228 RUBBER AND 



Manufacture of Various Articles. 



A large variety of articles are made directly from 

 sheet rubber. The highest class of cut sheet rubber is 

 used in the manufacture of such articles as tobacco 

 pouches. Permanent joints can be made by simply 

 pressing together the cleanly cut edges of the sheet. 

 In order to prevent adhesion at other points, French 

 chalk is dusted over the surface. If lower grade sheet 

 is used, it may be necessary to moisten the edges with 

 solvent or with rubber solution in order to make a 

 permanent joint. 



Block rubber is reconstructed from sheet for the 

 manufacture of such articles as railway buffers. The 

 sheet is rolled up into a cylinder and firmly pressed 

 together. Greater strength is thus obtained than by 

 simply blocking the mixed rubber. The nature of the 

 increased strength may be understood from the analogy 

 of heavy guns wound from wire, which are much 

 stronger than the old fashioned guns cast in one 

 piece. 



Large tubes, such as the inner tubes for motor tyres, 

 are made by rolling the sheet rubber round an internal 

 mould known as a mandrel. The edges of the sheet 

 are joined together with solution. The ends of the tube 

 are cemented up after vulcanisation and removal from 

 the mandrel. The removal of the tube is effected by 

 the aid of compressed air. Smaller tubes of a simple 



