Merbatu Wood: A Comprehensive Overview

Introduction

Merbatu is the Standard Malaysian Name and the ASEAN Standard Name for the wood of various species including Atuna spp., Kostermanthus spp., Licania spp., Maranthes corymbosa, and Parinari spp. (Chrysobalanaceae). The trees are also known by several other vernacular names such as kemalau (Peninsular Malaysia), kukut (Sarawak), mentelor (Peninsular Malaysia), merbatu laut (Peninsular Malaysia), merbatu pipit (Peninsular Malaysia), nyalin laut (Sarawak), rasak batu (Sabah and Sarawak), and torog (Sabah). Key species include Atuna cordata, A. nannodes, A. racemosa, Kostermanthus heteropetalus, Maranthes corymbosa, Parinari costata, P. elmeri, P. oblongifolia, P. rigida, and P. rubiginosa. The sapwood is lighter in color but not distinctly separated from the heartwood, which ranges from red-brown to sometimes a yellow tinge.

This wood is also recognized as Sa (Fiji); Kayu batu, Kepala tupai, Kolaka, and Merbatu (Indonesia); Phok (Laos); Tauk-kade (Myanmar); Busu plum (Papua New Guinea); Baritadiang and Liusin (Philippines); and Chi khat phen, Chi ot phen, Mak Mu, and Maphok (Thailand).

Density
Merbatu wood is categorized as a Medium Hardwood, with a density ranging from 685-1,000 kg/m3 when air-dried.

Natural Durability
Merbatu wood is moderately durable when exposed to the elements but responds well to preservative treatment.

Texture
The texture of Merbatu wood is moderately coarse but even, with a straight, spiral, or wavy grain.

Strength Properties
Merbatu wood is classified into Strength Group B (Burgess, 1958) or SG 2 (MS 544:Part 2:2001), indicating strong mechanical properties.

Machining Properties
Merbatu wood can be difficult to very difficult to resaw and cross-cut due to the presence of silica and twisted grain. However, it is only slightly difficult to plane, producing a smooth surface when properly machined.

Nailing Property
The nailing property of Merbatu wood is rated as very poor, requiring careful handling.

Air Drying
Merbatu wood seasons relatively quickly but with some minor defects. Slight cupping, bowing, splitting, and moderate amounts of end-checking and staining are common issues. 13 mm thick boards take approximately 1.5 months to air dry, while 38 mm thick boards take about 3.5 months.

Shrinkage
Shrinkage in Merbatu wood is fairly low, with radial shrinkage averaging 1.6% and tangential shrinkage averaging 2.6%.

Uses
Merbatu wood is versatile and suitable for a wide range of applications, including:
– Medium to heavy construction under cover
– Posts, beams, joists, and rafters
– Light duty columns
– Door and window frames and sills
– Permanent and heavy-duty pallets
– Staircase carriages
– Saltwater piling and other marine constructions
– Railway sleepers for secondary lines
– Vehicle bodies (framework, floorboards, and planking)
– Flooring for heavy traffic
– Telegraphic and power transmission posts and cross arms

Merbatu wood’s combination of strength, durability, and aesthetic qualities make it an excellent choice for various construction and industrial applications.