ABSTRACT
The principal raw materials used, apart from the rubber itself, which forms about half the total weight of the tyre, are cotton or rayon, carbon black, sulphur, zinc oxide and a large number of other chemicals, added to give the rubber special qualities for the particular job it has to perform when in service. The raw rubber is masticated and made plastic in a steam-heated roller mill, and various other filling and colouring materials are added gradually as the kneading process goes on. Finally sulphur is added and the mixture rolled out in the form of rough sheets which are cut into pieces ready for loading in the moulds. The preliminary processes of making rubber sheeting are similar except that no sulphur is added to the mixture of uncured rubber. Linoleum is made by pressing a plastic mixture of oxidized linseed oil and other ingredients in a smooth sheet on to a backing of jute canvas.
