This paper represents the third of a three-part series in which multi-component fiber blending was analyzed using an integrated approach. The essence of this approach is that the phenomenon of fiber blending should be viewed on the basis of four basic modes of blending: structural blending, attributive blending, interactive blending, and appearance blending. In this part of the study, the focus is on interactive blending. A modified rotor ring system is used in which the torque associated with opening and blending of a certain mass of fibers is monitored throughout its complete run. Blends of different cotton fiber types and blends of polyester and cotton fibers are evaluated using a number of analytical methods such as the torque profile during opening and blending, the blend profile of torque parameters, and the progressive change resulting from consecutive opening and blending. The results of this study revealed that when cotton fibers of different types are blended together, fiber length and fiber fineness can influence interactive blending in such a way that a great deal of the initial mechanical work done is consumed in opening and blending the longer and finer component in the blend. Large difference in fiber length and fiber fineness can result in a nonadditive and nonlinear maximum torque associated with blending. When cotton fibers are blended with polyester fibers, surface incompatibility becomes a more serious issue than fiber dimensional characteristics. In this regard, a possible failure of fiber cluster breakdown may occur, leading to nonlinear and nonadditive interactive blending. The results also reveal that the propensity to opening of different fiber types may follow different trends in consecutive processing.In Part I [1] of this study, we introduced different analytical aspects that can collectively reveal the full nature of fiber blending. In Part II of this study [3], we discussed structural and attributive modes of blending using blends of different cotton fiber types and blends of polyester and cotton fibers. In this Part of the study, we shift our attention to interactive blending. This implies the interaction between fibers within a fiber component and between different fiber components during the blending process. Understanding the nature of this interaction can result in selecting appropriate fiber types and fiber attributes for a particular process and in optimizing machine settings for particular blends. In addition, interactive blending is often associated with many technological problems including: rough fiber flow, machine clogging, and breakage of fiber strands. These problems can have a great impact on the consistency and quality of blended end products [6,8,10].Among all modes of fiber blending, interactive blending is the least understood. This is due to its complex nature and the dynamic changes encountered when fibers of different types interact together during processing. In practice, this mode of blending is typically evaluated through experimental trials involving actual...