Apparatus (20,120) for forming a heated glass sheet G is disclosed as including a vacuum mold (22,22a,122,122a) having a full surface (24,24a,124,124a) against which a peripheral mold (26,26a,126,126a) presses the glass sheet periphery and with which at least one vacuum reservoir (32,33) is communicated within the interior of the sealed glass sheet periphery to form the glass sheet to the shape of the vacuum mold surface. Valving (38) of a vacuum system (28) is preferably operable to provide the vacuum impulse in two stages with an initial limited extent of vacuum and a subsequent greater extent of vacuum by communication first with one vacuum reservoir (32) and subsequently with another vacuum reservoir (33). Different embodiments of the vacuum mold have the vacuum mold surface facing upwardly and downwardly with convex and concave shapes. Glass sheet shapes including straight line elements such as cylindrical and conical bends as well as shapes including curvatures in transverse directions and inverse curvatures can be effectively provided by this vacuum impulse forming.