Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 1 Feature Article Development of a Timber Property Classification Based on the End-Use with Reference to Twenty Sri Lankan Timber Species N.D. Ruwanpathirana State Timber Corporation, Sri Lanka Abstract An investigation was carried out on selected 20 timber species of Sri Lanka to study different wood properties, i.e., wood density, modulus of rapture, modulus of elasticity, compression parallel to grain, shrinkage/movement, workability (sawing, nailing, sanding and finishing), treatability of preservative, timber durability, timber texture by vessel diameter and some gross properties, timber colour and present timber uses. Based on the results, an attempt was made to classify the studied timber species into property levels. The final objective of this study was to develop relationships between the end-uses of timber and their property requirements and levels with reference to 20 Sri Lankan timber species. Timber selection for the use in Sri Lanka is species-oriented and sometimes it is based on the traditional use. Based on wood properties of 20 Sri Lankan timber species selected, an attempt was made to recognise the most important wood properties and their levels to develop a four end-use property classification. In general, the proposed end-use property classification in this study could be differentiated as (i.) for building construction, (ii.) for furniture and joinery (iii.) for light construction, and (iv.) for miscellaneous uses. Among the selected timber species, Dipterocarpus zeylanicus is eminently suitable for under-water work. Eucalyptus microcorys is regarded as one of the best timbers for dancing floors. These specialty and causative factors of timber, however, must be explored and documented in order to prepare end-use property classification for miscellaneous use. 1. Introduction Sri Lanka a small island of 6,561,000 ha, posses a significant biodiversity along with various tree species. Total natural forest cover in Sri Lanka is 1,951,472 ha which consists 1,521,987 ha of closed canopy forests and 429,485 ha of open canopy forests. There are over 350 timber tree species present in these forests and other crown lands. Present annual timber consumption in Sri Lanka is 1.6 million m 3 from which around 10% is supplied by imports. Forest plantations and homegardens that have the potential of producing good quality timber, contribute about 10% and 40% of national timber requirements respectively. * Correspondence: nimalruwan@gmail.com Tel: +94 112885853 ISSN 2235-9370 Print/ISSN 2235-9362 Online © University of Sri Jayewardenepura Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 2 Wood properties vary with timber species and each and every property may bring a unique value and important feature to timber and its end-use. This variability of timber serves a variety of uses and if a particular timber is good for one purpose it may not be useful for another purpose. In general, selection of timber species for particular end-use depends on technical performance of timber such as durability, movement, strength, stiffness and toughness, permeability and ease of processing. Lack of knowledge on mechanical properties of structural timber leads to structural application of unnecessarily high safety margins in timber design. As far as wood properties of Sri Lankan timber species are concerned, comprehensive studies were not conducted on physical properties, mechanical properties, anatomical properties, gross features, working properties, durability, timber seasoning and preservation. Timber selection for the use is species oriented, sometimes on the basis of traditional use, however, more frequently on considerations of availability, cost, size and performance. Therefore information is much useful for the selection of timber species for the end-use because an appropriate combination such technical information is often among the last to be considered at present. An end-use property classification can be defined in the first place for building construction, furniture and joinery, light construction work and miscellaneous uses, flooring and furniture. For instance, property requirements and preferable property level for property classification for major user groups can be judged based on experience of the factors which affecting performance, and guided by standards and specifications. This paper provides most of important wood properties with its property levels such as density, some mechanical properties, natural durability and treatability, dimensional movement and seasoning properties, working properties, gross features (colour and texture). Hence using this information on property requirements for a product, it is possible to select the suitable timber species in which required technical information is available. The objectives of the present study were to determine wood properties of 20 selected Sri Lankan timber species (Table 1), to classify the studied wood properties into property levels and to