Timber iQ February - March 2018 // Issue: 36 | Page 56
CONTRIBUTORS - WOOD WORKS
The properties of sweet gum are summarised below for the wood enthusiast:
SWEET GUM: HARD FACTS
Botanical/scientific
name: Liquidambar styraciflua
(Family: Hamamelidaceae)
Trade name: Sweet gum
Other names: Liquidambar (South Africa); alligator tree, alligator wood, Liquidambar, redgum, sapgum,
star-leafed gum, bilsted (US); amberhout (The Netherlands); satin walnut, hazel pine (Great Britain)
Origin: US and central America
Conservation status: According to the IUCN Red List of Threatened Species, its status is ‘least concern’.
Bole characteristics: Sweet gum, in its natural habitat, grows to a height of 24 to 36m. A clear bole of about 17m long and
0.6 to 1.0m in diameter is commonly harvested. In South Africa, the tree usually grows to a height of
10m, although the maximum height recorded here is 30m.
Colour: The heartwood is brown, tinged with red, often with darker streaks and the sapwood is
creamy white.
Grain pattern: The grain is often interlocked, producing an attractive striped figuring. The wood has a uniform,
fine texture and satiny lustre.
Density (at 12%
moisture content): 560kg/m 3 (Ref. 1).
On average 630kg, but anything ranging from 580 to 740kg/m 3 (Ref. 5).
On average 560kg, but anything ranging from 490 to 620kg/m 3 (Ref. 6).
Strength/bending
properties: The wood is moderately strong and stiff with low to medium strength properties.
Seasoning: The wood can be satisfactorily air- or kiln-dried. Thin stock tends to warp and twist in the early
stages of drying, unless carefully stacked. After seasoning, the wood is dimensionally stable.
Kiln drying: schedule 1 is recommended (see below).
Durability and
preservative
treatment: The wood is moderately durable and permeable to preservative treatment.
Working and finishing The wood saws, cuts and drills easily by hand or machine, with only a slight blunting effect on
properties:
tools. It planes well to a smooth finish, despite the irregular grain often encountered. The wood has
good nailing, screwing and gluing properties and it takes all finishes well. Veneer can be readily
stained to simulate a range of other woods, such as cherry, maple or mahogany.
TIMBER DRYING SCHEDULE FOR SWEET GUM (Liquidambar styraciflua)
Supplied by H-P Stöhr, Timber Drying Institute ([email protected])
Dry Bulb temperatures (°C) and Relative Humidity (%) at the following Timber Moisture Contents
Drying schedule no.
1
Green
40%
30%
18% to final
DB 1RH% DB RH% DB RH% DB RH%
35 77 40 65 45 53 60 32
DB = Dry bulb temperature, RH = Relative Humidity
Please note: Drying schedules only serve as a guide to the kiln operator, with the response
of the timber to the drying condition being the criterion.
54 FEBRUARY / MARCH 2018 //