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Blunting Effect Boring Carving Comments Common Names Common Uses Countries of Distribution Cutting Resistance Distribution Overview Drying Defects Ease of Drying Environmental Profile Family Name Gluing Grain Heartwood Color Kiln Drying Rate Kiln Schedules Light-Induced Color Change Luster Mortising Moulding Movement in Service Nailing Natural Durability Natural Growth Defects Numerical Data Odor Painting Planing Polishing Product Sources References Regions of Distribution Resistance to Impregnation Resistance to Splitting Response to Hand Tools Routing & Recessing Sanding Sapwood Color Scientific Name Screwing Staining Steam Bending Strength Properties Texture Toxicity Trade Name Tree Size Turning Varnishing Veneering Qualities		Scientific Name Grevillea robusta Trade Name Silky oak Family Name Proteaceae Common Names Australian silky oak, Australian silky-oak, Carvalho sedoso, East African silky oak, Gravilea, Greirllea, Grevilea, Grevilia, Grevillea, Helecho, Kawilia, Lacewood, Pino rojo, Roble de pelota, Roble de seda, Roble redoso, Silk oak grevillea, Silky oak, Southern silky oak, Tuggan-tuggan Regions of Distribution North America, Oceania and S.E. Asia Countries of Distribution  [VIEW MAP] Australia, South Africa, United States Common Uses Agricultural implements, Balusters, Bedroom suites, Boxes and crates, Brush backs & handles, Building construction, Building materials, Cabinetmaking, Casks, Chairs, Chests, Coffins, Concealed parts (Furniture), Concrete formwork, Construction, Cooperages, Desks, Dining-room furniture, Domestic flooring, Dowell pins, Dowells, Drawer sides, Excelsior, Factory flooring, Fine furniture, Floor lamps, Flooring, Flooring: industrial heavy traffic, Furniture , Furniture components, Furniture squares or stock, Furniture, Hatracks, Heavy construction, Interior construction, Joinery, Kitchen cabinets, Light construction, Living-room suites, Moldings, Office furniture, Packing cases, Paneling, Parquet flooring, Particleboard, Plywood corestock, Plywood, Pulp/Paper products, Pulpwood, Radio - stereo - TV cabinets, Rustic furniture, Stairworks, Toys, Turnery, Vats, Vehicle parts, Veneer, Veneer: decorative Environmental Profile Endangered Extinct Abundant/Secure Status has not been officially assessed Distribution Overview Native to eastern Australia but planted extensively as a shade tree for coffee and tea plantations and as an ornamental in tropical and subtropical regions. Can be found in Tanganyika and some areas of the U.S. It has gained widespread popularity in warm temperate, subtropical and tropical highland regions of many countries, originally as a shade tree for tea and coffee and more recently as an agroforestry tree for small farms. It provides economically valuable products including timber, poles, firewood and leaf mulch; it is easy to propagate and establish and is relatively free of pests and diseases; its proteoid roots help it grow in low-fertility soils; it does not compete strongly with adjacent crops; and it tolerates heavy pruning of its roots and branches. The natural habitat of G. robusta is in northern New South Wales and southern Queensland, Australia, where it occurs from the east coast to as far west as the Bunya Mountains, Queensland, up to an altitude of 1120 m. Heartwood Color Red Brown Pink Yellow Purple Orange Reddish brown Pale brown Brown Yellow to golden-yellow to orange Red Pink when freshly cut The heartwood is a distinct pink or light red when freshly cut, darkening to pale or red-brown upon drying. Sapwood Color White Yellow Pink Red Brown White to yellow Well defined Straw colored to grayish-white Same as heartwood Clearly differentiated from the heartwood Grain Figure Rays (figure) Straight Wavy Distinct (figure) Closed Even Mottled (figure) Stripe (figure) Growth rings (figure) Rays figure Straight Wavy Distinct figure Striped figure Figure shows mottle Occasionally wavy Clear growth rings (figure) Broad rays and alternating darker and lighter colored bands combine to form a woven pattern which gives Silky-oak a very striking figure. Texture Fine Medium Very fine Medium coarse to coarse Medium Coarse Fair to medium coarse The wood is diffuse porous, and the texture is described as fairly coarse. Luster Medium High Low Lustrous Rays are highly lustrous, but background wood tissue is rather dull in appearance. Natural Growth Defects Gum/resin streaks Gum and mineral deposits Natural Durability Susceptible to insect attack Resistant to termites Non-resistant to powder post beetles Durable Moderately durable Very durable Resistant to powder post beetles Perishable