WA blackbutt

Eucalyptus patens

WA blackbutt has the common name ‘yarri’. WA blackbutt is usually a tall tree up to 45 m in height, with diameter at breast height to 1.8 m and a relatively large straight bole. On less favourable, particularly swampy sites, it is a smaller tree of poor form. It has a natural distribution that coincides closely with that of jarrah (E. marginata), from near Perth in the north to Albany on the south coast.

Wood description [more info]
Heartwood is pale yellowish-brown, and the sapwood is sufficiently paler to be distinguishable.

Wood density [more info]
Green density is about 1120 kg/m3, air-dry density about 850 kg/m3, and basic density about 690 kg/m3.

Shrinkage [more info]
Tangential and radial shrinkage before reconditioning are 10.0 and 5.0 per cent respectively, and after reconditioning 7.0 and 3.5 per cent respectively.

Workability [more info]
The timber is relatively easy to work, although interlocked grain can make it difficult.

Durability [more info]
Durability Class based on the CSIRO 1996 ratings is 2 for decay, and 4 for decay + termites. Sapwood is Lyctus-susceptible.

Strength group and properties [more info]
Green and dry strength groups are S4 and SD5. The more important strength properties are given in the table below.

Property Units Green Dry
Modulus of Rupture MPa 66 99
Modulus of Elasticity MPa 12000 13000
Max Crushing Strength MPa 37 65
Hardness KN 5.5 6.9

Uses [more info]
Blackbutt’s main use has been in flooring, although in the past it was used for general construction, case manufacture, sleepers, flooring and panelling.

Availability [more info]
Availability is limited, because a large part of the resource is now conserved in stream reserves. The timber is available in small quantities in Western Australia.

Source : Forest Products Commission WA