The existence of a thin aqueous film, separating bitumen (a form of heavy oil) from inorganic solids in Athabasca Oil Sands, is analysed based on “first principles”. There is a general consensus in the literature on the hydrophilic character of the solids in oil sands. However, a review of the references cited in support of the solids being encapsulated in thin water envelopes produced a surprising lack of evidence. A theoretical analysis indicates that a water film separating clean, hydrophilic quartz and bitumen is stable under most conditions, and unstable for acidic oil sand ores. The existence of water-wet solids in the Athabasca Oil Sands remains a reasonable yet unproven postulate. It could therefore be dangerous to accept the water-wet solids postulate and then use it to interpret other phenomena.