Darwin stringybark

Darwin stringybark's heartwood is pale reddish-brown with wide sapwood similar to forest red gum. Density (990-1200) kgm3 being hard, heavy and stiff, with exceptionally good impact properties comparable to the ironbarks.

Other Names

No other published names are in use

Botanical Name

Eucalyptus tetrodonta

Common Form
Sawn

Sapwood pale yellow or white, fairly wide and not always clearly demarcated from the reddish-brown or pale red heartwood.  Texture (referring to vessel size) medium.  Grain mainly straight.  The figure is not prominent, and growth rings occasionally tending to distinct. The species is widely distributed through northern Australia from Queensland to Western Australia north of latitude 16oS; trees grow from close to sea level up to 300m.  Best growth occurs on moderately deep, well drained sandy soils.  Represents one of the larger species in the Northern Territory which produces good milling timber.  The species is also recommended for tropical forestry.  

Suitability for pulp and paper and composites:

The basic density of the species is higher than what paper manufacturers generally desire, and CSIRO studies have indicated that pulp yields from natural stands are low. The high basic density also makes the species less desirable for composite wood products such as laminated veneer lumber and medium density fibreboard but quite suitable for solid-wood products.

Wood characteristics:

Timber is of high density similar to that of the ironbarks making it hard, heavy and stiff, with exceptionally good impact properties.  It is not easy to work with machine operations and it is difficult to cut with hand tools.  Material tends to ride on planer cutters; straighter grain usually produces good surfaces.  A 15o cutting angle is recommended for stock with interlocked grain.  Quartersawn boards dry fairly rapidly provided mild drying schedules are used.  The timber is fissile (easy to split), and glues fairly well.  Wearing and weathering properties are good.  Sapwood is lyctus susceptible, heartwood occasionally attacked by termites.  Sapwood is probably permeable, but the heartwood is extremely difficult to impregnate.  The wood is often used in hewn or as rounds.

REFERENCES:

1  W.G. Keating and E. Bolza. (1982) Characteristics, properties and uses of timbers. Vol. 1., South-east Asia, Northern Australia and the Pacific. Inkata Press

2  W.J. Smith, W.T. Kyneston, M.L. Cause and J. G. Grimmett (1991) Building timbers.  Technical Pamphlet No. 1, Queensland Forest Service, Department of Primary Industries 

3  B. Budgeon (1981)/ The shrinkage and density of some Australian and South-East Asian timbers.  Tech paper (2nd series) No. 38, Division of Building Research, CSIRO, Australia

4  E. Bolza and N.H. Kloot (1963) The mechanical properties of 174 Australian timbers.  Tech paper No. 25, Division of Building Research, CSIRO, Australia 

5  T. J. Venn (2003) Potential markets for logs and sawn timber from Darwin stringybark forests of Cape York Peninsula.  Marketing of farm-grown timber in tropical North Queensland : conference proceedings, 18 June 2003

FOOTNOTES:

SHRINKAGE - tangential and radial shrinkages after reconditioning, Values before reconditioning are slightly higher indicating low degree of wood collapse

DENSITY - Seasoned - after reconditioning

MOISTURE CONDITION - No specific data is available for seasoned material.  The seasoned values shown are estimated from corresponding green values from the Strength grouping classification as per (Ref 1)

 

Shrinkage

Very Low Low Medium High Very High

Tangential :

4.90%

Radial :

Unit Movement Tangential:

3.80%

Unit Movement Radial:

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

S8

Seasoned:

SD1

SD2

SD3

SD4

SD5

SD6

SD7

SD8

Stress Grade

Structural
No. 1
Structural
No. 2
Structural
No. 3
Structural
No. 4
Structural
No. 5

Unseasoned:

F22

F22

F17

F14

F11

Seasoned:

F34

F27

F22

F17

F14

Density per Standard

Seasoned:

1090kg/m3

Unseasoned:

0kg/m3

Joint Group

Very High

High

Reasonably High

Medium

Low

Very Low

Unseasoned:

J1

J2

J3

J4

J5

J6

Seasoned:

JD1

JD2

JD3

JD4

JD5

JD6

Colour

  White, yellow, pale straw to light brown Pink to pink brown Light to dark red Brown, chocolate, mottled or streaky
   

Mechanical Properties

Modulus of Rupture - Unseasoned:

145

Modulus of Rupture - Seasoned:

108

Modulus of Elasticity - Unseasoned:

16.3

Modulus of Elasticity - Seasoned:

18.7

Maximum Crushing Strength - Unseasoned:

73.8

Maximum Crushing Strength - Seasoned:

81

Impact - Unseasoned:

73.8

Impact - Seasoned:

Toughness - Unseasoned:

High - 25 Nm and above

Toughness - Seasoned:

High - 25 Nm and above

Hardness - Unseasoned:

9.5

Hardness - Seasoned:

Durability

Low Moderate Reasonably High High
(0 - 5 yrs) (5 - 15 yrs) (15 - 25 yrs) (more than 25 yrs)

In-Ground:

(0 - 7 yrs) (7 - 15 yrs) (15 - 40 yrs) (More than 40 yrs)

Above ground:

(0 - 20 yrs, usually < 5) (21 - 40 yrs) (41 - 64 yrs) (More than 60 yrs)

Marine Borer Resistance:

Lyctid Borer Susceptibility:

Susceptible

Lyctid Borer Susceptibility - Other:

Termite Resistance:

Resistant

Fire Properties

Appearance

Sapwood pale yellow or white, fairly wide and usually clearly demarcated from the reddish-brown or pale red heartwood.  Texture (referring to vessel size) medium.  Grain mainly straight.  The figure is not prominent, and growth rings occasionally tending to distinct.

Common Applications

Heavy structural; heavy flooring; mine timber; ship and boat building; handles and ladders; agricultural implements; joinery; sleepers; poles and piles; cross arms.

Workability

It is not easy to work with machine operations and it is difficult to cut with hand tools.  Material tends to ride on planer cutters; straighter grain usually produces good surfaces.  A 15o cutting angle is recommended for stock with interlocked grain.

Origin of timber
QLD
On Cape York Peninsula there are about 1.7 Mha of eucalypt forests with commercially attractive timber species on land tenures other than National Park.
The Queensland Department of Primary Industries - Forestry (DPI-Forestry) considers the stands of timber in the Darwin stringybark (Eucalyptus tetrodonta) forests on Cape York Peninsula (CYP) to be the largest remaining forest resource in Queensland.
Source of timber
Native Forest
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