develop relationships between the end-uses of timber and their property requirement and levels with reference to twenty Sri Lankan timber species. Table 1: List of commonly used timber species. No Name Scientific name Family 1 Acacia Acacia malanoxylon Fabaceae 2 Ginisapu Michelia champaca Magnoliaceae 3 Grandis Eucalyptus grandis Myrtaceae 4 Havarinuga Alstonia macrophylla Apocynaceae 5 Hora Dipterocarpus zeylanicus Dipterocarpaceae 6 Ketakala Bridelia retusa Phyllanthaceae 7 Khaya Khaya senegalensis Meliaceae 8 Kohomba Azadirachta indica Meliaceae 9 Kolon Adina cordifolia Rubiaceae 10 Kos Artocarpus heterophyllus Moraceae 11 Kumbuk Terminalia arjuna Combretaceae Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 3 12 Liyan Homalium zeylanicum Salicaceae 13 Lunumidella Melia dubia Meliaceae 14 Mahogany Swietenia macrophylla Fabaceae 15 Mee Madhuca longifolia Sapotaceae 16 Microcorys Eucalyptus microcorys Myrtaceae 17 Para Mara Albizia saman Fabaceae 18 Rubber Hevea brasiliensis Euphorbiaceae 19 Teak Tectona grandis Verbenaceae 20 Toona Toona ciliata Fabaceae 2. Materials and Methods Authentic timber samples of 20 Sri Lankan timber species were collected from the Research Division of State Timber Corporation (STC) along with fresh wood samples from the mature trees in the field. Wood samples and disks were cut from each species at breast height of the tree. The collected specimens from the two sources mentioned above were compared anatomically with each other for the confirmation of species identity. A radial strip was cut from each disk for the investigation of anatomical characteristics. Required number of timber samples with necessary dimensions were cut and removed for the measurement of specific gravity, mechanical properties, shrinkage and movement, durability testing at grave yard, boron preservation, working properties, wood texture and heartwood colour. 2.1 Timber density A radial strip cut from each disk was used for the measurement of timber density. Timber density was determined on the basis of oven-dry weight and green volume. Timber density of 20 species studied were grouped into four categories as light wood (<= 500 kgm -3 at 12% moisture content), medium density wood (500-640 kgm -3 ), high density wood (640-840 kgm -3 ) and very high density wood (>840 kgm -3 ). 2.2 Shrinkage and movement Wood specimens (2×2 cm in cross section and 5 cm long) in green state were weighed up to the accuracy of 0.001 g and conditioned to achieve constant weights at about 10-12% moisture and then oven-dried at 103 0 C until a constant weight was obtained. Lengths of the specimens along radial and tangential plane at green, air dry and oven dry conditions were measured and radial and tangential shrinkages were calculated. These samples, prior to use for oven dry measurement were subjected to determine the timber movement under atmospheric condition from relative humidity of 80% to relative humidity of 60%. Shrinkage and movement properties levels were categorised into three groups as high (>12%), medium (7%-12%) and low (<7%). 2.3 Mechanical properties Static bending test of air-dried 2×2 cm (cross section) and 30 cm long specimen was carried out using a universal test machine. Deflections and the corresponding loads were recorded and load deflection curves were prepared. Modulus of rapture and modulus of elasticity were Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 4 calculated. Compression perpendicular to grain was also carried out by same machine using timber sample of 2×2 cm (cross section) and 6.2 cm long specimen. 2.4 Wood durability. Heartwood timber samples (5×5×60 cm) were buried in ground following the principle of grave yard experiment and deterioration of timber with time table were observed. Timber durability was classified as non-durable (<5 years), moderately durable (5-10 years) and durable (>10 years). In addition, ground survey was conducted to collect information of timber durability. 2.5 Timber treatability with boron preservation Depth of penetration and retention of boron preservative were calculated after timber samples were immersed in the boron solution complying for standard procedure. Boron retention levels were classified as easy (>10 kgm -3 ), medium (6-10 kgm -3 ) and difficult (<6 kgm -3 ). 2.6 Wood colour Wood samples containing both heartwood and sapwood were used to determine wood colour according to IAWA (1989) category No. 197 to 202 by naked eye. Heartwood colour was categorised mainly into four groups, namely, (i.) basically brown or shade of brown, (ii.) red or shade of red, (iii.) yellow or shade of yellow and (iv.) white to grey. Visible differentiation of heartwood color from sapwood was also studied. 