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University of Horticultural Sciences, Bagalkot

Kittur Rani Channamma College of Horticulture,Arabhavi

Harvesting & Processing of Rubber

By, Ravi. J. Pujari UHS11PGM142 Dept. Of. PMA

Presentation on

Harvesting in rubber is known as tapping.Tapping is the periodical removal of thin slices of bark to extract rubber latex. It is the process of controlled wounding with the shaving of bark removed. The latex vessels are found in the inner layer of soft bast of the bark. The latex vessels are concentrated in in the soft bast arranged in a series of concentric rings of inter connecting vessels. Tapping is done by skilled men.

Tapping

Tapping

Types of Tapping Knives

While tapping, the cambium should not be damaged as otherwise callus formation will take place causing swellings. The rubber trees attain tappable stage in about seven years. The best season for tapping is March or September depending upon girth of the tree. The latex vessels in the bark flow at an angle of 320 to the right and therefore a cut at higher level from the left to right has to be carried to facilitate opening of a large number of latex vessels. Tapping is done in the early morning, late tapping will cause reduction in the flow of latex.

Tapping Systems & Intensity

Sl.No Tapping Sytems Intensity Remarks

1 s2d2- Half spiral, tapping alternate days for 6 months

and rest for 3 months.100 %

Recommended for budded plants.

2 s2 d3- Half spiral, tapping at every three day for 6 months

and rest for 3 months.67 %

Recommended for clonal plants.

3 s2 d1 – Half spiral daily tapping. 200 %

Followed by small growers but it favours brown blast incidence

and causes early deterioration of trees.

In South India, rubber trees shed their leaves during December- January & immediately again they put forth the new leaves and flowering.

During this period the trees are given rest since the yield of the rubber will be poor if tapped. The yield of the rubber steeply increases year by year and the peak is reached at 14-18 years after planting.

Then it slowly declines . After 40 years it may

not be economical to maintain the trees.

The latex yield will vary with the clone, age of

trees, fertility of soil, climatic conditions and

skill of the tapper.

Types of Tapping

1. Puncture tapping

Puncture tapping or micro tapping is basically an

incision method of tapping. Micro tapping is done with

a small needle on a vertical band of stimulated bark.

The length of the strip is usually limited to 60 cm and

the number of punctures made may be 4 or 5.

Puncture tapping

2. Slaughter tapping

Intensive tapping prior to felling of the old trees is

called slaughter tapping. It is often done at higher

levels sometimes even on branches with the help of

ladders and not on the usual renewed bark levels.

As the objective of slaughter tapping is to extract as

much as latex as possible from the available bark, no

consideration is given to the technique, intensity or

standard of tapping.

Slaughter tapping

Rain guarding By fixing a polythene rain guard to the trunk of the tree above the

tapping panel, tapping can be carried out during rainy season also

Growth regulators like 2,4 dichloro phenoxy acetic acid and 2,4,5

tri-chloro phenoxy acetic acid are applied through vegetables oils

these are applied in a broad band round the trunk under the

tapping cut of the rubber tree many proprietory products like

stimulex, flow more, ready rub containing the above growth

regulators are available in the market as rubber stimulant

Rain guarding

Composition of Latex

Contents Percentage(%)

Rubber 30-40

Protein 2-2.5

Resin 1-2

Sugar 1-1.5

Water 55-60

Generally used anti-coagulants

• Ammonia, Sodium sulphate & Fomalin.

• Ammonia 0.7% is the most popular latex

preservative.

Yield of Rubber

• In South India, the annual yield of rubber is about 375 kg/ha from seedlings where as budded plantations yield about 900-1000 kg /ha

Processing of Rubber

• The latex that flows out from the rubber trees on

tapping is channeled into a container, generally

coconut shell cups then is transferred to clean buckets,

two to three hours after tapping.

• The latex which gets dried up on tapping panel (tree

lace) and the collection cups shell scrap also form a

part of the crop and are collected by the tapper in

baskets just prior to tapping.

• The latex split including over flown on the

ground (earth scrap), when gets dried up, is

also collected once in a month. Normally

10-20 % of the total crop constitute the

tree lace, shell scrap and earth scrap.

Rubber can be processed and marketed as

1. Preserved latex concentrates.

2. Dried sheet rubber.

3. Dry crepe rubber

Preserved latex concentrates

• The latex is collected in the storage tank, from there

it is brought to a centrifuge machine, rotating at

1400 rpm. Due to centrifugal action, liquid portion

comes out.

• The upper layer and the concentrated latex, is

collected and brought to bulking tank and mixed

with chemical and packed in drums. 60% rubber is

present in it.

• Skim latex is taken to another tank then

sulphuric acid is added which gets coagulated

& it is milled to get skim crepe. It is of poor

quality while the concentrated latex fetches

very higher price.

Dried sheet rubber

• Anti-coagulants (solutions of ammonia, Formalin or sodium sulphite are added to the cups to prevent the coagulation of latex before it reaches the factory.

• The latex so collected is then bulcked and then strained to remove the impurities. It is then diluted to a standard consistency of 12-15% rubber.

• Special hydrometers like mrtrolac, latex meter are employed to measure the percentage of rubber.

• After dilution, the latex is strained through a 60 mesh screen for the second time.

• Then it is poured into the special coagulating tanks or aluminium pans which is divided into many compartments by thin aluminium sheets and acetic acid or formic acid is used for coagulation.

• Slow coagulation produces a soft rubber which is easy to work on the rollers.

• The acid is to be added quickly and mixed thoroughly with the latex. Froth formed is removed to avoid formation of bubbles on the surface of rubber sheets.

Dried sheet rubber

Rubber rolling

• After coagulatuion, rubber sheets are repeatedly washed

several times with changes of water & passed through hand

or power operated rollers. In the roller excess water &

dissolved impurities are pressed & squeezed out

• The surface of the rollers may be either smooth, or grooved

or zig zag or straight or diamond pattern, its impression is

normally left on the surface of the sheets when they come

out of the press

• These sheets are hung in shade for 2 or 3 hrs, for dripping in

a dust free place

• They are taken to smoke houses for thorough drying. Smoking

of rubber sheet is done to dry the sheets properly

• To avoid formation of blisters. In the smoke house, the sheets

are smoked at a low temperature of 48-500 C with fairly high

humidity during the first day subsequently during second to

fourth day the temperature being 680 C with low RH

• They are taken out, graded & packed. Such products are known

as smoked sheets or dry ribbed sheet rubber

Various grades of rubber sheets are

• RMA IX, RMA-1, RMA-2, RMA-3, RMA-4, RMA-5.

• High grade rubber sheets are clear, free from blisters, translucent & of a golden brown colour & fetch a better price.

Dry crepe rubber

• When coagulum from latex or any form of field coagulum after necessary preliminary treatments is passed through a set of creeping machines to get crinkly, lace like rubber called crepe rubber after drying.

• Various grades of crepe rubbers are • EPC Super 1X, EPC 1X, EPC 2X & EPC 3X.

Dry crepe rubber

References

• Shanmugavelu, K.G., Kumar, N. & Peter, K.V., 2002, Production Technology of Spices and Plantation Crops.

• Internet

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