Predicting how light propagates through a stack of ink layers for spectral reproduction is a challenge only optical models can face. In particular, the four-flux model offers directional information about the part of light specularly reflected and transmitted and the part of light scattered in other directions. The surface roughness influences strongly the ratios of collimated and diffused light. In this paper, we describe how a radiative transfer four-flux matrix model can account for rough interfaces and show how roughness impacts the measured components of the reflectance and the transmittance of stacks of ink printed with different textures. The measurements are then compared to computations of the model with colorimetric and spectral metrics. Results are encouraging, considering that the predictions are made without any measurements directly inputted into the model, with the median color difference mostly below 2 ΔE₉₄ units for total reflectance and transmittance whatever the roughness.