Actually if the jar isn't jostled doesn't matter if the ring is a bit loose.
CO2 is heavier and displaces lighter gases, ie oxygen. Hence the roasted
beans stay surrounded by the inert CO2 rather than oxidizing from oxygen.
Theoretically the dome could even be taken off, but that would require zero
air movement in the room.
Kona Konnaisseur miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.