Hardwood Timber information (Spotted Gum)

(Corymbia maculata & Corymbia citriodora) Formerly E. maculata

Hardwood Timber Properties

Colour:
The heartwood ranges from light brown through to dark brown. Sapwood is usually white in colour and up to 50mm wide.

Grain:
Moderately coarse textured and variable. Gum veins common. The presence of wavy grain can produce an attractive fiddle back figure.

Hardness:
Very hard (rated 1 on a 6 class scale) in relation to resistance to indentation and ease of working with hand tools.

Machining:
Machines well due to its natural greasiness.

Finishing:
Will readily accept paint and polish. Has a lower tannin content than most other eucalyptus and is less likely to cause problematic tannin stains than most other Aussie hardwoods.

Hardwood Timber Uses

Engineering:
As sawn or round timbers in wharf and bridge construction, railway sleepers, crossarms, poles, piles, mining timbers.

Construction:
As unseasoned timber in general house framing and as seasoned dressed timber in cladding, internal and external flooring, lining and joinery. Also in fencing, landscaping, retaining walls and as structural plywood and hardboard.

Decorative:
Internal quality furniture, outdoor furniture, turnery, joinery, parquetry.

Others:
Tool handles, boat building, coach vehicle and carriage building, agricultural machinery, sporting goods (baseball bats, spring and diving boards, parallel bars), bent work. Spotted gum is the main Australian species for tool handles subject to high impact forces e.g. axe handles.

Its physical properties are well in excess of pines and most non Australian hardwoods. Tabled below is a comparison with Douglas fir and teak.

References:

1. Building Timbers - Technical Pamphlet No 1 - Queensland Forest Service 1991

2. Australian Standard 1720.1 Timber Structures Code 1988

3. Construction timbers in Queensland: Properties and specifications for satisfactory performance DPI & F.

4. Wood in Australia: Types, properties and uses.

Note:
When the strength and durability is the prime consideration and we may mix timber of similar or better properties which include ironbark, tallowwood, and forest red gum. This allows the best use of our species mix. When a uniform colour is required species are not mixed.

Sizes:
Australian hardwood is cut in multiples of 25 mm with the exception of 38 mm. The table below gives the sizes which can be expected in its different formats. For larger quantities we can cut to a fractional size.

Spotted Gum can be dressed into any profile you require within the table limitations below, e.g from a piece of 150 x 50 mm we can produce a seasoned sill with a maximum size of 136 x 42 mm.

*DAR - Dressed All Round

Notes:
Lengths (in multiple of 300 mm) to 4.8 metres are readily available and available up to 7.5 metres in limited quantities. Kiln drying is impractical over 50 mm thick. Larger sizes are frequently vertical laminated. Kiln dried timber is not required or recommended for bridge or boardwalk construction.

(The above information is largely drawn from Timber Queensland and NAFI publications.)