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Published online by Cambridge University Press: 28 July 2016
The first requirement in any manufacturing process is to secure a stable raw material, and to this end scientific control was essential, for it was found that the rubber obtained from trees on the top of a hill differed from the trees in the same field or plantation at the base of the hill. A process of blending was therefore essential.
The pure rubber was rolled and crushed so that it became a “ flannelly ” sheet of crêpe rubber such as is used on tennis shoes, etc., but in this form the rubber becomes sticky when heated. Filling agents are therefore added, and colouring materials to give the red tint for inner tubes and grey for outer covers.