Manufacturing rubber products requires the use of many additives. Therefore, mixing of the additives with the rubber is a very important step in the processing of rubber. There has been extensive research to try to understand the relationships between the formulation and the properties of the final product. In an industry with more than 100 years' accumulated history and a number of possible combinations of ingredients in the rubber formulation, there is an enormous amount of knowledge. However, this knowledge of exists in fragments scattered as in-house 'know-how' among manufacturers and in the personal experience of the individual operators. This book organises this fragmented knowledge into a coherent whole based on scientific principles. This book is written for students, teachers and those in the rubber industry, who wish to acquire a scientific viewpoint of mixing. Last but not least it is written for the researchers in this field. With the latter in mind, subjects for future research are indicated wherever appropriate. With varied readers in mind, each chapter is written in such a way that it may be read independently from others.