Plastic container having a deep-set invertible base and related methods

A method of processing a plastic container having a longitudinal axis, the method comprising:

• (a) enclosing a softened polymer material within a blow mold defining a mold cavity, the blow mold comprising at least first and second side mold portions and a base mold portion;
• (b) inflating the polymer material within the blow mold to at least partially conform the polymer material to the blow mold cavity;
• and,
• (c) locating the base mold portion with respect to the first and second mold portions to form a transverse pressure panel set within a base portion of the plastic container, wherein the container comprises:
• a finish;
• a sidewall portion extending from the finish and comprising a plurality of ribs;
• a base portion extending from the sidewall portion such that the finish, the sidewall portion and the base portion define an interior volume therein for retaining a liquid commodity, the base portion having a plurality of foot or support portions having a downwardly inclined outer annular wall portion to form a discontinuous or footed contact surface for supporting the container;
• the base portion further including an inner annular wall, the inner annular wall comprising radially displaced regions of lesser and greater angular set, a central push-up portion, and a plurality of webs extending radially along the base portion away from the inner annular wall along a horizontal or transverse axis, substantially perpendicular to the longitudinal axis, each one of the webs having a surface that is radially displaced between the foot or support portions and longitudinally displaced upwardly from the footed contact surface;
• wherein the inner annular wall or pressure panel is moveable between a first position, and a displaced position, wherein the first position is longitudinally away from the finish and the displaced position is longitudinally toward the finish, to reduce volume capacity within the container to provide for a reduction in liquid content volume within the container.