all the mason jar does is slow up the drying process so it can cure properly. then they're great for storage...

and yes, starting the cure too soon will most likely produce mold so it's very important you watch your stash closely and follow the instructions if you're going to cure your harvest...many don't and just let it dry until it's smokable...not good, imnsho. curing reduces most of the chlorophyl (sp?) which gives pot that 'green' flavor, reduces the harshness and aids in long-term storage. plan on spending 3-4 weeks doing a cure but you can still keep out a little for use while watching em dry...