Friday, 2 December 2011

Elephant No. 61: Three-Dimensional Balsa Wood

For today's elephant, I decided to try a kit elephant that involves punching out a bunch of balsa wood pieces, then assembling them into a three-dimensional object by inserting various shapes into various slots.

Balsa wood comes from the Ochroma pyramidale, a tree that is native all the way from southern Brazil and Bolivia to southern Mexico. Today, it is also grown in many other Latin American countries, with Ecuador supplying as much as 95% of the world's commercial balsa. The name "balsa" comes from the Spanish word for "peanut".

Ochroma pyramidale is a tall and fast-growing tree that can reach heights of 30 metres (98 feet) within a mere ten to fifteen years. It usually establishes itself on abandoned agricultural land or cleared forests, paving the way for other plants. Because it grows so fast, its wood has a very low density—lower even than cork. The trees rarely live beyond thirty or forty years.

Acacia tree in the Tropical Gardens of Maui Iao Valley Road,
Maui, Hawaii
Photo: Forest and Kim Starr

The tree bears very large flowers that open in late afternoon and remain open through the night. The flowers often contain wells of nectar as deep as 2.5 cm (1 inch), and are a favourite of capuchin monkeys, kinkajous and bats.

Despite the softness of their wood, balsa trees are classified as hardwood because of the shape of their palmate leaves. The light weight of the wood comes from the fact that the tree has large, open cells that contain water. When harvested, the wood is kiln-dried for two weeks to draw off this moisture. Interestingly, the extended web of holes gives the wood surprising strength. Because it is low-density but high in strength, balsa is a popular wood for making models such as model bridges for testing, model aircraft, and even full-sized light aircraft such as the Second World War de Havilland Mosquito.

The de Havilland Mosquito B.XVI, September 30, 1944
Photo: Royal Air Force

Balsa is used to make laminates for boats and cars as well—including some models of the Chevrolet Corvette. Balsa logs were also used to build the Kon Tiki: a Polynesian-style raft sailed by Norwegian adventurer Thor Heyerdahl from Peru to Polynesia in 1947.

The Kon Tiki in 1947.

For today's elephant, I bought this kit for a mere two dollars. I thought it was a pretty good deal, given that it came with paints, a brush, and even a little square of sandpaper. What sort of elephant I might want to paint with these colours, I'm not sure, but it's still a good deal.

The kit came with no instructions, however, beyond these teensy diagrams on the back of the package, and the helpful suggestion that I "Match the corresponding pieces to make the model elephant."

This sounded straightforward enough until I actually tried to find the numbers. I began to think there was no Number 1 anywhere, and that these were stock shapes of some sort. This went on for a full twenty minutes of me staring at the diagrams and at the pieces, until I realized that the manufacturers had saved space by putting "1,9" and "2,10" on some of the key pieces. Because the numbers are so small and smeary, I had read this as "19" and "20". What they actually appear to have meant is that that particular piece would fit with Number 1 from one side of the front half of the body and Number 2 from the other side of the front half, and Number 19 from one side of the back half of the body and Number 20 from the other side of the back half. Confusing? You bet.

Even when I managed to figure out the numbering system, there's nothing to tell you which way to slide things into the slot. I got the entire body put together (much to my relief) before I realized that the legs would be upside-down if I tried to attach them. At that point, I just had to laugh.

Eventually I decided to take everything apart and start over, not paying attention to anything but the photograph of the wooden elephant on the front. I sorted the pieces into the recognizable parts—body, legs, trunk, tusks and ears—and a jumble of what was left.

Once I ignored the instructions—something I also find helpful when assembling Swedish kit furniture—it went fairly quickly. I definitely needed the diagram—and there were one or two points at which I did have to looked at the cursed numbers, usually to no avail—but eventually I got the body assembled, then the head.

The front legs have a disturbing tendency to fall off, for some reason, but I used all the pieces and they seem to fit in the right places, so I don't know what's wrong. Perhaps this is what the "use a spot of glue if things don't stay together" instruction refers to.

I like the final result, but it should come with much better instructions. Granted, I am no engineer, but I think even an engineering-oriented child would struggle with this. Better to have instructions like the ones I have for an umbrella ("Don't overwinding!") and a piggybank ("Go to the front to put in through the back") than mini-diagrams with illegible numbers.

Given how long this took, it's not getting painted in any colour. I may douse it with glitter and give it a Santa hat before Christmas if I want to torment it. But that's only if it doesn't lose its legs again.

Elephant Lore of the Day
One of the favourite trees of African elephants—and giraffes, for that matter—is the acacia. Given elephants' ability to eat between 149 and 169 kilograms (330 to 375 pounds) of plant matter a day, the risk to acacia trees is considerable.

Enter the ant. Ants act as protectors of the Acacia drepanolobium, which elephants rarely touch. The reason is that any elephant foolish enough to try eating this particular species of acacia is likely to end up with a swarm of angry ants crawling up inside its trunk.

To test their theory that ants were the reason elephants avoided the Acacia drepanolobium, scientists stripped the tree of its ants, while also adding ants to another species—the Acacia mellifera—which elephants love. When either tree had ants on it, the elephants would avoid those trees completely.

Ants on Acacia drepanolobium, Ngorongoro Conservation Area, Tanzania.
Photo: Pharaoh han, 2009

Despite their thick hide, elephants have extraordinarly sensitive skin, and their trunks have hundreds of thousands of nerve endings. Because elephants dislike ants inside their trunks, and appear to sense the presence of ants by smell, ant scent may one day be used to deter elephants from eating food crops grown on farms and plantations. This may reduce the incidence of human-elephant conflict, which usually results in casualities on both sides.

To Support Elephant Welfare

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