2.7 Anatomical characteristics A radial strip taken from the pith to bark was used for the investigation of anatomical characteristics. These wood samples were boiled in water for about two hours to soften them. Each wood sample was shaped and sized into wood block of 2×2×3 cm. Transverse, radial and tangential sections at the range of 10-15 µm thickness were obtained by using a sledge microtome (Model Leica SM2000 R). The permanent slides of wood were prepared after dehydrated and stained in safranin. Sections were mounted using Canada balsam using standard procedure. Microscopic observations of each slide were made for qualitative and quantitative analysis of parameters under the light microscope at 4×10 magnifications. Measurements on wood anatomical features were taken after photomicrographs of each slide were made by Olympus microscope and Micromertics SE Premium 4 software available in the Research Division of STC. Measurements of tangential vessel diameter were used to determine the wood texture. 2.8 Wood texture Mean vessel tangential diameter, ray width and ray height were measured in this study from which average tangential diameter of the vessel (µm) was used to determine wood texture. Vessel size is primarily responsible for texture, however, in a wood with large rays and vessels of moderate size or small size, coarse texture may ensure from large rays alone. The classification given in Table 2 and ray information studied serve to indicate roughly the basis of classification. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 5 Table 2: Classification of wood texture. Type of wood texture Average tangential diameter of the vessel (µm ) Fine textured Less than 100 microns Medium textured 100 to 200 microns Coarse textured More than 200 microns 2.9 Wood working properties Wood working properties such as sawing, nailing, sanding and polishing were determined with the assistance of an experienced carpenter. Accuracy of the results was maintained by doing repeated tests. In order to obtain an idea of sawing ability, air seasoned, uniform thickened mature heartwood potions were also tested by the experienced carpenters. In order to depict data clearly, results were grouped into three categories as easy, moderate and difficult. For nailing, the air seasoned mature heartwood samples in dimensions of 132×7.5×12 mm were used. The nailing was done on cross section surface 13 mm interior to the border. Results were categorised into three groups as easy, moderate and difficult. Sanding data were obtained through number 320 sanding paper and results were categorized as very good, good and moderate. Final finishing property also classified as very good, good and moderate. 2.10 Islandwide survey An Islandwide questionnaire survey was conducted to gather information from timber users who have experience on timber durability particularly using timber in outdoor uses. 3. Results Table 3, 4, 5, and 6 present in the following sections illustrate all wood properties studied in this research work. Table 3: Wood density and density property classes, modulus of elasticity, modulus of rupture and compression parallel to grain of the selected timber species. No Species Density class Density At 12% m.c. Modulus of elasticity (Nmm -2 ) Modulus of rupture (Nmm -2 ) Compression parallel to grain (Nmm -2 ) 1 Acacia malanoxylon HD 738 11,811 90 45 2 Michelia champaca LD 500 8,503 64 32 3 Eucalyptus grandis MD 595 9,827 74 37 4 Alstonia macrophylla HD 690 11,150 84 43 5 Dipterocarpus zeylanicus HD 762 12,142 92 47 6 Bridelia retusa VHD 850 13,500 103 50 7 Khaya senegalensis MD 603 9,932 75 37 8 Azadirachta indica HD 714 11,481 87 44 9 Adina cordifolia HD 666 10,819 82 41 10 Artocarpus heterophyllus MD 625 10,250 78 39 Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 6 11 Terminalia arjuna HD 714 11,481 87 44 12 Homalium zeylanicum HD 738 11,811 90 45 13 Melia dubia LD 400 6,050 40 20 14 Swietenia macrophylla MD 609 10,025 76 38 15 Madhuca longifolia VHD 900 14,250 115 58 16 Eucalyptus microcorys VHD 875 13,719 105 53 17 Albizia saman MD 585 9,694 73 36 18 Hevea brasiliensis MD 540 9,059 68 34 19 Tectona grandis HD 720 11,550 88 43 20 Toona ciliata LD 500 850 60 30 * LD = Low density, MD = Medium density, HD = High density, VHD = Very high density. Table 4: Wood working properties, seasoning and wood shrinkage in twenty timber trees. No Scientific name Seasoning & shrinkage Working properties 1 Acacia malanoxylon Must be thoroughly seasoned. Seasons well. Shrinkage green to oven dry is 6%. Easy to work with hand and machine tools. Excellent polishing properties. Glues & stains well. Poor nailing. Splits easily & pre- boring is recommended. 2 Michelia champaca Seasoning is not easy as the timber is liable to split especially if left in the log form. Shrinkage green to oven dry is 8.4%. Easy to saw & works to a smooth surface. Good polishing. 3 Eucalyptus grandis Difficult to season, Cupping may occur in back-sawn boards, but can be removed by reconditioning treatment. Shrinkage green to 10% moisture content is 6.03%. Young trees work easily. Old material may produce certain surface wooliness & tendency to split. Free from defects. Good polishing. Tends to split in nailing. 4 Alstonia macrophylla Green conversion & immediate seasoning give best results. Shrinkage green to 10% moisture content 8.92%. Sawing & nailing are somewhat difficult. Easy to sanding & takes a good polish. 