BASIC PROPERTIES OF MAHOGANY 

A. Physical Properties : 

1. Medium specific gravity : 0.54 

Suitable for high furniture and cabinet-making. other uses of amhogany are for panelling, automobile bodies, interior trim of boats, radio and phonograph cabinets, bodies of musical instruments, mouldings and other ornaments. 

2. Low volumetric shrinkage : 7.4% 

Most suitable at least in this country for high grade furniture and cabinet making and for other uses where shrinkage is of imporatnce. 

3. Medium strength : MOR = 62.4 MPa 

For medium construction such as general framing, panelling, conventional furniture, flooring, door and windows frames, pallets, joist, scaffoldings, shingles, siding boards. 

Mahogany is a medium-weight timber which is rather soft. The heartwood is reddish or pinkish, the color darkening with age to a deep red or brown,, sapwood usually yellowish and up to 400 mm wide. The density is 500 - 800 (-850) kg/m³ at 15% moisture content. the grain of the wood is interlocked, sometimes straight, texture fine to moderately coarse. the surfaces are glossy, and the wood is often nicely figured because of the irregular grain. 

Test in Indonesia is showed the following mechanical properties at 15% moisture content: 

• Modulus of rupture : 55 - 61 N/mm² 
• Modulus of elasticity : 9,000 - 9950 N/mm² 
• Compression // to grain : 36 - 40 N/mm² 
• Shear : 4 - 7.5 N/mm² 
• Cleavage : 51 - 55 N/mm (radial) 
• 58 - 64 N/mm (tangential) 
• Janka side hardness : 2,650 - 3,840 N 
• Janka end hardness : 3,700 - 3,840 N 

The rates of shrinkage are: 

• from green to 15% moisture content - 0.9% radial and 
• 1.3% tangential, 
• from green to 12% moisture content - 1.2 - 1.4 radial and 1.8 - 2.2% tangential 
• from green to oven dry - 3.0 - 3.3% radial and 
• 4.1 - 5.7% tangential 

Mahogany seasons well and easily without much checking or distortion. Boards of S. macrophylla wood can be air dried in 11 weeks (50 mm thick) and 6 weeks (25 mm thick) from 40% moisture content to 15%. The wood kiln dries satisfactorily when moderate schedules are used (temperatures 43 - 76^oC and corresponding relative humidity of 75 - 33%) Boards of 50 mm thick can be kiln dried in approximately 8 days, and boards of 25 mm in 4 days. After drying, the wood is stable in service. 

Mahogany saws, planes and moulds easily in both green and dry condition. In general, it finishes to a smooth surface, but a wooly surface may occur on bands of reaction wood or interlocked grain. Finishing is easy and the wood takes an excellent polish. Gluing and nailing properties are good but discoloration in contact with iron, copper and brass may occur under humid conditions. Mahogany slices and rotary cuts into fine decorative veneer, without preliminary treatment, at a peeling angle of 92^o. The veneer can be glued with casein extended with 30% lime, to produce plywood of satisfactory quality. Satisfactory results are obtained with pulping (kraft pulp yield of 49.5%). 

The heartwood of trees from natural stands can be reasonably durable for application-grown wood is not considered suitable for applications in contact with the ground. Graveyard tests in Indonesia showed an average service life in contact with the ground of 2.7 years for S. macrophylla and 3.3 years for S. mahagoni. The wood is resistant to wood-rotting fungi. The sapwood is susceptible to Lyctus borer attack and the heartwood may also be attacked by pinhole borers and termites; the wood has little resistance to marine borers. nahogany is resistant to impregnation with preservatives by pressure methods, but plantation-grown wood can be amenable to boron diffusion techniques.