Brown mallet is a small to medium-sized tree, 10-25 m in height and with diameter at breast height (dbh) to 0.7 m, occasionally up to 30 m tall and diameter 1 m. Found in south-west Western Australia on the drier, inland side of the jarrah (E. marginata) forest, in the 300 to 400 mm rainfall zone. It occurs from north-west of York to Narrogin and Wagin, south to GMT Barker and east to near Kondinin, Lake Grace and Ravensthorpe. About 8000 ha of plantations were established near Narrogin.
Heartwood is light red-brown to dark grey-brown, with reddish streaks, and the sapwood is up to 30 mm wide and distinctly paler.
Green density is the density of wood in the living tree, defined as green mass divided by green volume, and useful for estimating transport costs. It varies with season and growing conditions.
Air-dry density is the average mass divided by volume at 12 per cent moisture content (this is the average environmental condition in the coastal capital cities around Australia).
Basic density is oven-dry mass divided by green volume. This measure has the advantage that moisture content variations in the tree during the year are avoided.:
Green density is about 1120 kg/m3, air-dry density about 980 kg/m3, and basic density about 770 kg/m3 (published figures). In comparison, CALM Timber Technology measured 1130 kg/m3, 1090 kg/m3 and 865 kg/m3 for the three densities.
Tangential and radial shrinkage before reconditioning are 7.1 and 5.5 per cent respectively, and after reconditioning 4.4 and 3.6 per cent respectively.
With workability, the timber is rather hard to work but dresses well. The grain is often interlocked and the timber is easy to dry.
The CSIRO Durability Classes are based on the performance in ground of outer heartwood when exposed to fungal and termite attack.
|1||More than 25|
|2||15 to 25|
|3||8 to 15|
|4||Less than 8|
The ratings are not relevant to above-ground use. In late 1996, CSIRO published revised ratings, which include termite susceptibility. Ratings are now available for about seventy species for decay, and for decay plus termites.:
The Durability Class based on the CSIRO 1996 ratings is 2/1 for <decay, and 2 for decay + termites.
Minimum values (MPa) for strength groups for green and seasoned timber come from Australian Standard AS2878-1986 'Timber - Classification of strength groups'. In grading structural timber, each species is allocated a ranking for green timber of S1 (strongest) to S7, and for seasoned timber SD1 (strongest) to SD8.
MOR is modulus of rupture or bending strength, MOE is modulus of elasticity or 'stiffness', and MCS is maximum crushing strength or compression strength. Hardness refers to the Janka hardness test and is a measure of resistance to indentation.
Minimum values (Mpa) for green timber
Minimum values (Mpa) for green timber
Where test data were available, they are shown in bold print. Most values are from Bootle (1983), Wood in Australia. Types, properties and uses. (McGraw-Hill), or Julius (1906), 'Western Australian timber tests 1906: The physical characteristics of the woods of Western Australia'.
Where no strength data were available, air-dry density was used in accordance with the Australian Standard AS2878-1986 Timber - Classification of strength groups to predict the strength group. Consequently, the strength values quoted are from the above two tables.:
Green and dry strength groups are S1 and SD2. The more important strength properties are given in the table below.
|Modulus of Rupture||MPa||113||179|
|Modulus of Elasticity||MPa||15000||19000|
|Max Crushing Strength||MPa||53||94|
There is limited availability in Western Australia, and timber is generally marketed around the Narrogin area.
Uses have been for general construction (particularly on farms), tool handles, mining timbers and fuel. The bark has high tannin content (40 per cent or more), and this could be used for tanning leather and for adhesives manufacture.