5 Dipterocarpus zeylanicus Seasoning is somewhat difficult. Air drying is needed before kiln drying. Shrinkage green to 10% moisture content is 6.63%. Easy to sawing. Somewhat easy to nailing. Easy to sanding & finishing is somewhat good. 6 Bridelia retusa Seasons defects sometimes appear & hence green conversion & prompt stacking for slow drying is recommended. Shrinkage green to 10% moisture content is 5.45%. Saws and machines well & works to a smooth surface. Easily worked with hand tools. 7 Khaya senegalensis Seasons well. Shrinkage green to 10% moisture content 4.78%. Easy to sawing, nailing & sand papering. Good finish when polished. Filling materials should be used. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 7 8 Azadirachta indica Seasons well. Shrinkage green to 10% moisture content is 2.48%. Somewhat difficult to sawing. Easy to nailing & sand papering. Poor finish when polishing (good for staining). 9 Adina cordifolia Seasons well. Shrinkage green to oven dry is 10.2%. Shrinkage green to 10% moisture content is 5.88%. Easy to sawing & sand papering, slightly difficult to nailing, good finish after polishing. 10 Artocarpus heterophyllus Seasons easily. Shrinkage green to 10% moisture content is 1.62%. Easy to saw & work. Finish well particularly if fillers & sealers are used. Polish with a high lustre. 11 Terminalia arjuna Seasons well. Should dry slowly. Large timber prone to crack split & bend. Shrinkage green to 10% moisture content is 5.79%. Difficult to sawing & nailing. Sand papering is easy. Good finish when polishing. 12 Homalium zeylanicum Somewhat difficult to seasons. Shrinkage green to 10% moisture content 14.4%. Saws and works easily. Takes a good polish. 13 Melia dubia Seasons easily. Shrinkage green to 10% moisture content is 6.06%. Easy to saw & work, but difficult to obtain a smooth finish on the account of its softness. 14 Swietenia macrophylla Seasons well & easily without much checking or distortion. Kiln drying satisfactorily when moderate scheduling. Shrinkage green to 10% moisture content is 2.93%. Saws, planes & moulds easily, finish to a smooth surface. Wood takes an excellent polish. Gluing & nailing are good. Discolorations in contact with iron, copper & brass. 15 Madhuca longifolia Seasons well. If converted green, log tend to split at the ends if left unconverted. Shrinkage green to 10% moisture content is 8.65%. Sawing is somewhat easy. Difficult to nailing & easy for sand papering. Good finish when polished. 16 Eucalyptus microcorys Somewhat difficult especially with fast grown timber. Shrinkage green to 10% moisture content is 9.77%. Easy to saw. Difficult to nail, sanding & polishing. Difficult to obtain a good polish. 17 Albizia saman Seasons well. Shrinkage green to 10% moisture content is 9.18%. Easy to sawing, nailing & sand papering. 18 Hevea brasiliensis Seasons well. Shrinkage green to 10% moisture content 7.69%. Easy to sawing, nailing & sand papering. Good finish when polishing. 19 Tectona grandis Once seasoned "movements" are very little. Shrinkage green to oven dry is 9.9%. Not difficult to saw or work, but care is need in working as the timber is somewhat brittle. 20 Toona ciliata Seasons easily but radial checks & heart-shakes develop in the log. Careful stacking is required to prevent warping. Shrinkage green to 10% moisture content is 9.85%. Saws & works easily with good finishing qualities. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 8 Table 5: Durability of wood , wood texture and heartwood colour. No Scientific name Durability Heart wood colour and wood texture 1 Acacia malanoxylon Durable. Resistant to effective preservative treatments. Brown or shaded of brown (IAWA). Rich reddish brown to nearly black banded with golden brown or red. Even, medium to even textured. 2 Michelia champaca Durable. Easy to medium ability to apply preservative treatments. Yellow or shaded of yellow (IAWA). Light yellowish brown to olive brown. Lustrous. Even & medium textured. 3 Eucalyptus grandis Moderately durable. Somewhat difficult to apply preservative treatments. Red or shaded of red (IAWA). White to pink or light to dark red brown with a pink tinge, depending on age and area of origin. Medium or coarse textured. 4 Alstonia macrophylla Moderately durable. Easy to apply preservative treatments. Yellow or shaded of yellow (IAWA). No distinct heartwood. Cream colour. Medium, even textured. 5 Dipterocarpus zeylanicus Moderately durable. Somewhat difficult to apply preservatives. Red or shaded of red (IAWA). Light pinkish brown on first exposure ageing to reddish brown. Even & coarse textured. 6 Bridelia retusa Durable. Difficult to apply preservative treatments. Brown to shaded of brown (IAWA). Dark to olive brown sometimes with darker streaks. Medium & fairly even textured. 7 Khaya senegalensis Moderately durable. Easy to apply preservative treatments. Red or shaded of red (IAWA). Even pink colour to reddish brown (mahogany brown). Medium & coarse textured. 