A method for opening a seal including a metal foil and a layer of thermoplastic resin via which the seal is heat-sealed to the rim of a glass jar or equivalent container, the rim having been coated beforehand with a heat-sealing primer, the heat-sealed seal providing hermetic closure of the glass jar or equivalent container, where the initial and final tear forces are not more than 28 N on peeling of the seal at 90° at a speed of 300 mm/min; a glass jar or equivalent container suitable for implementation of this method, where the coating of heat-sealing primer contains an organic and/or inorganic material in which organic and/or inorganic fillers are incorporated; and the application of this method or this glass jar or equivalent container to the packaging of processed food products.