In an ink-jet printing system consisting of dye-based liquid inks and office copy paper, ink penetration has profound effects on color rendition. In this report we presented methodologies for evaluation of these effects by means of experimental data analysis and simulations. Comparisons between prints with and without ink penetration were made in terms of spectral reflectance values and color representations. They showed dramatic impacts of ink penetration on lightness, color saturation, hue, and color gamut. Advantages and disadvantages of evaluation methods were also discussed.