Thursday, October 22, 2009

Harvesting Rubber

PHOTO GROVE OF RUBBER TREES

Think AIDS, which sent the consumption of latex gloves in medical facilities skyrocketing. Think latex condoms, which are available at nearly every checkout stand in most countries, but seem insufficiently used.

Think rubber mattresses, expensive, but ever so comfortable, I hear, and they last a lifetime. Think rubber boots and tarps. Or think vehicle tires, which is actually where most of the world's rubber production goes.

Where it comes from is here. At least some small fraction of the often-preferred natural product (most 'rubber' is synthesized from petroleum) comes from right here on the Rio Dulce. The tree, Hevea Brasiliensis, is a native of Brazil, local to Central America and was used by the Mayans for their rubber game balls. In some respects (climate, rain, sun), this Rio Dulce area is ideal for rubber plantations, and there are several.

Also, as I learned at Tijax, another local plantation, their trees are a cross between the Brazilian and a Malaysian variety. As well, during dry conditions, as we have had recently despite the so-called rainy season, tapping stops in the interest of arboreal health.

In 1844 Charles Goodyear patented the process of vulcanisation, the process of mixing raw rubber with sulphur under extreme heat. This made a cheaper more elasticated rubber. Gloves, and condoms, are made by dipping glass forms into liquid rubber.

As usual, most everything I 'know' I Googled. Here's some more.

In the world scheme of things, far more rubber is produced in the vicinity of Malayasia, Thailand, and India. The forest that was cleared to grow these trees may have been ecologically preferable to the orderly rowed plantations; but economic forces have their own logic. In La Esmerelda almost all the workers I see are young men; but in Southeast Asia, it's often women's work, which is to say, poorly paid.

Whenever I asked my informants about the harvesting work, they always refer to 'ulli' trees. Come to find out that 'ulli' is a Mayan word, meaning blood, or rubber. Also, one of the sometimes contradictory factoids of Google indicates that hevea brasilensis and the maple tree may be related. Or not, but it seems like they should be.

For reasons of tree hydraulics, the trees are tapped at night or very early in the morning. On my daybreak walks, I sometimes see people still wearing head-lights, and hear the scritch of their knives as they move from tree to tree opening the veins, so to speak. They could be tapping new latex every couple days, as in Asia, but I don't think it's that intensive here. I should go out in the wee hours sometime to make sure, (but probably won't).
PHOTO TREE TAPPER WITH KNIFE

The tree, handled skillfully, is said to be good for twenty years of latex. Then its wood, stronger than oak (according to the rubber-wood-marketing board), can be used for furniture etc.

Mexico may be Guatemala's main latex rubber customer. Factoid: rubber is the only naturally-grown product used in the automotive industry, with the possible previous exception of silk.

The Asians seem to try to keep their rubber in liquid form, which means using ammonia as a solvent, according to a Google site. Or, according to the guide at Tijax, a muriatic acid solution is used.
PHOTO TAPPED TREE DRIPPING

Here, the latex rubber is harvested in 'cup form' and as 'tree lace' (peeled from the drip line). Its processing involves a lot of heat, which destroys at least some of the proteins (latex allergies are blamed on proteins), and the result is solid rubber.

The workers leave their 'cup forms' and 'tree laces' beside the road for a tractor to pick up. Gnats seem to like this powerfully scented 'ulli'.
PHOTO RUBBER PRODUCT

For more info see
http://www.irrdb.com/irrdb/NaturalRubber/History/History5.htm
http://www.immune.com/rubber/nr1.html#e, or try Google, and see where you bounce!

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