A bag for containing a flowable product comprises a plurality of panels hingedly coupled along fold lines, an opening at one end of the bag, and a flap hingedly coupled to one panel along a fold line for overlapping an opposite panel and closing the opening. An adhesive layer extends across the entire width of the flap to seal the flap to the opposite panel. The adhesive layer seal has a reduced bonding strength adjacent one end of the flap to facilitate opening of the flap at the reduced bond strength section. The reduced bonding strength is provided by an adhesive coating comprising kaolin clay. This arrangement is particularly useful in heavy weight bags which are sealed by a hot melt adhesive.