8 Azadirachta indica Durable. Difficult to apply preservative treatments to heartwood. Red or shaded of red (IAWA). Red when first exposed darkening to reddish brown & then resembling mahogany. Medium to somewhat coarse textured. 9 Adina cordifolia Moderately durable. Easy to apply preservative treatments. Yellow or shaded of yellow (IAWA). Citron yellow when first exposed, turning pale yellowish or reddish brown with age. Fine and even textured. 10 Artocarpus heterophyllus Durable. Resistant to effective preservative treatments. Yellow or shaded of yellow (IAWA). Yellow or lemon yellow gradually turning to a rich mahogany brown, very old wood to a warm Vandyke brown. Coarse textured. 11 Terminalia arjuna Durable. Easy to apply preservative treatments. Brown to shaded of brown (IAWA). Olive brown streaked with dark blackish lines. Coarse and even textured. 12 Homalium zeylanicum Durable. Difficult to apply preservative treatments. Brown to shaded of brown (IAWA). Yellowish brown to yellowish red on first exposure. Even & fine textured. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 9 13 Melia dubia Non-Durable. Easy to apply preservative treatments. Red or shaded of red (IAWA). Light pink to light red, when first exposed ageing to reddish brown. Coarse & somewhat uneven textured. Subject to a grey stain. 14 Swietenia macrophylla Durable. Resistant to effective preservative treatments. Red or shaded of red (IAWA). Reddish, pinkish, salmon coloured or yellowish when fresh, darkening to deep red or brown with age. Moderately fine to rather coarse. 15 Madhuca longifolia Durable. Difficult to apply preservative treatments. Red or shaded of red (IAWA). Dull, dark red, ageing to dull reddish brown streaked with light brown lines. Coarse & even textured. 16 Eucalyptus microcorys Durable. Resistant to effective preservative treatments. Yellow or shaded of yellow (IAWA). Pale or yellowish brown or straw colour. Moderately coarse & even textured. 17 Albizia saman Moderately durable. Resistant to effective preservative treatments. Brown to shaded of brown (IAWA). Golden brown to dark brown. Coarse textured. 18 Hevea brasiliensis Non-Durable. Easy to apply preservative treatments. Brown to shaded of brown (IAWA). Difficult to distinct from the softwood. White colour when first exposed, turn into pale brown when ageing. Pink tinge present. Coarse and even textured. 19 Tectona grandis Durable. Difficult to apply preservative treatments. Brown to shaded of brown (IAWA). Golden brown which darkens with age. Coarse and uneven textured. 20 Toona ciliata Moderately durable. Difficult to apply preservative treatments. Red or shaded of red (IAWA). Light brick red when first exposed, ageing to a rich reddish brown. Moderately fine & somewhat uneven textured. Table 6: Uses twenty timber species. No Scientific Name Uses 1 Acacia malanoxylon Furniture, boats, cabinets, plywood, doors & window frames, fittings in banks, railway carriages, gun stocks, decorative works. 2 Michelia champaca Reapers, ceiling spacers, door & window sashes, partition frames, floor boards, buildings, cheap furniture, valance boards. 3 Eucalyptus Grandis General construction, bridges, poles, posts, furniture, paneling, sleepers. 4 Alstonia macrophylla General construction, toys, match-boxes, posts, cheap furniture, coffins, carving, blackboards, transmission poles. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 10 5 Dipterocarpus zeylanicus Reapers, ceiling spacers, fascia boards, door frames, partition frames, cheap furniture, treated sleepers, transmission poles, construction, under- water work, piles, boards, scaffoldings, rafters, beams. 6 Bridelia retusa Rafters, purlins, ridge hips, ceiling joists, wall plates, beams, reapers, buildings, furniture, agriculture implements, drums, carts, cart shaft. 7 Khaya senegalensis Boxes, posts, light construction, ceiling boards, door & window sashes. 8 Azadirachta indica Furniture, paneling & decorative work, rafters purlins, ridges hips, ceiling joists, wall plates, reapers, buildings, panels, carvings, bottom of drawers. 9 Adina cordifolia General utility timber, purlins, ridge hips, reapers, railing spacers, door &window sashes, furniture, carvings, fine turnery wood, ornamental caskets, picture frames, brush-backs. 10 Artocarpus heterophyllus House building, furniture, carriages, cabinet making, musical instruments, boats, building, casks. 11 Terminalia arjuna Beams, rafters, purlins, ridge hips, ceiling joists, wall plates, furniture, construction, bridges. 12 Homalium zeylanicum Beams, rafters purlins, ridges hips, ceiling joists, wall plates, flooring, buildings, boats, oars, stair cases, brush backs, posts. 13 Melia dubia Ceiling boards, paneling & packing cases, cigar boxes. 14 Swietenia macrophylla Door &window frames, partition frames, furniture, cabinets, paneling & decorative work, railway carriages, piano cases, veneers. 