An example system comprises a water-soluble unit dose article comprising a fibrous non-woven sheet shaped to form a sealed internal compartment and a granular laundry detergent comprised within the internal compartment. The sheet comprises fibres which comprise polyvinyl alcohol polymer. The granular laundry detergent comprises perfume particles. The system also comprises sealing jaws, whereby at least one of the sealing jaws is a heated sealing jaw. A top seal of the internal compartment is sandwiched between the jaws. A first of said jaws comprises a protruding portion along a longitudinal direction of the seal. The protruding portion has a base along a direction perpendicular to the longitudinal direction of the seal. The base has a dimension of more than 3 times and of less than 20 times a thickness of the water-soluble fibrous non-woven sheet.