Detailed Specs: Mora
Scientific Name: Mora excelsa
Family: Caesalpiniaceae
Other Names: Nato, Nato rojo (Columbia), Mora de Guayana (Venezuela), Morabukea, Mora (Guyana), Moraboekea (Suriname), Pracuuba (Brazil)
The Tree
Usually grows 100-120 feet high and 1-3 feet in diameter with clear boles 60 feet or more above very large buttresses that may extend 15 feet up the trunk. Trees of M. excelsa grow from 160-200 feet high and 4 feet in diameter are reported.
The Wood
General Characteristics: Colour ranges from yellowish red brown, reddish brown or dark red with paler streaks. Sapwood is 2-6 inches wide with a yellowish to pale brown colour. The texture moderately fine to somewhat coarse and has a harsh feel. Luster is medium to high. The grain is straight and often interlocked. It has an astringent taste and a slightly sour odour.
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Weight: Basic specific gravity (ovendry weight/green volume) 0.76 to 0.84; air dry density 59 to 65 pcf.
Drying and Shrinkage: Drying reports are variable, generally rated moderately difficult to season; a slow rate of drying and careful stacking are suggested to keep warp and other degrade to a minimum. Boxed heart pieces tend to split. Kiln schedule T2-C2 is suggested for 4/4 stock and T2-C1 for 8/4. Shrinkage from green over dry radial 6.9%; tangential 9.8%; volumetric 18.8%.
Working Properties: This wood is moderately difficult to work but yields smooth surfaces in sawing, planning, turning or boring unless interlocked grain is present then there may be considerate ‘pick up’ and chipped grain.
Mechanical Properties: (First set of data based on the 2-in standard; second on the 2-cm standard).
|
Moisture |
Bending Strength (psi) |
Modules of Elasticity (1000 psi) |
Maximum Crushing Strength (psi) |
| Green (75)
12% Green (42) 12% |
12,630
22,100 13,600 24,400 |
2,330
2,960 2,150 2,790 |
6,400 11,840 7,150 12,700 |
Janka side hardness 1450 lb. for green material and 2300 lb. at 12% moisture content. Forest Products Laboratories toughness average for green and dry material is 228 in-lb. (5/8-in specimen)
Durability: Material from Suriname and Guyana is rated durable to very durable in resistance to brown rot and white rot fungi. Service life varies from 15-20 years in ground contact is reported. M. gonggrijpii is rated very resistant to dry-wood termites and M.excelsa is considerably less resistant and does not resist marine borers.
Distribution: M. excelsa: Widely distributed in the Guianas and in the Orinoco Delta of Venezuela. They are dominant on river levees and flood plains forming dense stands. M. Gonggrijpii: Restricted to Guyana and Suriname, a dominant species best adapted to hillsides on heavy clay soils.
Preservation: Sapwood responds readily to preservative treatments, heartwood resist to impregnation, penetration is very shallow and absorption is low.
Uses: Best suited for heavy construction such as jetties and foreshore work. It is particularly suitable for sleepers, wagon bottoms, and for both traditional and Mosaic flooring along with shipbuilding. In addition it can also be used for railroad crossties and high quality charcoal wood.
References
– Chundn of f, Mar tin (19 8 4), “ Tropical Timbers of the World. ” U SD A Fores t Service A g. Ha n db oo k No.6 0 7 .
