Timber iQ August - September 2017 // Issue: 33 | Page 54

CONTRIBUTORS - WOOD WORKS Continued from page 50 Here is some additional information on the properties of Saligna for the wood enthusiast: SALIGNA: HARD FACTS Botanical/scientific name: Eucalyptus grandis Hill. Ex Maid. (Family: Myrtaceae) Trade name: Saligna, Saligna Gum, Grandis Gum, Rose Gum, Flooded Gum Origin: The tree occurs naturally along the eastern coast of Australia, from Newcastle on the central coast of New South Wales to Bundaberg in southern Queensland. Smaller stands are found on the central Queensland coast and in northern Queensland. Conservation status: The species is not threatened in its natural habitat and is not listed in the CITES Appendices or on the IUCN Red List of Threatened Species. In South Africa, particularly in KwaZulu-Natal, Mpumalanga and Limpopo provinces, it is declared a Category 1b invader as it competes with, and replaces, indigenous species and stands of trees along watercourses may reduce stream flow. Bole characteristics: Trees grow fast and reach heights of between 30 and 55m with stem diameters of 1.0 to 2.5m. Colour: The heartwood ranges from pink to reddish-brown and the sapwood is lighter in or greyish and not always easily distinguished. It has no characteristic odour. Grain pattern: The grain is straight to slightly interlocked and the texture of the wood is medium to coarse and even. Density (at 12% moisture content): 570 (500-800)kg/m 3 at 12% mc (Ref. 3) 600-840kg/m 3 at 12% mc (Ref. 5) Strength/bending properties: The wood displays medium to high bending strength and bending stiffness and high crushing strength. Shearing strength and side grain hardness is classified as medium. Seasoning: The wood is difficult to dry. Radial shrinkage is small to moderate and tangential shrinkage is moderate to fairly large during drying. It tends to develop moderate cupping and surface checking. Splitting, spring, knots, kino-veins, brittleheart and wild grain may also be encountered. Kiln drying schedule 1 is recommended (see below). Once dry, the wood displays medium movement in use. Durability and preservative treatment: The wood is classified as non-durable to moderately durable. The heartwood is resistant to preservative treatment and the sapwood is permeable to moderately resistant. Working and finishing properties: The wood saws moderately easy and cleanly. Logs containing growth stresses are difficult to saw accurately on any but a frame saw. The wood has easy to moderate machining properties. It planes to a smooth surface and turning, recessing and routing properties are moderate. The wood nails well, but has poor resistance to splitting in nailing and screwing. It has good gluing and polishing properties and can be stained successfully to resemble mahogany. Generally, the finishing properties are satisfactory. TIMBER DRYING SCHEDULE FOR LIGHT SALIGNA GUM (Eucalyptus grandis) 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 RH% 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. 52 AUGUST / SEPTEMBER 2017 //