When the sheets are very smooth and are pressed together strongly, I guess they could be viewed somewhat as a unit, so the force to pull them apart would be approximately equal to or less than the atmospheric pressure times the area of the sheets, but definitely not more than, is this correct? Now if you add a few drops of water between the sheets of glass, it becomes significantly harder to pull apart. I can see two reason for this, please tell me if I'm missing anything or if something I say is wrong. 1. Eliminates any air gaps, and so decreases the pressure between the plates of glass 2. Adhesion forces, for smaller distances, the glass might actually pull together because of the adhesion forces.