Non-resistant to termites Non-durable Moderately durable Susceptible to attack from powder post (Lyctid & Bostrychid) beetles Non durable Susceptible to marine borer attack Susceptible to attack from termites (Isoptera) Resistant to attack from termites (Isoptera) Pinworms (ambrosia beetles) may be present in the felled log Durable Moderately resistant to termite (Isoptera) attack Moderately resistant to attack by termites Moderately resistant to attack by pinhole borers Moderately resistant to attack by marine borers Heartwood is susceptible to wood staining fungal attack Odor No specific smell or taste Light-Induced Color Change Darker Toxicity Some toxic effects Dermatitic effects Material in the green or dry condition may cause skin irritation in some individuals. Finished wood is safe to handle Kiln Schedules Dry at a slow speed UK=C US=T3C2/T3C1 Fr=3 UK=A US=T2D4/T2D3 Fr=1 T3 - C2 (4/4); T3 - C1 (8/4) US Kiln Drying Rate (in days) is rather slow Kiln Drying Rate (in days) is fairly rapid Drying Defects Checking Splitting Distortion Resin Exudation Moderate surface checking Moderate end spitting Moderate twist/warp Slight twist/warp Slight surface checking Severe end splitting 1 inch (2.5 cm) thick boards are relatively easy to air-dry. There is some tendency for thicker stock to distort, check, and end-split especially if boxed heart is present. Honeycombing and twisting may also occur under harsh kiln-drying conditions. Ease of Drying Fairly Easy Moderately Difficult to Difficult Variable Gum Exudation Rapidly Thick Stock Requires Care Moderate Mild drying schedule recommended Easy Dries slowly Material containing boxed heart has a high tendency to degrade during seasoning Kiln Drying Rate Naturally dries quickly Slow (18-28 days for boards < 32 mm, to 52-84 days for boards >= 63 mm) Fairly rapid (11-17 days for boards under 32 mm, to 31-51 days for boards greater than 63 mm) Tree Size Trunk diameter is 100-150 cm Tree height is 30-40 m Tree height is 20-30 m Tree height is 50-60 m Tree height is 40-50 m Bole length is 20-30 m Bole length is 10-20 m Tree height is 10-20 m Trunk diameter is 150-200 cm Sapwood width is 10-15 cm Sapwood width is 5-10 cm The species is often displaced on favorable growing sites by Eucalyptus, which consists of numerous species some of the largest hardwoods. Product Sources Silky oak is costly on the US market because of transportation costs and special processing costs required to maximize its figure. The material is available in adequate supplies in its native Australia. Comments Deposits and Other Growth Features Silky-Oak is closely similar to American mahogany (Swietenia ) in most strength properties. It is rated much weaker than all the true Oaks, but its strength properties are adequate for use in fine furniture. Vessels contain red deposits, and some trees contain small knots and numerous gum streaks Blunting Effect Little Moderate Boring Fair to good results Fairly easy to very easy Very good results Moderately easy Easy The timber has very good woodworking properties. It responds well to hand and machine tools in boring, moulding, mortising and all woodworking operations to produce clean surfaces. It works readily with both hand and machine tools. Carving Fair to Good Results Fairly Easy to Very Easy Very Good to Excellent Results Good carving characteristics Cutting Resistance Easy to saw Fairly Difficult to Very Difficult to saw Cutting Resistance with green wood is easy Cutting Resistance with dry wood is easy Cutting Resistance with dry wood is moderate Green material saws easily, but sawteeth may become clogged by gum. Seasoned wood has better sawing properties. Gluing Fairly Easy to Very Easy Fair to Good Results Moderate gluing properties Mortising Fair to Good Results Fairly Easy to Very Easy Finishes well Moderately easy to mortise Easy to mortise Moulding Fair to Good Results Fairly Easy to Very Easy Good finishing results Easy to mould Moulding ease is moderate Movement in Service Excellent Stability - Small Movement Fair to Good Stability - Medium Movement Medium The timber has medium dimensional stability after manufacture. Nailing Fairly Easy to Very Easy Fair to Good Results Fairly Difficult to Very Difficult Poor to Very Poor Results Nails hold poorly Holds satisfactorily Holds nails well Good nailing qualities Easy to nail Silky-Oak has good nailing qualities and can accept even rather large diameter fasteners without splitting. Planing Fairly Easy to Very Easy Fair to Good Results Very Good to Excellent Results Ease of planing is moderate Easy to plane Planes well, to a good finish Planes to a satisfactory finish