The structure and composition of sapphire bicrystal boundaries produced by liquid-phase sintering depended on the crystallographic misorientation of the crystals across the boundary and on the orientation of the boundary. Basal twist boundaries of 15degrees or 30degrees were not wetted by glass, but contained significant amounts of Ca and Si at the boundary. For tilt boundaries of 7degrees or 12degrees, the glass wetted segments of boundaries that contained the basal plane of either crystal. Boundary segments with orientations of 40degrees or more from the basal plane, however, were dewetted (i.e., "dry"). Boundary segments oriented less than similar to40degrees from the basal orientation were partially wetted, consisting of segments of wetted and dry grain boundaries. For the 12degrees tilt boundary, Ca and Si could be detected on portions of the boundary that contained no glass. For bicrystal boundaries having tilts of less than or equal to4degrees, dewetting occurred for all observed boundary orientations. Basal-oriented segments in these small angle tilt boundaries contained noticeable concentrations of adsorbed Ca and Si, while nonbasal segments were apparently free of Ca and Si. Most results could be explained based on a combined Wulff plot construction, which predicts partially wetted grain boundaries and "missing" angles for unwetted grain boundaries. Results that could not be explained by the construction included growth step ledges bounded by nonequilibrium facet planes.