to make a cut in the bark of the rubber tree
to harvest the latex.
Tapping is difficult to do well.
You must take care how you do it.
For a good tapping,
make a good cut;
harvest the latex well;
harvest the latex at the right time.
Before we see how to make the tapping,
let us look back at what we learned
in the course on plant stems.
Let us see how the trunk of the rubber tree is made.
THE TRUNK OF THE RUBBER TREE
If you cut through a trunk, you see several layers.
On the outside is the bark,
which is about 6 millimetres thick.
In the centre is the wood,
Between the wood and the bark
there is a layer which cannot be seen with the naked eye,
because it is very thin.
This is the cambium layer.
The cambium makes the tree grow,
by producing wood and bark.
So you must not damage it
if you want the tree to grow normally.
If you look at rubber tree bark with a microscope,
you will see several layers.
One of these, the deepest, contains little channels
called lactiferous vessels
because they contain latex.
This layer is next to the cambium.
The lactiferous vessels are little tubes
that produce latex.
In tapping, you cut these little tubes containing latex.
But you must take care not to cut the cambium.
When a tree is 50 centimetres in circumference
at a height, of 1 metre from the ground,
that is, 5 years after it has been put in the plantation,
you can begin to tap the tree.
To start the tapping, take a metal ribbon
attached to a wooden lath 1.10 metres long.
This metal ribbon
is at an angle of 30 degrees to the horizontal.
Roll the metal ribbon round the tree.
With an awl (an iron point), make a cut along the ribbon.
The cut ends when you have gone right round the tree.
The beginning of the cut and the end of the cut
are on the same vertical line.
With the awl make a vertical channel
from the lower edge of the cut.
The cut and the channel must be deepened.
This is done with a gouge, a tool
that is used by pushing it so as to remove bark.
Push the gouge several times
along the cut and the channel,
taking away a very little bark at a time.
You do this so as to cut the bark
as close as possible to the cambium,
but without damaging it.
As the bark is about 6 millimetres thick,
the cut must be 4.5 millimetres deep.
The vertical channel is 25 centimetres long.
At the lower end of this channel, put a gutter.
Below that, put a cup called a latex cup.
Tie it to the tree.
The latex flows along the cut, into the channel,
and at last, through the gutter,
it drops into the cup.
The latex that flows when you first make the cut
is not good for harvesting,
so for several days you do not harvest any latex,
but all the same you must come and cut the bark.
Early in the morning,
go to the plantation to reopen the cut.
Begin by taking away the latex
that has coagulated on the cut
and put it in a basket.
Take away also any latex
that has flowed over the bark.
Then, with the gouge,
take out a little piece of bark, 1.5 millimetres thick,
without touching the cambium.
Make the cut as far as 1.5 millimetres from the cambium.
The latex flows along the cut, then down the channel,
and through the gutter, it drops into the latex cup.
Then, 4 hours later,
come again and collect what is in the cup.
Two days afterwards, clean out the cup.
One man can tap 440 trees a day.
The man who does the tapping is called the tapper.
If you make the cut badly, and if you touch the cambium,
the bark closes up badly. It splits and turns brown.
Then the tapping must be stopped.
There is a product for treating this browning of the bark.
The trees must be tapped
very early in the morning,
so as to harvest as much latex as possible.
If you make the cuts late in the day,
you harvest less latex, one third less.
But you must not tap the trees every day.
Each tree should be tapped on a fixed day.
Each tapper can tap 440 trees.
So he will
have 3 groups of 440 trees,
since he will tap each tree only twice a week.
He will have:
He will stop tapping for two months, in the dry season,
that is, at the time when the tree loses its leaves
and makes new leaves.
When you have worked over the whole length of the tree,
taking away the bark,
that is, after 7 years,
you can begin again,
starting at 1.5 metres from the ground.
You can do this three times.
That means you can harvest latex for 28 years.
After that, it is best to make a new plantation.