Curtain stability without curtain contraction is critical for a successful operation in curtain coating, and this can be influenced by the change in particle dynamics and rheological properties of coating colors. In this study, polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) were added to control the rheology of GCC based curtain coating colors. Surface tension was increased slightly with increasing content of cobinder. Shear-thinning of viscosity was more pronounced for the CMC containing GCC coating colors. Complex modulus decreased when small amount of PVA was used as a cobinder, but it increased in other coating colors. Extensional viscosity was increased with increasing of the cobinder content, but CMC was more effective. Results indicate that pigment interaction with PVA is different from that with CMC. Dispersibility of coating colors was improved due to steric stabilization when small amounts of PVA was used, but flocculation occurred by bridging when the amount of PVA was increased. Dispersibility of coating colors was improved when small amount of CMC was added, while flocculation was observed by depletion effect when the concentration of CMC was increased in coating colors. Addition of cobinders at proper levels gave positive effects both in rheological properties and curtain stability. On the other hand, excessive amount of cobinders caused particle flocculation and this resulted in rheological and curtain stablity problems.