Storage of sensitive media

In a media storage container having a body portion and a lid, the body portion defining a cavity for the media to be stored and the lid being movable from a position in which a medium to be preserved may be put into or extracted from the body portion to a position in which the body portion and the lid form a closed sealed container about the medium;

• an injection valve enabling the injection of a protective atmosphere from a source outside the container into the interior of the container under pressure;
• and venting means enabling the escape of atmosphere from within the container when the protective atmosphere is injected into the container at a pressure higher than the ambient atmosphere outside the container;
• the improvement comprising co-acting formations on the body portion and lid constituting a cam closure mechanism, which in a first position, maintains the lid with a loose, unsealed fit on the body portion enabling venting of the container while continuing to inject protective atmosphere to allow the inside of the container to be purged, and in a second position provides a camming action of the cam closure mechanism, which seals the lid to the body portion to enable the cavity to be pressurized.