Timber iQ Dec 2017 - Jan 2018 // Issue:35 | Page 62

CONTRIBUTORS - WOOD WORKS The properties of Indian mahogany are summarised below for the wood enthusiast: INDIAN MAHOGANY: HARD FACTS Botanical/scientific name: Toona ciliate (Family: Meliaceae) Trade name: Indian mahogany Other names: Toon tree, Australian Toon (South Africa); red cedar (Australia); thitkado (Myanmar); youhom (Thailand); soeren (Indonesia); epi, kapere (Papua-New Guinea); Burma cedar (England). Origin: India, southeastern Asia and Australia (Queensland and New South Wales). Conservation status: The species is included in the IUCN Red List of Threatened Species and its status is ‘least concern’. In Australia the species was heavily and unsustainably exploited in the 19th and early 20th centuries, to the extent that today the availability of the species is low. In South Africa the species is a declared Category 3 invader. Bole characteristics: Indian mahogany is a large deciduous to evergreen tree, growing in its natural habitat to a height of 36m, with a clear bole of 24m and stem diameter of 1.5m. However, trees of this size are rare nowadays. In South Africa the average height attained is 10m, but trees of 35m have been recorded. Colour: The heartwood is reddish-brown to brick-red and strongly scented. The sapwood is pale brown and clearly demarcated. Grain pattern: The wood has a medium to coarse texture and a straight grain that is rarely interlocked. Distinct growth rings are visible on quarter sawn surfaces and it often produces attractive fiddleback – or ribbon figuring. Density (at 12% moisture content): 610kg/m 3 (540 to 670) (Ref. 7) 330-600kg/m 3 (Ref. 9) Strength/bending properties: The wood is moderately light and soft with low to medium strength properties. Seasoning: Air-drying: the wood dries quickly, but is somewhat refractory in drying characteristics, prone to warping, cupping and collapse. Proper spacing of stickers and weighting down of drying stacks is essential. Kiln drying: Schedule 2 is recommended (see below). Dry wood is stable in use. Durability and preservative treatment: The wood is moderately durable, but not suitable for exterior applications. It is moderately resistant to preservative treatment. Working and finishing properties: The wood saws, cuts and drills easily by hand or machine, with slight to moderate blunting of tools. Gum may accumulate on saw blades. It planes well to a smooth finish. The wood has good nailing, screwing and gluing properties and it takes all finishes well. It has good steam bending properties. TIMBER DRYING SCHEDULE FOR INDIAN MAHOGANY (Toona ciliate) 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. 2 Green 40% 30% 18% to final DB RH% DB RH% DB RH% DB RH% 45 74 50 67 55 58 65 34 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. REFERENCES AND SOURCES 1. Flynn, JH and Holder, CD (ed.) 2001. A Guide to Useful Woods of the World. Forest Products Society, Madison, WI. 2. Glen, H and van Wyk, B. 2016. Guide to Trees Introduced into Southern Africa. Struik Nature, Cape Town. 3. Otto, KP and van Vuuren, WFJ. 1977. The mechanical properties of timbers with particular reference to those grown in the Republic of South Africa. Bulletin 48. Department of Forestry, Pretoria. 4. Poynton, RJ. 1984. Characteristics and uses of selected trees and shrubs cultivated in South Africa. Bulletin 39, Directorate of