15 Madhuca longifolia Heavy construction, agricultural implement, reapers, ceiling spacers, door &window frames, partition frames, heavy construction, posts, beams, boats, bridges. 16 Eucalyptus microcorys Piles, poles, posts, flooring, sleepers, transmission poles, heavy construction work, excellent for dance floors. 17 Albizia saman Beams, rafters, purlins, ridges hips, ceiling joists, wall plates, furniture, paneling, flooring. 18 Hevea brasiliensis Partition frames, ceiling boards, furniture, light construction, brush handles. 19 Tectona grandis Ship building, high class joinery, flooring, interior fittings, door & windows frame & sashes, stair cases, fancy goods, veneers, railway carriers, beams, rafters purlins, ridges hips, ceiling joists, wall plates, reapers, ceiling spacers, furniture, railway carriages. 20 Toona ciliata Furniture, paneling, cigar boxes, racing boats, musical instruments. 4. Discussion It can be understood that when popular or well known timber is not available or not affordable due to high cost, another timber species is sought often on the basis of comparability with that formerly used. In this timber selection process, the cost involved is often considerable and users may be reluctant to face risk accepting the unknown timber species. This situation can be altered by providing guidance on property needs for the appropriate to end-use. The end-use property classification given in this paper provides the means to make an objective assessment of the suitability for a particular purpose of timber use. However, this suitability of timber depends on the combined cost of the selected timber and additional cost involved for processing (e.g. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 11 preservation). This cost is compared with the cost of a timber which is not required for additional processing. Thelandersson & Hansson (1999) stated that wood has significant variations in its properties both between and within timber elements. Variations in strength properties may be species-specific, age-dependent and environmentally responsive. Therefore it is suggested to conduct more research work in this field based on more timber samples representing of the entire population. Understanding physical properties, mechanical properties, durability and gross features of various timber species are very much important in selecting timbers for various purposes. Correct use of timber always increases the life time of the final product, whether it is high class furniture or a simple craft work. This paper provides most important wood properties facilitating to select timber species according to end-use or end use requirement of twenty Sri Lankan timber species. In general, the proposed property classification in this paper can be categorised as (i.) end-use property classification for building construction, (ii.) end-use property classification for furniture and joinery (iii.) end-use property classification for light construction and (iv.) end-use property classification for miscellaneous uses. It is an imperative exercise to find out the most influential wood properties for each category of end use property classification given here with. Very high density timber such as Madhuca longifolia and Eucalyptus microcorys, studied in this research work are often chosen for heavy construction work due to not only its high strength property but also good performance experience in use for centuries. It was found that timber density of M. longifolia and E. microcorys are 900 kgm -3 and 875 kgm -3 at 12% m.c respectively. In addition, both species showed high values of mechanical properties such as modulus elasticity, modulus of rapture and compression parallel to grain (Table 3). Both timber species demonstrated effective resistant to boron treatment when application of preservatives was done. Furthermore, results of grave yard test showed that both timber species can be classified as durable timber. As far as wood working properties are concerned, sawing is easy and nailing is difficult for both species. Working properties like sanding and polishing did not demonstrate such similarity in M. longifolia and E. microcorys. These finding might be used to define the standard for quality requirement and quality level for end-use property classification for construction timber. In this classification, some important quality requirements like seasoning defects, dimensional movement etc. can also be included for further improvement. Further it is recommended that preferable property level of timber for major end-uses should be studied in future research. End-use property classification for furniture and joinery category which involves end-use products like window joinery, door and window frames, flooring and cabinet work etc. can be derived for the construction timber category mentioned in the earlier section. Acacia malanoxylon, Adina cordifolia, Artocarpus heterophyllus, Terminalia arjuna, Swietenia macrophylla, Tectona grandis and Eucalyptus grandis have proven timber quality complying with technical requirements, needed for