it takes slightly longer than the other ways but starts the process about 30 minutes before your preserves are ready to pot and you will not even notice the time.
heat the oven to 130c/ 275f do not be tempted to heat the oven any higher, or you may risk the glass breaking.
lay a double layer of newspaper on each oven shelf but not the floor of the oven. if you are using a gas oven, make sure your newspaper is well away from any flame. if it is on a middle shelf, you will be fine.
arrange the jars on the oven shelf, making sure the jars are not touching each 