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Silver ash

Scientific name

Flindersia bourjotiana, F. schottiana. Family: Rutaceae

Other names

Queensland silver ash (F. bourjotiana only); northern silver ash; southern silver ash; cudgerie; bumpy ash

Description

  • Medium-sized tree, grows to 35m high.
  • Stem to 1m diameter.
  • Bole (trunk) is slim, usually well-formed and circular in cross-section.
  • Bark is about 15mm thick, fairly smooth or finely warted.
  • Usually recognised by swellings on the bole covering overgrown circles of broken-off limbs, giving it the local name of 'bumpy ash'.

Occurrence

Distributed mainly in the rainforest areas of northern New South Wales, and southern and northern Queensland:

  • F. bourjotiana—Mt Fox (southwest of Ingham) to Cooktown
  • F. schottiana—northern New South Wales to Gladstone; areas of the Atherton Tableland.

Appearance

Colour

  • Heartwood is silver-white to pale yellow.
  • Sapwood and heartwood show no colour difference.

Grain

  • Open and mostly straight.
  • Slight grain deviation may occur associated with bumps on the log surface.
  • Long straight vessel lines on longitudinal surfaces, but no obvious figure (pattern).

Uses

Decorative

  • Furniture, plywood, laminated beams.
  • Laminated bench tops, shop and office fixtures.
  • Flooring, lining, joinery, mouldings, parquetry flooring.
  • Turnery, carving, picture frames.

Others

  • Boat building, marine plywood, structural plywood.
  • Coach, vehicle and carriage building, aircraft construction.
  • Used, in the past, for tool handles (axe, adze, pick), scaffold planks, sporting goods (baseball bats, archery bows, billiard cues, cricket stumps, skis), bent work, draughtsperson´s implements, gun stocks, drum sticks, dowelling, fishing rods, boat oars, walking sticks, brush stock, broom handles.

Properties

  • Density: 640–675kg/m3 at 12% moisture content; about 1.5m3 of seasoned sawn timber per tonne.
  • Strength groups: S4 unseasoned, SD5 seasoned.
  • Stress grades: F7, F8, F11, F14 (unseasoned); F8, F11, F14, F17 (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: F. bourjotiana—5.5% (tangential), 3.0% (radial); F. shottiana—4.8% (tangential), 3.1% (radial).
  • Unit shrinkage: 0.29–0.31% (tangential), 0.20–0.21% (radial)—these values apply to timber reconditioned after seasoning
  • Durability above-ground: Class 3 (life expectancy 7–15 years).
  • Durability in-ground: Class 3 (life expectancy 5–15 years).
  • Lyctine susceptibility: untreated sapwood susceptible to lyctid borer attack.
  • Termite resistance: not resistant.
  • Preservation: sapwood readily impregnates with preservative, but penetration of heartwood is negligible using available commercial processes.
  • Seasoning: satisfactorily dries using conventional air and kiln seasoning.
  • Hardness: firm (rated 4 on a 6-class scale) to indent and work with hand tools.
  • Machining: machines, and turns well, to a smooth surface.
  • Fixing: no difficulty using standard fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts stain, polish and paint.

Identification features

General characteristics

  • Sapwood: creamy white to pale yellow, indistinct from the heartwood.
  • Heartwood: creamy white to pale yellow.
  • Texture: medium and uniform, without figure (pattern) but has sheen.

Wood structure

  • Growth rings: absent.
  • Vessels: medium to small, arranged in short radial multiples; may contain yellowish deposits; visible vessel lines on longitudinal surfaces.
  • Parenchyma (soft tissue): mostly in irregularly spaced, apotracheal bands.
  • Rays: visible without a lens.

Other features

  • Burning splinter test: match-size splinter burns to a full white ash.

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 edn, 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, Australian Standard International, Strathfield, NSW.