Abstract Satisfactory dispersion of the carbon black is essential to the production of rubber compounds possessing the maximum possible resistance to wear, tensile strength and abrasion resistance. The methods used to measure/estimate the degree of dispersion are reviewed in this paper. Most current methods are based on some form of microscopy. Light microscopy (at small magnifications) of cryomicrotomed rubber specimens in transmitted light is used to some extent. However, the preparation of the specimen is too time-consuming to warrant the use of the method for routine inspection. This has led to the development of an instrument—the Dispergator—which employs split field microscopy of freshly-cut samples to reduce the total time of testing (including the time required for specimen preparation) to about 1 min.