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Heat Processing

jars heat processing in a pot

Also called ‘water bathing’ or ‘canning’, this process uses heat to stop the growth of bacteria inside a jar. It lengthens the shelf life of your preserves by ensuring your jars or bottles are sealed correctly.
Heat processing time will vary, depending on the product you are making, other preserving agents you have used, and the size of your jars, so always stick to the time indicated on your recipe.


  • A large, deep pot, such as a stock pot
  • Tea towel
  • Room Temperature water
  • Timer
  • Preserving clamps


To heat process, get a large deep pot, such as a stock pot, and place a tea towel on the bottom. Place your jars on top of the tea towel, making sure they are not crammed in, and they aren’t touching the sides of the pot. 

Fill up the pot with enough room temperature water to come at least three-quarters of the way up the side of the jars. Bring to boiling point. Once the water is at boiling point, you can start a timer for the heat processing time indicated on your recipe.

Once the timer is up, your jar lids should be convex or puffed up slightly. Carefully remove your jars with preserving tongs and sit on the counter top to cool down overnight. By morning your jars lids should be concave, indicating they are sealed.