Sept. 190(5. J 



•211 



Saps and Exudations. 



MANUFACTURE OP RUBBER. 



16. Preliminary Processes. — The various processes through which raw 

 rubber passes in conversion to rubber goods were, as a whole, very freely shown 

 to me by the British rubber manufacturers. Introductions to the leading firms 

 from the War Office and Admiralty, who are large consumers of rubber goods, were 

 obtained through the Colonial Office, and these, together with sundry personal and 

 private introductions, proved to be all that was necessary, and I met with great 

 consideration, kindness and courtesy from all with whom I came into contact. In a 

 few cases there were special and particular processes which were guarded as trade 

 secrets, but this tendency to secrecy was in inverse proportion to the size and 

 importance of the works. The greatest interest was shown in plantation rubber 

 and the prospect of a future easing of the rubber market by supplies from the 

 East, and the manufacturers realise that there can be no antagonism between them 

 and the planters, and appreciate the efforts being made to bring the producer and 

 consumer into closer touch. 



17. The raw rubber used is of all kinds and qualities, from clean pure fine 

 Para to the lowest grades of African rubbers, which are sticky, black, full of 

 wood, stones and dirt, and all possible adulterations. Pine Para is delivered in 

 balls weighing from five or six to a hundred pounds ; when cut open the mass is 

 seen to be made up of concentric shells from | to i inch in thickness, the rubber is 

 grey and wet and the successive laminae are marked by dark surfaces, showing 

 the stages of successive smoking and accumulation of the rubber into balls. This 

 rubber is never dry, but contains water— the amount usually being about 15 per 

 cent., bint varying from 10 to 20 per cent., and the loss of weight of fine Para in 

 washing and drying is due to this water contained in it. In the best qualities there 

 is little or no mechanical impurity, at most a little surface dirt and grit- 



WASHING RAW RUBBER. 



18. The first thing to be done is to cut these large balls open and reduce 

 the largest masses to blocks of five to ten pounds in weight. The rubber is then 

 softened by boiling in water, this is done to enable the washing machines to deal 

 with the lumps. 



The rubber is then broken and washed on machines which are simple in 

 construction and action, and exactly similar in essentials to the rubber-washing 

 machines in use in the Malay Peninsula on plantations. 



Each machine consists of a pair of steel rollers with roughened faces, 

 revolving at different speeds on horizontal axes, the faces of the rollers being in 

 contact or slightly separated from one another. The rollers are from one to 

 two feet in length, and usually one foot in diameter. The surfaces are roughened 

 with grooves cut spirally, or diamond shaped, and of different angles and depths 

 according to the nature of the work. Cold water is always playing over the surfaces 

 of the rollers in use, and it is directed usually above the rollers on to the rubber in 

 the hopper, but in some cases at the sides, with the object of washing the dirt 

 away from the rubber as the rubber emerges from between the rollers. The rubber 

 usually goes through two sets of rolls, the first two break down the big lumps 

 and roughly sheet the rubber, the second pair of rolls is smoother and in closer 

 contact, and the final washing and working into a fine-grain uniform sheet is 

 performed on these. In preparing rubber for the very finest work, such as cut 

 sheet, a third set of rollers with smooth chilled steel surfaces is used. The object 

 of these is to crush any particles of sand or grit which might otherwise be left in 

 the rubber and damage the knives and spoil the sheet rubber when being cut 

 The rollers are always provided with metallic guides to keep the rubber away from 



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