Dispersion of magnetic iron oxide powder, γ-Fe2O3 in the mixture of toluene and cyclohexane was studied to decrease the viscosity of the slurry and prepare the stable slurry in the presence of some saturated fatty acids with a straight chain as dispersing agents. The dispersion of γ-Fe2O3 is controlled by the steric hindrance of the dispersing agent adsorbed on it. Therefore, the viscosity and dispersion of the slurry significantly depend on the carbon number and the amount of the fatty acids. Since water content of γ-Fe2O3 greatly influences the control of the viscosity and dispersion degree, low water content is required to get lower viscosity and more stable dispersed state. The four measurements to evaluate slurry flow characteristics, namely viscosity, yield stress, sedimentation volume and particle size measurements, can become a standard method to estimate the degree of flocculation and dispersion of particles in solvents
