Sterilising is an essential first step whenever you preserve in Kilner jars or bottles. Kilner explains that it removes bacteria, yeasts, fungi and other organisms from the jar, so your food stays fresh once sealed. Here is Kilner's own recommended method, along with its answers to the most common questions. Shop jars in our Kilner collection.
Important: Kilner warns never to sterilise its jars or bottles by pouring boiling water into them.
Kilner's water bath method
- Check for damage. Inspect every jar or bottle for cracks, chips or breaks, and throw away any that are damaged.
- Time it right. Kilner advises sterilising only a short time before you fill, so the jars are still warm.
- Wash. Wash the jars in warm soapy water and leave them to dry.
- Prepare the water bath. Remove the lids or rubber seals and set them aside. Place a heat-resistant plate upside down in the bottom of a large pan such as the Kilner 8 litre Jam Pan, then stand the jars on it.
- Boil the jars. Fill the pan with cold water until the jars are covered. Bring it to the boil and hold at the boil for 10 minutes. Turn off the heat and cover the pan to keep the jars warm until you are ready to fill them.
- Sterilise the lids and seals. Put the sealing lids or rubber seals in a small pan with about 10cm (4 inches) of cold water. Heat and simmer at 82°C for 10 minutes, then turn off the heat and cover the pan until you are ready to seal.
- Dry. Lift the jars, seals and lids out with jar tongs and leave them to dry on a clean cloth. They are now ready to fill.
Always take care handling hot jars and lids. Kilner recommends jar tongs or oven gloves.
Sterilising FAQ
Can I sterilise Kilner jars by pouring boiling water into them?
No. Kilner says never to pour boiling water into its jars or bottles. Always heat the water with the jars in it, as described above.
Can I sterilise Kilner jars in the oven?
Kilner advises against it. It says ovens can harbour bacteria from food stuck inside, and a fan-forced oven will circulate that bacteria.
Can I sterilise Kilner jars in the microwave?
Kilner doesn't recommend it. It considers the microwave unreliable for sterilising because its internal pressure is difficult to measure.
Can I sterilise Kilner jars in the dishwasher?
Yes, Kilner says you can. Remove the rubber seals and lids, place the jars on the top rack and run a hot wash using only hot water, with no detergent or cleaning products. Time it to finish when you are ready to fill. Kilner still recommends the water bath method, because you can't be sure how clean the dishwasher itself is.
Do I need to sterilise brand new jars?
Yes. Kilner says even new, packaged jars need sterilising before you preserve in them.
What happens if I don't sterilise?
Kilner says sterilising removes any bacteria that may be in the jar, even when it looks clean. Skipping it risks your preserves spoiling, and sterilising also extends their shelf life.
Next steps
Once your jars are sterilised, follow our Preserving with Kilner Jars guide to fill, seal and store them. If your seals are worn, our replacement seals guide shows which ones fit your jars. For an overview of the range, see the Kilner Jar Guide.