end-use category of furniture and joinery. When variations of timber density of furniture and joinery category were analysed it was found that all the species can be categorised as medium to high density. This group of timber has somewhat lower density than to construction timber category. Results in Table 4 show that the timber in this category seasons well and demonstrated comparatively better working properties than those in Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 12 the construction category. According to IAWA (1989) classification, the heartwood colour of furniture category timber consists of different wood colour. A. malanoxylon, T. arjuna and T. grandis have brown or shaded brown colour and S. macrophylla and E. grandis have red or shaded red colour followed by A. cordifolia and A. heterophyllus with yellow and shaded yellow. According to this finding, property requirements and level for the end-use classification for furniture and joinery might be derived from these research findings and further development can be made with increased number of timber species. In this direction, we have initiated a research program to collect wood properties of 235 Sri Lankan timbers. The publication of “Sri Lankan timber: Timber properties and its uses” covering 100 timber species is now in the press and it will be helpful to those who are willing to continue research in this regard. Among many timber varieties used for light construction work in Sri Lanka, M. champaca, M. dubia , T. ciliate and H. brasiliensis are the most popular timber species. It can be assumed that wood properties in this study might influence mainly for the end-use application. Therefore by recognising these influential wood properties, it was possible to list out major property requirements and level for end-use property classification. According to Table 3, all the above timber species belong to light to medium density categories and having low mechanical properties. Both H. brasiliensis and M. dubia are non-durable and both timber can be preserved easily. According to the results of the boron treatment (Table 5), M. champaca and T. ciliate were classified as easy/medium category and difficult category respectively. All three species which were tested for working properties showed almost similar results indicating that working properties such as sawing and nailing are easy. Major property requirements for end-use property classification for light construction can be identified by these results. End-use property classification for miscellaneous uses might be developed for the specific end-use application. For instance, M. longifolia timber is perfect for storing boxes of paddy seeds or container because this timber is capable to repulse pests or insects that use to come and destroy the paddy yield. Some timber species such as B. cordifolia is highly demanded for manufacturing of vats. It is believed that B. cordifolia timber can enhance the quality of liquor by absorbing unfavorable matters and improve the taste and smell. Timber like B. retusa and V. pinnata possess special wood quality which helps to persist the timber in ground contact environment without getting deterioration. D. zeylanicus is eminently suitable for under-water work. E. microcorys is regarded as one of the best timber for dance floors. This specialty and causative factors of timber must be explored and documented in order to prepare end-use property classification for miscellaneous use. Finally, if there is a timber property classification, i.e., requirement and property level for major end-uses as discussed in this paper and comprehensive information on wood properties of Sri Lankan timbers is available, then the timber industry will be able to define the technical information of timber which they need for their end-use applications. Subsequently the timber supplier can easily quote and supply the most suitable timber variety which is complying its technical performance with the requirement of end-use. Ruwanpathirana/Journal of Tropical Forestry and Environment Vol. 4, No 01 (2014) 1-13 13 References Hatharasinghe, S.M., 2013. Community awareness of timber in Sri Lanka. BSc Dissertation, University of Ruhuna, Sri Lanka. IAWA committee (1989). IAWA list of microscopic features for hard wood identification. IAWA Bulletin (N.S.)10, Netherlands. Ruwanpathirana, N.D., 2012. Sustainable utilization of timber resources in Sri Lanka. SOBA, Ministry of Environment, Sri Lanka, pp.56-70. Ruwanpathirana, N.D, 2014. Sri Lankan timber species: Wood properties and its uses, Ministry of Envirnment, Sri Lanka. Thelandersson, S., Hansson, M., 1999. Reliability of timber structural system-effects of variability and inhomogeneity. Lund University of Technology, Sweden. Withana, M. H., 2013. Classification of timber species in Sri Lanka and developing a model for price determination. BSc Dissertation, University of Ruhuna, Sri Lanka www.timber.lk (forestry education web site), 100 timber species in Sri Lanka. Accessed 15 th May 2014.