Hot fill mold shell assembly with reduced heat transfer

A hot fill hot fill mold assembly has two mold half shells and two mold half carriers for supporting the mold half shells. The shells each have an inner wall that defines the shape of at least a portion of the container to be formed. Each shell has outer wall surface portions and a plurality of spaced apart slotted grooves extending between the outer wall surface portions that define open air spaces recessed from the outer wall portions. The mold half carriers have a carrier inner wall that overlays in contacting and thermal conducting relation the outer wall surface portions of a corresponding one of the mold half shells and overlays the spaced apart slotted grooves to create thermal buffering open air pockets between the mold half shells and the mold half carriers so as to reduce the thermal conduction away from the mold face and improve hot fill container formation.