CHAPTER XII. 



DRYING AND PACKING RUBBER FOR EXPORT. 

 DRYING THE RUBBER. 



WHATEVER system of preparing the rubber be employed it is 

 essential to thoroughly dry it previous to shipment. In the 

 moisture laden atmosphere of the tropics this naturally takes 

 considerable time unless artificial aid be called in. It has already 

 been shown that the presence of moisture in the rubber encour- 

 ages putrefaction and " tackiness." The sooner it is expelled 

 from the rubber the better ; still, high temperatures are not 

 advisable, as unvulcanised rubber is very sensitive to high 

 temperatures, which cause softening, a loss of nerve, and 

 bubbles to form on the surface of the rubber, which spoil its 

 appearance. Para rubber will bear more exposure to heat with- 

 out detrimental effects than those grades which contain a larger 

 percentage of resinous and oily matters, but it is considered that 

 a higher temperature than 110 Fahr. is liable to prejudice it. 

 The commonest method in vogue is that of passing over the 

 rubber a current of hot dry air. 



Drying houses similar to those employed in the manufacture 

 of cocoa have been advantageously employed on some estates. 

 In these hot air is drawn from a furnace situated at one end of 

 the building through iron ducts by means of fans fixed at the 

 opposite end of the building. A fairly constant temperature can 

 be obtained, and in the case of cocoa drying it is often maintained 

 at 110 Fahr. The rubber in these is usually placed on shelves 

 made of wire netting. 



Drying houses on the same principle as flue-curing tobacco 

 barns could also be satisfactorily employed, providing sufficient 

 ventilation were supplied. In these the furnace is built of 

 bricks. It is placed outside the building and sunk in the ground 

 in such a manner that the flue enters the building just above the 

 floor level, 