Fair planing properties Dominant rays tend to cause chipping during planing operations, but silky-oak is more pleasant to work with than most of the true Oaks because it is less dense. Resistance to Impregnation Resistant heartwood Permeable sapwood Resistant sapwood Heartwood is moderately resistant Sapwood is permeable Heartwood is permeable Response to impregnation is variable Resistance to Splitting Poor Response to Hand Tools Easy to Work Fairly Difficult to Difficult to Work Responds Readily Easy to machine Moderate working qualities Good response to hand tools Routing & Recessing Fair to Good Results Fairly Easy to Very Easy Sanding Fair to Good Results Fairly Easy to Very Easy Good sanding qualities Screwing Fairly Easy to Very Easy Fair to Good Results Turning Fair to Good Results Fairly Easy to Very Easy Poor results Easy to turn Although Silky oak is highly figured, it responds remarkably well in turning operations Veneering Qualities Veneers easily Suitable for peeling Veneers moderately easy No drying degrade Easy to cut There is slight to moderate drying degrade and the potential for buckles and splits Suitable for slicing Suitable for peeling Steaming required to prepare bolts No drying degrade. Dries flat without splitting Good gluing qualities Silky-Oak is reported to produce some of the most attractive inlays when radially sliced into veneers. The combination of highly lustrous rays over rather dull background tissue reflect light in a manner which makes radially sliced veneers very attractive. Steam Bending Fair to Good Results Fairly Easy to Very Easy Moderate Painting Fair to Good Results Fairly Easy to Very Easy Polishing Fair to Good Results Very Good to Excellent Results Fairly Easy to Very Easy Satisfactory results Very good Good results Material with lifted rays, caused by moisture changes, may need further surface preparation or sanding in order to achieve good polishing results. Staining Fair to Good Results Very Good to Excellent Results Fairly Easy to Very Easy Finish is generally good Finish is generally satisfactory Very good staining properties Varnishing Fair to Good Results Fairly Easy to Very Easy Strength Properties Density (dry weight) = 38-45 lbs/cu. ft. Bending strength (MOR) = low Modulus of Elasticity (stiffness) = very low Density (dry weight) = 31-37 lbs/cu. ft. Max. crushing strength = low Shrinkage, Radial = very small Max. crushing strength = medium Shearing strength (parallel to grain) = very low Shrinkage, Tangential = moderate Shearing strength (parallel to grain) = low Hardness (side grain) = soft Shrinkage, Tangential = small Shrinkage, Tangential = very small Shrinkage, Radial = small Modulus of Elasticity (stiffness) = low Shrinkage, Tangential = fairly large Shrinkage, Radial = moderate Shearing strength (parallel to grain) = medium Bending strength (MOR) = medium Numerical Data Item Green Dry English Bending Strength 6299 10507 psi Density 38 lbs/ft3 Hardness 927 lbs Maximum Crushing Strength 2929 5090 psi Shearing Strength 1267 psi Stiffness 1062 1191 1000 psi Toughness 93 inch-lbs Specific Gravity 0.47 0.54 Weight 36 28 lbs/ft3 Radial Shrinkage 2 % Tangential Shrinkage 7 % Item Green Dry Metric Bending Strength 442 738 kg/cm2 Density 608 kg/m3 Hardness 420 kg Maximum Crushing Strength 205 357 kg/cm2 Shearing Strength 89 kg/cm2 Stiffness 74 83 1000 kg/cm2 Toughness 107 cm-kg Specific Gravity 0.47 0.54 Weight 576 448 kg/m3 Radial Shrinkage 2 % References Arno, J. 1992. Grevillea robusta - Silky oak. In A Guide to Useful Woods of the World, Flynn Jr., J.H., Editor. King Philip Publishing Co., Portland, Maine. Page 175-176. Audas, J.W.,Native Trees of Australia,Whitcombe & Tombs PTY. Ltd Australia - N.S.W. Forestry Commission,1968,Working Properties of some Native and Imported Timbers,Forestry Commission of New South Wales, Technical Publication No.8 Australia - N.S.W. Forestry Commission,1988,Furniture Timbers of New South Wales,Forest Commission, N.S.W., Aust. Tech. Publication No.1 Banks, C.H., Schoeman, J.P., Otto, K.P.,1977,The Mechanical Properties of Timbers with particular reference to South,Africa,South African Forestry Research Institute Bulletin,(Ed.,Schoeman, J.P. 1973 & Otto K.P. 1976,No.48 Banks, C.H.,1954,The Mechanical Properties of Timbers with Particular Reference to those,grown in the Union of South Africa,Journal of the South African Forestry Association,No. 24 pp.44-65,[South,African Forestry Journal] Banks, C.H.,1970,The Durability of South African Wood and Wood Base Building Materials,South African Forestry Journal,No.75 Berni, C.A., Bolza, E., Christensen, F.J.,1979,South American Timbers - The Characteristics, Properties and Uses of 190,Species,C.S.I.R.O Div. Building Research Bois, P.J.,1966,The Strength Properties of Tanzania Timbers,Tanzania Forest Div. Util. Sec. Moshi Tech. Note, No.35 Bolza, E. and N.H. Kloot. 