Goldfields blackbutt is a small to medium-sized tree up to 12 m tall, often with a short trunk. The dark rough bark at the base changes to smooth white, often powdery bark.
Heartwood is chocolate-brown, with an attractive grain.
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 1180 kg/m3, air-dry density about 1130 kg/m3, and basic density about 880 kg/m3.
Tangential and radial shrinkage are about 5.5 and 4.2 per cent respectively.
Goldfields craftsmen rate blackbutt as good for turning, machinability, boring, screwholding, stability and gluing, and excellent for sanding and finishing.
The CSIRO Durability Classes are based on the performance in ground of outer heartwood when exposed to fungal and termite attack.
Class | Life Years |
---|---|
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 wood is durable, and presumably CSIRO Durability Class 2.
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
Strength Property | S1 | S2 | S3 | S4 | S5 | S6 | S7 |
---|---|---|---|---|---|---|---|
MOR | 103 | 86 | 73 | 62 | 52 | 43 | 36 |
MOE | 16300 | 14200 | 12400 | 10700 | 9100 | 7900 | 6900 |
MCS | 52 | 43 | 36 | 31 | 26 | 22 | 18 |
Minimum values (Mpa) for green timber
Strength Property | SD1 | SD2 | SD3 | SD4 | SD5 | SD6 | SD7 | SD8 |
---|---|---|---|---|---|---|---|---|
MOR | 150 | 130 | 110 | 94 | 78 | 65 | 55 | 45 |
MOE | 21500 | 18500 | 16000 | 14000 | 12500 | 10500 | 9100 | 7900 |
MCS | 80 | 70 | 61 | 54 | 47 | 41 | 36 | 30 |
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 (S2) and (SD2). The brackets indicate conservative provisional ratings based on the air-dry density. The more important strength properties based on the strength groups are given in the table below..
Property | Units | Green | Dry |
---|---|---|---|
Modulus of Rupture | MPa | 86 | 130 |
Modulus of Elasticity | MPa | 14200 | 18500 |
Max Crushing Strength | MPa | 43 | 70 |
Hardness | KN | - | - |
Limited availability because of the scattered nature of the resource.
Uses during the gold rushes were for mining timber and fuelwood. The timber has potential for flooring and parquetry, general craftwork and specialty furniture.