If you are at an altitude of 1,000 feet or more, add one minute to the sterilizing time. Wash and rinse all canning lids and bands. Prepare the lids as directed by the manufacturer. Sealing the Containers All jams, jellies, and other fruit spreads must be processed in a boiling water bath to prevent mold growth. Paraffin is no longer recommended as a method for sealing jams and jellies.
Air can seep in around the edges and cause spoilage and mold.
Wipe the jar rim and close with a prepared canning lid and screw band. Place on a rack in a canner filled with boiling water. The water should cover the jars by at least one inch. Cover the canner. Bring the water back to a boil and boil gently for 5 minutes.