Originally, I had no intention of providing a comprehensive presentation of all textile-processable fiber materials in this manual of textile chemical testing methods. However, as I worked on the project, I increasingly became convinced that such a presentation is not only useful but even necessary if the manual is to fully serve its purpose. In investigations of textile fiber materials, it often becomes apparent that it is important to know the background and general properties of the respective fiber materials, such as their dyeing, processing, and application possibilities. Additionally, knowledge of the scientific fundamentals of the fibers is essential for textile chemical work. Therefore, I have decided to compile all this information in this second volume as the fifth chapter of the overall work.