Gum, Manna

Manna gum is a hardwood timber species occurring in the cooler areas of South Australia, Tasmania, Victoria and the tableland districts of New South Wales. The heartwood of the species is a pale pink or pinkish-brown colour, often with distinctive light grey streaks. Sapwood is not clearly distinguishable from the true wood. The texture of manna gum timber is medium and even with a variable grain and prominent growth rings. It is usually quarter-sawn.

Manna gum is a moderately durable timber. Its heartwood lacks natural termite resistance and untreated sapwood is susceptible to lyctid borer attack. Although moderately hard, manna gum timber is easy to work by hand or machine. It glues satisfactorily using commercially available bonding agents. Pre-drilling is recommended when nailing near the ends of boards, to avoid splitting.

Uses of manna gum timber range from general construction to internal joinery, furniture, paneling, flooring and tool handles. Potential applications include plywood.

Despite a striking appearance especially suited to more formal decorative applications, manna gum timber is relatively uncommon due to the difficulties it presents in drying. The timber is prone to internal honeycombing, surface checking and collapse during seasoning.

Appearance

Manna gum heartwood is a pale pink or pinkish brown colour, often with distinctive light grey streaks. Sapwood is not clearly distinguishable from the true wood. The texture of manna gum timber is medium and even, with a variable grain and prominent growth rings. It is usually quarter sawn.

Common Applications

Uses of manna gum timber range from general construction to internal joinery, furniture, panelling, flooring and tool handles. Potential applications include plywood.

Despite a striking appearance especially suited to more formal decorative applications, manna gum timber is relatively uncommon due to the difficulties it presents in drying.

Workability

Although moderately hard, manna gum timber is easy to work. It glues satisfactorily using commercially available bonding agents. Pre-drilling is recommended when nailing near the ends of boards, to avoid splitting.

During seasoning, the timber is prone to degradation in the form of internal honeycombing, surface checking and collapse.

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Although a common eucalypt, manna gum is of limited commercial availability because of seasoning problems.

Availability - Further Information

Native Forest

Shrinkage

Very Low Low Medium High Very High

Tangential :

12.00%

Radial:

5.10%

Unit Movement Tangential:

0.34%

Unit Movement Radial:

0.22%

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

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:

F14

F11

F8

F7

F5

Seasoned:

F22

F17

F14

F11

F8

Density per Standard

Seasoned:

780kg/m3

Unseasoned:

1000kg/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:

66

Modulus of Rupture - Seasoned:

106

Modulus of Elasticity - Unseasoned:

11

Modulus of Elasticity - Seasoned:

15

Maximum Crushing Strength - Unseasoned:

32

Maximum Crushing Strength - Seasoned:

62

Impact - Unseasoned:

15

Impact - Seasoned:

15

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

5.1

Hardness - Seasoned:

5.8

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:

Not Resistant

Fire Properties

Critical Radiance Flux - Lower:

>2.2 and <4.5

Critical Radiance Flux - Higher:

>2.2 and <4.5

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

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