@marjon @defred There're also special glasses or lids with a valve that release the pressure, This wasn't one of them. In the past I build my own gas valve with a little plastic bag with water (make sure no air left inside), with which I covered the kimchi glas. So the CO2 could escape but no Oxygen could get in. It's a bit messy and with a lot of gas buildup it can spill, so put something like a plate under it, but it works