The plantation rubber tree is a factory, specifically designed to produce as much latex as possible. To this end it can be considered to consist of three parts:

After a short time growing in pots the three part trees are planted out in a nursery before finally being transplanted into the plantation.

They are allowed to grow for about six years and then it becomes cost effective to tap them.

Tapping is the name given to the removing of a thin sliver of bark so that the latex can flow rather like blood from a graze on the skin. The orange panel in the picture opposite is the ‘tapping panel’ which slowly moves down the tree as successive tappings are carried out.

Tapping takes place in the early morning, before the real heat of the day (so it is dark!).

It usually takes place every day or every other day.

 

 

For a few hours the latex flows from the ‘grazed’ trunk, runs down the gradient of the sloping panel to a vertical cut and then to a metal spike which sticks out of the tree and allows the latex to drip into the collecting cup.

Eventually the flow stops as the wound heals and the flow stops.

Later that day the tapper goes round his/her allocated trees to collect the latex in a pail.

 

 

 

 

 

 

The pails are then filtered and bulked into drums after which they are taken by lorry to the processing centre.

At this point the latex can be treated in several ways:

The first process described is the making of ‘ribbed smoked sheet’ (RSS) which was very popular until the mid 1960’s but is still used to a lesser extent today.

On a small scale, at the smallholders or a co-operative, the latex is coagulated by the addition of a little acid. The effect is similar to curdling milk. The coagulum is removed.........

.........and passed through a mill which squeezes most of the water out of it. The rollers of the mills are patterned with ribs which impart their imprint into the sheet hence its name - ribbed.

The ribbed sheets are cut to size and hung out on racks to dry before being wheeled into a smoke house where the sheets are smoked for several hours.

When they are removed they are dry and a deep golden-brown colour.

They are examined by holding them up to the light and graded on the levels of dirt seen. After which they are wrapped together to form bales and shipped in that format.

 

 

 

In another process, the latex is bulked in massive storage tanks from which it can be run into large drums (45gal) for sale and export or prevulcanized before being drummed and sold.

The small scale preparation of ribbed smoked sheet can be scaled up using large tanks with baffles to separate the coagulum.........

or the coagulum.........

can be passed through a series of rollers to give a sheet.

If a small amount of castor oil is dribbled onto the rubber whilst it is being milled the sheet breaks up into a crumb.........

which can be dried in big bins ready for weighing and bagging as shown below.

If the latex is left in the collecting cup overnight it will coagulate by itself and in any plantation there is always scrap dry rubber to be found. This is cleaned up and sold – mostly going into tyres.

 

The rubber is loaded onto a machine which crumbs it whilst washing it with large quantities of water.

The resulting crumb (much darker that that obtained from latex is binned.......

and dried.........

Weighed to give uniformly sized bales of 25kg.........

Compressed........

Wrapped.........

and placed into 1.2 ton pallets ready for shipment.

These rubbers are graded by chemical tests, rather than visual inspection and are sold as ‘technically specified rubbers ‘ (TSR).