Coachwood
Scientific name
Ceratopetalum apetalum. Family: Cunoniaceae
Other names
Scented satinwood; tarwood
Description
- Medium-size hardwood.
- Grows straight with smooth, fragrant, greyish bark.
- Stem has distinctive horizontal marks, or scars, which often encircle the trunk.
- Larger trees have short buttresses.
Occurrence
- Occurs in the central and northern coastal rainforests of New South Wales and southern Queensland.
- Prefers gullies and creeks and often occurs in almost pure stands.
Appearance
Colour
- Heartwood is pale pink to pinkish brown.
- Sapwood not always distinguishable.
Grain
- Grain is usually straight.
- Texture is fine and even, often highly figured on the tangential face due to many bands of soft tissue.
Other
- Wood has a characteristic caramel odour.
Uses
- Construction: flooring.
- Decorative: furniture and cabinetwork, interior fittings, turnery, gun stocks, carving, veneer.
- Others: spars and masts in boat building.
Properties
- Density: 625kg/m3 at 12% moisture content; about 1.6m3 of seasoned, sawn timber per tonne.
- Strength groups: S5 unseasoned, SD4 seasoned.
- Stress grades: F5, F7, F8, F11 (unseasoned); F11, F14, F17, F22 (seasoned) when visually stress-graded according to AS 2082—2000, Timber—Hardwood—Visually stress-graded for structural purposes.
- Joint groups: J3 unseasoned, JD3 seasoned.
- Shrinkage to 12% MC: 8.1% (tangential), 4.0% (radial).
- Unit shrinkage: 0.34% (tangential), 0.24% (radial)—these values apply to timber reconditioned after seasoning.
- Durability above-ground: Class 4 (life expectancy less than 7 years).
- Durability in-ground: Class 4 (life expectancy less than 5 years).
- Lyctine susceptibility: untreated sapwood susceptible to lyctine borer attack.
- Termite resistance: not resistant.
- Preservation: sapwood readily impregnates with preservative, unlike the heartwood, where penetration is negligible using available commercial processes.
- Seasoning: seasons well, some risk of internal checking; collapse is slight, so reconditioning is unnecessary.
- Hardness: firm (rated 4 on a 6-class scale) to indent and work with hand tools.
- Machining: machines well to a smooth surface using hand or machine tools.
- Fixing: screws well, but tends to split when nailing; therefore, needs pre-drilling.
- Gluing: glues well.
- Finishing: readily accepts paint and polish; however, takes water and spirit stains better than oil stains.
Identification features
General characteristics
- Sapwood: pink-brown.
- Heartwood: light brown to pink-brown.
- Texture: fine and uniform, straight grained.
Wood structure
- Vessels: very small, visible only with lens; solitary, multiples and short radial chains.
- Parenchyma (soft tissue): plentiful in irregularly spaced, apotracheal bands, distinct without lens.
- Rays: fine, visible with a lens.
Other features
- Burning splinter test: match-size splinter burns to a partial white or grey ash.
- Figure: prominent on the back-sawn surfaces (tangential) due to bands of parenchyma.
- Odour: obvious and characteristic, similar to caramel.
Research and resources
- Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, Forest trees of Australia, 5th ed., CSIRO Publishing, Collingwood Australia.
- Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.
- Ilic, J 1991, CSIRO atlas of hardwoods, Crawford House Press, Bathurst, Australia.
- Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
- Standards Australia, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.
- Last reviewed: 12 Dec 2018
- Last updated: 12 Dec 2018