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Across the grain
The direction at right angles to the length of the fibres and other longitudinal elements of the wood.

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Yellow Gum | Eucalyptus leucoxylon

Yellow Gum timber is yellow to pale brown in colour with pink and yellow tints, and a coarse, interlocked grain.

Yellow Gum – a native Australian hardwood prized for its strength and durability, making it ideal for structural engineering applications.

Yellow Gum is a medium sized native Australian hardwood valued for its toughness and durability. It is the perfect choice for heavy construction.

Other Names: Blue Gum, White Ironbark, South Australian Blue Gum, Large Fruited Blue Gum, Water Gum

Overview
Properties
Description
Applications

Overview

Yellow Gum or Eucalyptus leucoxylon is a medium sized hardwood that grows to about twenty metres in height. It is difficult to describe Yellow Gum as a single tree type, as there are many different sub-species, each with its own appearance and habitat. In general, trees of this species are noted for their long flowering period and attractive bark, which is dark and fibrous at the base of the trunk. The remainder of the trunk is smooth, grey, mottled yellow or white and bluish-grey on the upper trunk and branches.

The overall species has a native range extending from southern NSW through central and western Victoria into most of South Australia, including Kangaroo Island. Yellow Gum is suited to most areas except the tropics and adapts to most soils. It is drought and frost tolerant, and moderately fast growing. It also tolerates smog.

Yellow Gum timbers are prized for their hardness, durability and impressive structural properties. Its vast range and availability make it an appealing choice for those requiring timber for heavy construction purposes. Common uses include heavy construction as posts, wharfage, bridgework, sleepers and fencing.

The timber is also termite resistant, although the sapwood is prone to lyctid borer. Workability is sacrificed for durability, as the timber is extremely dense and heavy. For this reason, it is not well suited to cabinetry.

Yellow Gum timber ranges in colour from yellow to pale brown. Grain is interlocked with a moderately coarse texture and often produces an attractive fiddleback figure.

Yellow Gum is often used in gardening as a screen, for windbreaks, and for displays of long-lasting, attractive flowers. It can be used to produce fine honey.

Properties

Shrinkage

	Very Low	Low	Medium	High	Very High
Tangential:
Tangential:	0.0
Radial:	0 - 2

Strength Group

	Very High	High	Reasonably High	Medium High	Medium	Reasonably Low	Low	Very Low
Unseasoned:	S1	S2	S3	S4	S5	S6	S7
Unseasoned:
Seasoned:	SD1	SD2	SD3	SD4	SD5	SD6	SD7	SD8
Seasoned:

Stress Grade

	Structural No. 1	Structural No. 2	Structural No. 3	Structural No. 4	Structural No. 5
Unseasoned:	F14	F11	F8	F7	F5
Seasoned:	F22	F17	F14	F11	F8

Density per Standard

Unseasoned:	1200 kg/m³
Seasoned:	1010 kg/m³

Joint Group

	Very High	High	Reasonably High	Medium	Low	Very Low
Unseasoned:	J1	J2	J3	J4	J5	J6
Unseasoned:
Seasoned:	JD1	JD2	JD3	JD4	JD5	JD6
Seasoned:

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:	87
Modulus of Rupture - Seasoned:	111
Modulus of Elasticity - Unseasoned:	11
Modulus of Elasticity - Seasoned:	12
Maximum Crushing Strength - Unseasoned:	44
Maximum Crushing Strength - Seasoned:	67
Impact - Unseasoned:	17
Impact - Seasoned:	8.5
Hardness - Unseasoned:	9.1
Hardness - Seasoned:	11

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
Termite Resistance:	Resistant

Fire Properties

	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
EFH Ignitibility:

	0	1	2	3	4	5	6	7	8	9	10
EFH Spread-of-Flame Index:
EFH Smoke-Developed Index:

Critical Radiance Flux - Lower:	>2.2 and <4.5 kW/m²
Critical Radiance Flux - Higher:	≥4.5 kW/m²
Smoke Development Rate:	<750

	1 - non-combustible	2 - reasonably non-combustible	3 - slightly combustible	4 - combustible
Fire Properties Group Number:

Average Specific Extinction Area:	<250
Bushfire Resistance:	BAL 12.5 and 19 – All AS3959 required applications

Description

Botanical Name:	Eucalyptus leucoxylon
Preferred Common Name:	Yellow Gum
Other Names:	Blue Gum, White Ironbark, South Australian Blue Gum, Large Fruited Blue Gum, Water Gum
Species Type:	Hardwood

Appearance

The heartwood of the Yellow Gum is, as its name suggests, yellow to pale brown in colour. It is common for the heartwood to exhibit pink and yellow tints around features. Sapwood is slightly paler and easily distinguished from the heartwood.

Due to the high density of this moderately fast growing timber, Yellow Gum features an interlocked grain and a somewhat coarse texture. It often produces an attractive fiddleback figure.

Common Applications

Yellow Gum timbers are prized for being hard, strong and very durable. This is an ideal timber for structural engineering purposes, including fencing and building. Timber of the Eucalyptus leucoxylon is used for sleepers and poles and is well suited to heavy construction such as wharfage and bridgework.

Yellow Gum timber is also ideal for use as fuel as it burns with few sparks and makes excellent coals. However, its density and hardness make it very difficult to split, and it is also tough to ignite.

Common Form

Sawn

Workability

Yellow Gum is a very heavy, durable timber. It has a high rating in all classifications. Timber of this species dries to about 1000kgs/m3 (66lbs/ft3). The in-ground durability of Yellow Gumtimber is class 2, as is its above ground durability. Yellow Gum heartwood is resistant to termites, but its sapwood is susceptible to lyctid borer.

When timbers are as hard and heavy as Yellow Gum, they are very hard to work. Cutter angles on planes need to be reduced. Pre-boring for fixings is considered mandatory. The timber can be glued, but it is best to do this immediately after dressing. It sands and polishes to a superb finish and accepts preservative impregnation.

Origin of Timber

VIC, SA

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