An Editorial Note: With the help of
members, the Rubber discussion mailing list is planning to do a series of
articles on exactly how little saplings turn into rubber trees, and then into
rubber products, written in laymans' language, but with special reference to allergy
sufferers, to help Rubber mailing list members understand a bit better the
various technical and economic processes which go on in the rubber producing
countries. This page is under construction. Announcements of new material, or
revisions, will appear on the Rubber discussion mailing list. These articles will
first appear for members only on the Rubber discussion mailing list, and then
shortly thereafter they will be made available here on the World Wide Web at:
http://www.immune.com/rubber/index.html Questions and requests
about latex Rubber allergy and/or these articles may be directed to the
Rubber discussion mailing list at mailto:Rubber@listserv.tamu.edu Here is the first in
this series of enlightening articles. |
Based on
a message to the Rubber discussion mailing list: Date: Tue, 4 Mar 1997 11:06:49 -0600 Reply-To: Rubber and latex allergy discussion list RUBBER@postal.tamu.edu From: David Shaw <Shaw@crain.demon.co.uk> Subject: Re: Questions To: RUBBER@postal.tamu.edu
Where Does
Rubber Come From?
Commercial natural rubber exports originate in:
Commercial natural
rubber latex exports originate in:
Data
in tonnes in the year 1995. Source IRSG |
|
As the map shows, these
countries are all located in South-east Asia.
Brazil provided the
world with the rubber tree, Hevea Brasiliensis, but that country no
longer plays any significant part in the world NR (natural rubber) trade. Seeds
were exported from the lower Amazon area of Brazil to London UK by Henry
Wickham, a local planter acting for the British Government in 1876.
The seeds were germinated at the Tropical Herbarium in Kew Gardens,
London later that year. From there seedlings were exported to Ceylon (Now Sri
Lanka). In 1877, 22 seedlings were sent from Ceylon to Singapore, where they
grew strongly, and the technique of tapping was developed.
Prior to this, the trees had to be felled before the latex could be
extracted.
By 1900, most of the techniques and agricultural practices required to
establish large plantations had been developed. One key technique was bud
grafting. This is essentially a cloning technique which ensures that
genetically identical trees can be produced in unlimited numbers.
The rubber industry often talks about high-yielding clones, or other
types of clone; and this is the basis of that terminology.
Over the next 40 years or so, the British in
Malaysia and the Dutch in Indonesia cleared large areas of rainforest to create
rubber plantations.
Simultaneously, local farmers saw the opportunities of rubber
cultivation, and planted small groves of trees to supplement their own income.
This gives rise to two types of rubber plantations in most producing
countries: the estates, or plantations and the smallholdings.
Smallholdings tend to produce solid rubber (see below) while estates are
essentially large-scale farms, with professional management. Most latex comes
from professionally managed estates.
Latex is often described as the sap of the Hevea tree. This is not an
accurate description. The sap runs deeper inside the tree, beneath the cambium.
Latex runs in the latex ducts which are in a layer immediately outside the cambium.
This highlights the skill of the tapper. If the cambium is cut, then the tree
is damaged, because the cambium is where all the growth takes place. Too much
damage to the cambium, and the tree stops growing and stops making latex.
All natural rubber originates in the Hevea tree, and it starts its
journey when the tree is tapped. Trees are rarely tapped more often than once
every two days.
A tapper starts the trek around the plantation before dawn. At each tree
a sharp knife is used to shave off the thinnest possible layer from the intact
section of bark. The cut must be neither too deep, nor too thick. Either will
reduce the productive life of the tree. This starts the latex flowing, and the
tapper leaves leaves a little cup underneath the cut.
In ordinary circumstances, this latex will normally coagulate into a
lump in the bottom of the cup, called 'cup lump.' If the plantation
manager wants to make latex, then the tapper must add a stabilising agent to
the cup. Usually this is ammonia, which prevents the latex from coagulating.
The tapper returns a few hours later and collects the stuff in the cup
-- either cup lump or latex. The double round trip usually finishes at about 2
pm.
FYI (for your information) , the tapper is very often at the bottom of
the educational scale. Many are women; illiteracy is high; pay is low. Child
care and education is rudimentary at best. Living conditions are quite
primitive and latex allergy awareness is extremely low.
|
If solid rubber is required, the cup lump, together with tree lace (the
remnants of the latex flow from the cut down to the cup) and other bits and
pieces are collected together and processed. That processing involves quite a
lot of heat, which destroys many (but not necessarily all) of the proteins. It
ends up as solid rubber. Depending on the method of processing and the final
purity of the material, the industry refers to it either as TSR (technically
specified rubber), or sometimes sheet rubber.
When latex is required--which covers about 10 percent of all NR
produced--the material is gathered on the tapper's return journey, poured into
containers and delivered to a processing station where it is strained and
concentrated. At no stage in the process is the latex heated. This means most
of the proteins remain in the latex.
More stabiliser is added and the latex goes into a centrifuge to
remove some of the water, and increase the rubber content of the latex. After
centrifuging, the material is known as latex concentrate, and contains
roughly 60 percent solid rubber and 40 percent other stuff (water, proteins
etc.). This (latex concentrate) is what is used in the
dipping process when making gloves. Is Latex Allergy All About Trade And Global
Competition?
There is a common belief in the Latex production sector that latex
allergies are hyped up in the United States. One argument often advanced is
that latex production workers in the producing countries do not become allergic, despite handling liquid
latex in hot, sweaty conditions. The counter-argument
is that this comparison (health care workers {HCWs} in the USA -vs-
plantation workers) is not valid, because of:
Nevertheless, the NR
producers have their own mind-set: They honestly believe
that this allergy issue is all about trade. They think that the
multi-national glove producers are imposing ultra-strict manufacturing limits
on gloves in order to drive smaller glove makers bankrupt and win back the
market share they lost to local manufacturers in the 1980s and 1990s. No matter how
unwelcome this point may be, it *is* how the South-east Asian manufacturers
(and some Europeans) see the issue. Cases of latex allergy are relatively
uncommon in Europe and very uncommon in Asia. Perhaps it is only a matter of
time before we get the pain that you have right now, but for the time being,
this view remains very common in the glove and latex industry outside the
USA. David Shaw |
|
·
Back To The Top Of This Article
·
A Brief Natural History of Latex Rubber Allergy
·
Where Does Rubber Come From?
·
Latex Is Not Made From Sap
·
Methods Of Latex Rubber Tapping
·
Processing Of Latex - Cup Lump or Liquid Concentrate
·
Is Latex Allergy All About Trade And Global Competition?
|
|