In this study, we investigate the physical properties of some pigment based inks that we have formulated in our laboratory. We have used commercially available specially treated surface modified as well as unmodified dry pigments in these formulations. In both cases we have achieved the stable dispersion of pigment particles by appropriate selection of ingredients of compatible physical properties for ink formulation Furthermore, the influence of ink composition and other physical conditions like temperature, solvent mixture, dielectric constants and surface tension were investigated to study their effects on ink stability as well as print quality. We have shown that by controlling the composition, we can easily achieve the desired physical parameters required for proper ink jet printing operation. Based on these results, and considering the interrelationships of different physical parameters, a plausible mechanism of dispersion will be discussed for the stability and shelf life of pigment based inks.