A fine grain

7th March 2003 at 00:00
Abstract art? Textile design? Wallpaper? Symmetrical yet varied, this natural structure reveals a hidden harmony

Aphotograph of the grain in a piece of mahogany (magnified 400 times) reveals how its cell structure is composed of tubes and pores. Every part of this structure is important. Woods are classified as soft or hard according to their density: mahogany is a hardwood. It consists of water-conducting cells (tracheids and vessels) and tightly packed fibre cells composed of lignin (a polymer specific to wood) and cellulose. The more lignin a wood contains, the heavier and harder it is and the smaller the air spaces (lumens) in the cell walls. Sapwood (new wood) is produced annually by these structures, which carry nutrients horizontally and vertically. Some woods (ironwoods) are so dense with lignin that they sink in water. Softwoods, on the other hand, have large air spaces, but these also sink when lumens are waterlogged.

There are several species of mahogany, one of which is related to the rose family, like hawthorn, peach and mountain ash; the main forms originate from tropical South America and have been introduced to other rainforests worldwide. These huge trees can top 50 metres, and the trunk can reach 12 metres in circumference.

For centuries, mahogany has been much in demand for its deep, dark glow.

Makers of furniture and musical instruments cut it either for "cathedral" grain or (as here) "ribbon stripe" grain; polishing develops a lustrous patina which brings out the "figuring" or pattern of the structure.

Stately mahoganies are now rare in many tropical forests. In Cuba, harvesting the finest mahogany is illegal, apart from trees blown down in storms, but woodworkers consider the patina on Honduran farmed mahogany to be much inferior. So valuable is the trade in fine mahogany that many murders of indigenous peoples by loggers have been reported. A "grey" market is booming. Brazilian TV recently revealed that mahogany could face extinction if illegal exploitation is not curtailed. But, according to Greenpeace, mahogany trees in the Amazon basin continue to be illegally felled and exported, under cover of counterfeit documents - to countries that include the US, the UK and Spain - even though exploitation, transport and trade in mahogany has been prohibited in Brazil since October 2001.

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