An apparatus for vacuum-sealing a lid onto a jar includes a cap skirt joined to a cap. The cap and cap skirt are formed with internal threads for engaging corresponding external threads on the jar. A lid for the jar placed against the lid press will be drawn against the rim of the jar after air is pumped out of the jar through the cap. An airtight seal is established between the lid and the rim of the jar when air at normal atmospheric pressure enters the vacuum port, the pressure difference between the outside and inside of the jar forcing the lid onto the jar rim and sealing the jar. A prying plate positioned on the top of the cap permits removal of the lid without deforming the lid beyond its elastic limit, enabling lids to be removed and re-sealed against the jar.