In a standard anionic coating, there is some penetration of the coating into the pore structure of the paper generating a mechanical interlocking of the coating layer and the paper [29]. However, in the layer-by-layer process, the second layer cannot penetrate the underlying coating, and hence, the coating strength relies primarily on the adhesive forces between the two coatings. The adhesion at the layer-layer interface due to electro-attractive forces is weaker compared to a mechanical interlocking mechanism that happens in the pores of paper due to penetration of the coating components. This leads to coating failure at the interface between two coating layers. This result also supports our findings for our one-layer system; the increased strength in all-cationic coat- ing arises from the lack of migration of the cationic SB latex into the paper which, in turn, does not deplete the latex from the middle of the coating layer. The wet-on-wet or wet-on- dry deposition for both first anionic or first cationic coating layer systems did not show any difference in the pick values for the two-layer coatings. This shows the lack of migration between the two coating layers regardless of the nature of the first layer and wet-on-wet or wet-on-dry approach.