A method of forming a container including the steps of: providing a sheet material defining a peripheral wall structure bounding a receptacle with an open end, and a closure portion having gable panels and a plurality of fins for closing the open end of the receptacle; reconfiguring the closure portion to place the closure portion in a closed state wherein the plurality of fins are in overlying relationship and the gable panels reside between the fins and the peripheral wall structure; effecting a seal between a plurality of the fins using a first sealing pattern; and after effecting the seal using the first sealing pattern effecting a seal between a plurality of the fins using a second sealing pattern.