American mahogany

American mahogany

Mahogany, American Mahogany, Swietenia Mahogany

Origin:

American mahogany trees are found in tropical forests in Central and South America on the territory of countries such as: Ecuador, Panama, Costa Rica, Bolivia, Mexico, Guatemala, Peru, Nicaragua, Honduras and Brazil. These trees grow well on medium to heavy soils up to an altitude of 1,500 m a.s.l.

Tree habit:

The trees of this species, with their spreading crowns, grow to a height of 30-40 metres. However, specimens with a record height of 50-60 metres have been known. The trunks of these trees are usually straight with a cylindrical shape and can be up to 2 m in diameter at the butt. This is considerably larger if there is a butt swell at the base of the trunk, common in this species. It is a fast-growing species.

Structure type:

Diffuse-vascular, vessels mainly distributed singly or in clusters (2-3 each), visible to the naked eye. There are between 2 and 12 vessels per 1 mm² of cross-section (average 7).

Sapwood:

Narrow (2 to 5 cm wide), grey-white in colour.

Heartwood:

With varying colours (from light pink-cinnamon to red-cinnamon to red-brown). When exposed to light and oxygen in the air, heartwood darkens intensely – to a cinnamon-brown colour.  

Fragrance:

It does not emit a characteristic odour.

Pattern:

The American mahogany wood has a mostly regular, stratified structure, visible by the arrangement of several rows of medullary rays. They can be homo or heterogeneous. A second characteristic is the alternating (left and right) twisting of the fibres, visible on the radial section as regular bands, usually 1-3 cm wide. In addition to the typical "striped" pattern, woods with a more complex pattern, associated with a curled or wavy arrangement of fibres or the presence of branches (e.g. pyramidal arrangement), are encountered, often producing very original and interesting visual effects. The annual increment boundary is evident by the presence of narrow strands of terminal parenchyma. In these areas there are often gum-resin ducts. The second form of parenchyma, but present in very small numbers, is the paratracheal parenchyma (from poor to perivascular, surrounding the vessels with a ring).   

Typical defects:

Striped fibre twist.   

Mahogany wood properties:

According to the six-grade density scale, American mahogany is a moderately light wood (grade IV). The average density for the air-dry state is 520 kg/m³. The species has low shrinkage and low anisotropy. Contraction in the tangential direction is only 1.5 times greater than shrinkage in the radial direction. These characteristics make the wood dimensionally stable (it has a low tendency to warp and crack). According to Monnin's classification, it belongs to low shrinkage wood. Despite its low density, the wood is strong. The average modulus of elasticity exceeds 9 GPa and the average compressive strength along the fibres – 50 MPa. The relatively low tensile strength (compared to others) is due to the fibre twist found in mahogany, which gives it an attractive striped pattern on the radial section.

Similar species:

Other American mahoganies of the genus Swietenia, African mahoganies of the genus Khaya (Acajou) or Entandrophragma (Sapeli, Sipo)

Working:

The wood is easy to work with machines and hand tools. It is more difficult to work wood with a more intricate grain system – the fibres are torn out when planing and the surface is rough. The presence of tension wood gives a similar effect of unevenness and surface roughness. However, these surfaces can be smoothed by sanding. Dust generated during working can irritate the eyes and respiratory tract. 

Joining:

This wood bonds well and gives durable joints when using metal fasteners. 

Finishing:

The wood paints and saturates well, but the use of strongly alkaline chemicals is not advisable as they can cause local discolouration

Availability:

width 18-23 cm,

length 3,10 m,

thickness 52 mm,