Nano and microfibrillated cellulose (NFC and MFC, respectively, collectively termed MNFC) is known to interact strongly with water, related to its high polarity and surface area. The swelling behaviour acts to form a gel with high water retention properties. The observation that nanocellulose could possibly be used in paper or other coating formulations, as a co-binder, for example, raises a question about the possible effects it could have on coating pore structure. In this study, we analyse the pore structure of pigmented coatings, liquid absorption and permeability, in respect to the influence of partially substituting traditional co-binder carboxymethyl cellulose with MNFC. The contrast between polar water and non-polar liquid, such as alkane, is used to probe the water interactive and extractable in-coating (internal) gel-formation properties of the nanocellulosic materials. These contrasting liquids are important in many processes, such as offset printing, but also in respect to exposure of coatings in general to environmental factors in application. Results show that permeability to liquid water is dramatically reduced when nanocellulosic material is present, though water can permeate by diffusion through the nanocellulose gel network. Long timescale exposure to water during absorption leads to extraction of any soluble salts remaining after the chemical treatment of the fibrillar material during production. Inert alkane, on the other hand, can absorb and permeate freely without interactive hindrance from the nanocellulose, with no extractive effect. Such a construct could in principle be considered for use as an oil-water differential membrane or for slow release concepts in aqueous systems by loading soluble deliverable materials within the nanocellulosic gel.