacks, and slight warping. Boards of 13 mm thickness take about 3.5 months to air dry, while 38 mm thick boards take around 5 months.
- Shrinkage: Petai wood exhibits low shrinkage rates, with radial shrinkage averaging 1.1% and tangential shrinkage averaging 1.9%.
Defects
Petai wood are generally free from common defects like “spongy heart” or borer damage, though they can be knotty near the pith. Desch (1941) noted that samples of this wood in the Kepong collection were infected with blue-stain fungi, and some were attacked by powder-post beetles. However, it was also observed that P. javanica is rarely affected by borers.
Application
Though Petai wood is more famous for its edible fruits, its wood has found its way into various industries. It has been used successfully in the production of plywood, packing boxes, and crates. Additionally, the wood is suitable for interior applications such as partitioning, stair railings, skirtings, and furniture. It is also popular in joinery, cabinet making, and for temporary light construction projects, including the production of disposable chopsticks.
