You can now sterilise the jar. If it has a rubber seal, remove it. Set your oven to 140°C/275°F/gas mark 1, wash your jar in hot soapy water, place it upside down on a baking tray and put it in the oven for around 10 minutes, before removing it to cool. Don’t touch the inside of the jar before you make your gin. Boil the rubber seal for 10 minutes in a saucepan of water.