Marri is commonly referred to as 'red gum'. Marri is usually a medium sized to tall tree up to 40 m in height with flaky grey bark, widely distributed in the south-west of Western Australia in the jarrah and karri forests. It extends from north of Geraldton southwards to Cape Riche, and eastwards to beyond Narrogin in the Wheatbelt.
Heartwood is pale yellow to light brown to reddish brown, with sapwoodbands up to 40 mm wide, usually sufficiently paler to be distinguishable from the heartwood.
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 1200 kg/m3, air-dry density about 850 kg/m3, and basic density about 650 kg/m3.
Tangential and radial shrinkage before reconditioning are 6.5 and 3.5 per cent respectively, and after reconditioning 5.6 and 3.4 per cent respectively.
Workability is good, with the timber being relatively easy to work, and nailing satisfactory.
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.:
Durability Class based on the CSIRO 1996 ratings is 4/3 for decay and 4/3 for combined decay + termites. Sapwood is Lyctus-susceptible.
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 S3 and SD3. The more important timber properties are given in the table below.
|Modulus of Rupture||MPa||78||125|
|Modulus of Elasticity||MPa||14000||17000|
|Max Crushing Strength||MPa||41||66|
Although there is a large resource in native forests, timber is available in small quantities only because of the incidence of kino veins. It is limited to Western Australia.
Uses are more restricted than for many other species. Sawmill recoveries are low because of the extensive occurrence of kino or gum veins. There is an increasing market for ' feature grade' timber for furniture use. The timber has been used in general construction, case manufacture, tool handles, sporting goods and oars. Preservative treated material is useful for piles, poles and fence posts.