Rubber Tapping & Latex Processing

Tapping

The latex is extracting from rubber tree ( Hevea brasiliensis ) by skillfully slicing a groove into the bark of the tree with a specialty knife.  The trees must be approximately 6 years old and 150mm in diameter in order to be tapped.

The tapping work is done at night or in the early morning when the temperature is lower, so that the latex will drip longer before coagulating.

Ammonia solution are sometimes added to the collection cup to prevent natural coagulation and allow the latex to remain in liquid state.  Liquid latex is used to produce latex concentrate for manufacture of dipped goods or coagulated under clean and controlled conditions.  Natural rubber latex concentrate, is preserved with ammonia solution, contains 60% Dry Rubber Content ( DRC ).

  

Coagulating & Milling 

Latex is a suspension of isoprene, microscopic natural rubber particles in an aqueous medium.  These particles scatter light, making the latex solution appear white and homogeneous like milk.  The surfaces of the latex particles are charged, which creates forces of repulsion between them that keep them from coagulating. In the coagulation process formic acid neutralizes these charges, thereby eliminating the forces of repulsion between the particles. 

The coagulated latex block are then pressed to remove water by passage through rollers.  The last pairs of rollers are grooved and thus produce ribbed sheets.  The ribs increase the surface area and facilitates drying. 

The serum left after latex coagulation is rich in quebrachitol (QCT), and various water-soluble materials such as sugars, lipids, proteins and minerals, which can cause water pollution if the serum is directly discharged into the environment.  

Washing & Drying 

The freshly sheeted rubber are then soaked in running water for a short time after milling to wash off the residual non-rubbers and, to prevent discoloration and mold growth. 

Sheets were hung up to drip off the remaining water for 4 to 6 hours preferably in the shade to drain off the surface moisture and thereby reduce the smoking period. 

 

Smoking 

Dripped sheets which contain about 20% moisture are dried in a smoke house.   Smoking enables the sheets to absorb creosotic and other antiseptic substances which provide a preservative effect and anti-oxidant effect on to the rubber.  Temperature of the smoke house maintained at range between 48-54 °C. 

Generally, smoking could be completed within 4-5 days.