BALSA  -  A - Z of WOOD





Balsa lumber is very soft and light, with a coarse, open grain. The density of dry balsa wood ranges from 40 to 340 kg/m3, with a typical density around 160 kg/m3. Balsa is the softest wood ever measured using the Janka hardness test (22 to 167 lbf). The wood of the living tree has large cells that are filled with water. This gives the wood a spongy texture. It also makes the wood of the living tree not much lighter than water and barely able to float. For commercial production, the wood is kiln-dried for about two weeks, leaving the cells hollow and empty. The large volume-to-surface ratio of the resulting thin-walled, empty cells gives the dried wood a large strength-to-weight ratio because the cells are mostly air. Unlike naturally rotted wood, which soon disintegrates in the rainforests where balsa trees grow, the cell walls of kiln-seasoned balsa wood retain their strong structure of cellulose and lignin.

Because it is low in density but high in strength, balsa is a very popular material for light, stiff structures in model bridge tests, model buildings, and construction of model aircraft; all grades are usable for airworthy control line and radio-controlled aircraft varieties of the aeromodeling sports, with the lightest "contest grades" especially valuable for free-flight model aircraft. However, it is also valued as a component of full-sized light wooden aeroplanes, most notably the World War II de Havilland Mosquito.

Balsa is used to make wooden crankbaits for fishing, especially Rapala lures.

Sticks of dried balsa are useful as makeshift pens for calligraphy when commercial metal nibs of the desired width are not available.

Balsa wood is often used as a core material in composites; for example, the blades of many wind turbines are partly of balsa. In table tennis bats, a balsa layer is typically sandwiched between two pieces of thin plywood made from other species of wood. Balsa wood is also used in laminates together with glass-reinforced plastic (fiberglass) for making high-quality balsa surfboards and for the decks and topsides of many types of boats, especially pleasure craft less than 30 m in length. On a boat, the balsa core is usually end-grain balsa, which is much more resistant to compression than if the soft balsa wood were laid lengthwise.

Balsa is also used in the manufacture of "breakaway" wooden props such as tables and chairs that are designed to be broken as part of theatre, movie, and television productions.

The fifth and sixth generations of the Chevrolet Corvette had floor pans composed of balsa sandwiched between sheets of carbon-fiber-reinforced plastic.

Norwegian scientist and adventurer Thor Heyerdahl, convinced that early contact between the peoples of South America and Polynesia was possible, built the raft Kon Tiki from balsa logs, and upon it his crew and he sailed the Pacific Ocean from Peru to the Polynesian Tuamotu Archipelago in 1947. However, the Kon Tiki logs were not seasoned and owed much of their (rather slight) buoyancy to the fact that their sap was of lower density than sea water. This serendipitously may have saved the expedition, because it prevented the seawater from waterlogging the wood and sinking the raft. Though, it did eventually almost submerge.

Balsa wood is also a popular wood type used in the arts of whittling, and surfing. In the making of picture frames, balsa was often used in a baroque style because of the ease of shaping the design.




Birch, Silver

Douglas fir
European Beech


Oak, European
Pitch Pine

Redwood, European
Sitka Spruce
Southern Yellow Pine
Western Hemlock
Western Red Cedar
Whitewood, European



Wood is good. It is a natural material growing all over the planet as trees. As these trees grow, they convert carbon dioxide to timber for humans to harvest and cut up in sawmills, after the dead tree has had time to season.


Planting more trees than we cut down is one way of sustainably managing forests, so that we don't upset the balance and reduce the carbon sink that keeps our planet cool. Unfortunately, some logging is not properly policed, such as the clearing of large swathes of jungle, to grow cash crops.


We should be going the other way, re-wilding areas, instead of farming them. But, wood is useful to build houses and make furniture. Hence, we should plan our assault on the natural world more carefully. Even if it means creating laws to stop the plunder in the Amazon and other rainforests.


We also need wood to make plywood, MDF, stirling board and chipboard. Wood is the basis of paper and cardboard. Pound for pound, some timbers are stronger than steel.








WOOD - This building dating from C. 1900 is of wooden construction, seen here undergoing re-roofing in 2018. When built the timbers were not treated. Amazingly, despite serious flora invasion and insects, the building is in relatively good condition. A good example of carbon lock, and something that perhaps a circular economy should be based on.








The generating station just 400 yards from Gardner (High) Street, in the Sussex village of Herstmonceux, is the oldest surviving early example of municipal electricity generation, in a rural setting in the whole world. For this reason the generating buildings are now being converted by the Lime Park Heritage Trust. At present, the complex enjoys no reasonable of beneficial use to pay for general maintenance and security, as a heritage asset in a relatively exposed position, and constructed of timber. Fortunately, the walkers in this field are a great bunch. Very friendly and chat with each other. Also keeping an eye out for anything out of the ordinary.












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