Color pigmented inks have the advantage in durability and are used in many printing industries. But for ink jet inks, they are used limitedly because of the necessity of specific combination with the media. Actually the color pigmented ink jet inks were first developed for wide format printer with the special coated paper. Remove of the restriction of media is needed to expand the possibility of color pigmented ink jet inks. For this expansion, encapsulated pigment had been proposed having durability independent of the media.In this paper, pigment dispersions with different amount of desorbed polymer are investigated to maximize the optical density on the plain paper. The amount of the desorbed polymer in the ink is found important to improve the print quality on the plain paper.