1963. The Mechanical Properties of 174 Australian Timbers. Division of Forest Products Technological Paper No. 25. Commonwealth Scientific and Industrial Research Organization, Melbourne, Australia. Bolza, E., Keating, W.G.,1972,African Timbers - the Properties, Uses and Characteristics of 700 Species,C.S.I.R.O. Div. of Building Research Bolza, E., Kloot, N.H.,1963,The Mechanical Properties of 174 Australian Timbers,C.S.I.R.O. Division of Forest Products Technological Paper,No.25 Bolza, E.,1976,Timber and Health,Div. Building Res. C.S.I.R.O. Australia Brown, W.H.,1978,Timbers of the World, No. 8 Australasia,TRADA, Red Booklet Series Bryce, J.M., Norcross, H.,1961,The Resistance of Tanganyika Timbers to Impregnation,Tanzania Forest Dept. Util. Sec .Tech. Note,No.28 Chudnoff, M.,1984,Tropical Timbers of the World,U.S.A. Department of Agriculture, Forest Service, Forest Products,Laboratory, Madison. Farmer, R.H.,1972,Handbook of Hardwoods,HMSO France - C.T.F.T./C.T.B.,1982,Guide pour le Choix des Essences Deroulables-pour la fabrication du,contreplaque,C.T.F.T./C.T.B. France Gay, F.J., Et al,1955,Standard laboratory colonies of termites for evaluating the resistance of,timber, timber preservatives and other materials to termite attack.,C.S.I.R.O., Australia Bulletin,No.277 HMSO. 1972. Handbook of Hardwoods, 2nd Edition. Revised by R.H. Farmer. Department of the Environment, Building Research Establishment, Princes Risborough Laboratory, Her Majesty's Stationery Office, London. Howard, A.L.,1948,A Manual of Timbers of the World.,Macmillan & Co. Ltd. London 3rd ed. I.U.F.R.O.,1973,Veneer Species of the World,Assembled at F.P.L. Madison on behalf of I.U.F.R.O. Working Party on,Slicing and Veneer Cutting Keating, W.G., Bolza, E.,1982,Characteristics properties and uses of timbers. South East Asia, Northern,Australia and the Pacific,C.S.I.R.O. Div. Chemical Technology,Inkata Press,1 Kloot, N.H. and E. Bolza. 1961. Properties of Timbers Imported into Australia. Division of Forest Products Technological Paper No. 12. Commonwealth scientific and Industrial Research Organization, Melbourne, Australia. Murira, K.,1984,Natural Durability Tests of Tanzanian Timbers 1955 - 1982,Tanzania Forestry Research Institute, Timber Utilisation Research Centre,,Moshi. Patterson, D.N.,1963,The strength of Kenya timbers, their derivation and application,Kenya Forestry Department Research Bulletin,No.23 Poynton, R.J.,1972,Characteristics and uses of trees and shrubs,South African Forestry Department Bulletin,No.39 Scott, M.H.,1935,Weights of South African Growth Timbers,South African Department of Agriculture and Forestry Bulletin,No.145,Forest Products Institute, Forestry Series No.1 Scott, M.H.,1953,Utilisation Notes on South African Timbers,South African Forestry Department Bulletin No.36 Swabey, C.,1941,The Principal Timbers of Jamaica,Department of Science and Agriculture Jamaica Bulletin No.29 Takahashi, A.,1975,Compilation of data on the Mechanical Properties of Foreign Woods (Part 2,Central and South America,Shimane University, Japan, Research Report on Foreign Wood No.4 Takahashi, A.,1978,Compilation of Data on the Mechanical Properties of Foreign Woods (Part,III) Africa,Shimane University, Japan, Research Report on Foreign Wood No. 7 Tanzania - Timber Marketing Co. Ltd.,1978,Timber from Tanzania Tanzania Forest Department,1960,The Natural Durability of Local Timbers,Tanzanian Forest Dept. Tech. Note,No.14 Tanzania Forest Department,1961,The Movement of Timbers Technical Note No.29,Tanzania Forest Department, Utilisation Division Technical Note Tanzania Forest Department,1966,Flooring Timbers,Tanzania Forest Div. Util. Sec. Moshi - Timbers of Tanganyika Tanzania Forest Division,1962,Grevillea robusta (African silky oak: Southern silky oak: Kawilia,Tanzania Forest Div. Util. Sec. Moshi - Timbers of Tanganyika Tanzania Forest Division,1966,Kiln Drying Schedules for Tanzania Timbers Technical Note no.38,Tanzania Forest Div. Util. Sec. Moshi Uganda Forest Department,1954,The Mechanical Properties of some Ugandan Timbers,Uganda Forest Department Timber Leaflet,No.1 Uganda Forestry Department,1954,Pilot tests of strength properties of some Ugandan grown timbers,Uganda Forest Department Timber leaflet No. 46 Youngs, R.L.,1964,Hardness, density and shrinkage characteristics of silk oak from Hawaii,U.S.A. Department of Agriculture, Forest Service, Forest Products,Laboratory, Madison Research Note 074