The application performance of carbon black depends on its fundamental properties and the degree of dispersion achieved. The most important physical and chemical properties include particle size, porosity, structure, and surface chemistry. The degree of dispersion in any matrix critically depends on the mixing equipment used, the formulation (including choice of dispersant), and the physical form.

Particle size is the primary factor influencing color. Particle size can be measured by electron microscopy (EM). The average particle size is determined from the external specific surface area (STSA) measured according to ASTM D3849-14. Smaller particle size results in larger surface area and higher tinting strength. Larger surface area generally means higher jetness, higher electrical conductivity, better weather resistance, and higher viscosity, but requires higher dispersion energy.

Structure is a parameter that measures the size of three-dimensional aggregates formed by fused carbon black particles. High-structure carbon black provides higher viscosity, better electrical conductivity, and easier dispersion. Carbon black structure (aggregate size) can be characterized by electron microscopy image analysis, oil absorption number (OAN), or compressed volume analysis.

Porosity is characterized by comparing the difference between the measured external surface area (STSA) and total surface area (BET NSA) of carbon black. Conductive carbon blacks generally have higher porosity.

Surface chemistry, in the context of carbon black, generally refers to the oxygen-containing chemical groups on the carbon black surface. Surface oxidation treatment improves the wettability, dispersibility, rheology, and overall performance of pigments in specific systems. In other cases, surface oxidation treatment increases electrical resistance and makes carbon black more hydrophilic. The degree of surface oxidation is determined by measuring the "volatile" content of carbon black. Carbon blacks with high volatility have lower pH values.

Physical form is an important consideration for selecting dispersion equipment matched to the specific carbon black being dispersed. Powdered carbon black is recommended for low-shear dispersion equipment and three-roll mills. Beaded carbon black is recommended for internal mixers, bead mills, and other high-energy equipment. Beaded carbon black produces less dust, has higher bulk density, and can be processed in larger batches; powdered carbon black offers better dispersibility.