The extensive use of polyvinyl pyrrolidone (PVP) as an ink acceptor material derives from two concurrent attributes: the propensity to bind anionic dyes and the ability to rapidly absorb the liquid vehicle.1 Recognizing that polymer microstructure and morphology regulates ink permeability, we utilize a diverse array of PVP copolymers in order to systematically investigate the simultaneous impact of comonomer composition on ink penetration and dye immobilization. On the basis of the offset (dry time) protocol and corresponding optical density measurements, we elucidate the fundamental mechanisms underlying the chromatographic separation of ink jet dyes from aqueous solvents during the diffusion of picoliter ink drops into hygroscopic films of various PVP copolymers.