Always follow a recommended recipe when water bath canning to ensure it is safe for shelf storage and label then store safely. Foods sealed via hot water bath canning often keep for 12 months or more in a dark, dry, cool place (like your pantry) and are refrigerated once opened.
1. CHOOSE your preserving recipe - i.e. high acid fruits, tomatoes (with bottled lemon juice), or pickles (vinegar with fruit/vegetables) to determine the number of jars you will require. Get jars and new lids out. Jars must be clean and have no cracks or chips. Remember lids are only one-time use, so always use new lids with each batch as the sealing compound inside the lid can wear away and cause seal failure during storage.
2. PLACE rack inside a large pot/canner (or use a round cake rack or clean dishtowel). Place jars (not lids) inside the rack, right way up (jar base should be on rack, on the bottom, with their empty tops facing upwards).
3. FILL pot/canner with water, water should cover jar rims by 1-2 inches (3-5cm). Add 1-2tbsp of white vinegar if you have hard water to prevent streaks on the jars/lids. Place lid onto pot/canner.
4. BOIL jars for 10 minutes to pre-heat while you prepare the jam or other high acid preserve. Start the 10 minute timer once the water inside the pot/canner is boiling steadily. Once the 10 minutes is up, turn the heat off but keep the jars inside the canner until you're ready to fill the hot jars with the hot preserve.
5. WARM up lids by placing into a pot of pre-boiled water (not over heat) and heat for 5-10 minutes while you fill the jars with the prepared preserve.
6. REMOVE hot jars from the pot/canner using jar tongs and place onto a towel-covered surface, the right way up (jar base on the towel).
7. LADLE hot preserve into hot jars to the appropriate headspace (usually 1/4 inch, 1/2 inch or 1 inch, refer to the recipe). The headspace is the distance between the jar rim/top and the surface of the preserve. Use a headspace tool or a clean "kitchen-use-only" plastic ruler to measure headspace accurately.
8. REMOVE air bubbles from the jars using a bubble remover tool or a plastic spatula (or wooden chopstick). Do not use a metal utensil. Remove liquid or add extra liquid if the headspace is not correct.
9. WIPE rims using a damp paper towel (with a little vinegar if rims are sticky).
10. TWIST lids onto jars to fingertip tight, i.e. twist on firmly but not as tightly as possible. Use a hand towel to hold jars firmly while you twist on the lids/bands as the jars will be very hot!
11. LOWER sealed jars carefully onto the pot/canner rack in a single layer. Add a second rack if you are going to double stack in the pot/canner to stop the jars bouncing off one another. The water in the pot/canner should still be 1-2 inches (3-5cm) above the jar lids.
12. CLOSE pot/canner (add lid) and heat over high until the water returns to a boil.
13. PROCESS for the time stated in the recipe, starting the timer once the water returns to a boil and keeping it boiling for the timed period. i.e. Jams/Jellies are all 10 minutes boil to process.
14. TURN off the heat once the time is up, remove canner lid but leave jars inside canner for a further 5 minutes.
15. REMOVE jars from canner using the jar lifter/tongs, and place immediately onto a clean towel-covered bench overnight to seal. Do not tilt, upturn or shake jars. As they cool you will hear a PING! or POP! sound as the air inside the jars cool and shrink, forcing the lid downwards and creating the vacuum seal.
16. LEAVE jars overnight to seal, then check seals the next day (shouldn't flex up and down when pressed). If jars did not seal, re-process with new lids or refrigerate immediately. If jars have sealed go to the next step, removing rings from mason-style (two piece) lids for storage.
17. LABEL AND DATE jars clearly before storing in a cool, dark and dry place for up to 12 months. Some people write the date of when the preserve was made (this is what we do); others write the "best before" date instead. Just remember to use the same system for all of your preserving!

Similar in appearance to a water bath, steam canners preserve high acid preserves via steam. All water bath recipes on our website can be processed via a steam canner (if under 45 minutes). Steam canners use less water than water bath canners so it is quicker to heat too.
Fowlers Vacola, an Australian preserving company, has a slow-boil electric unit, which heats the jars and jar contents up slowly over a longer time period than the water bath canning method described above. Bottles of fruit are placed into the Fowlers Vacola unit, which has cold water in it before it is switched on. This process takes just 60 minutes all you need is the raw fruit and preserving liquid of your choice (other types of high acid preserves are cooled to room temperature before processing in the unit). 
This method is not recommended. 
Open kettle processing involved filling jars and adding the lids, then leaving them to self-seal on the bench (or even upturning the jars once they were on the bench). Open kettle method of preserving does not seal your jars via a water bath.
Why is water bath recommended: the boiling water bath processing results in a much stronger seal, as well as heating through the contents to reduce risk of contamination before and/or during storage, and it is only 10 or so minutes of your time to prevent your hard work being ruined by spoilage (jars can be processing safely whilst cleaning up the kitchen after preparing your preserves).
This method is not recommended. 
Oven canning involved heating or pre-heating jars in the oven. This is no longer recommended because of the consistent results in pasteurisation via a pot of boiling water, which will always occur at the same temperature (for your altitude). Ovens can vary in temperature - many ovens do not heat as low a temperature as the water will go to, resulting in damage to jars over repeated use (i.e. warping jar rims, that can create seal failure when the lid doesn't fit the rim properly), as well as the user hazard of handling hot glass jars from the oven. Glass jars are designed to be heated via moist heat, not dry heat as that that occurs in ovens. Look after your investment in time and money (in purchasing and using jars) for enjoyment for years if not decades of repeated use.
Author: Megan Radaich           
Image credit: Megan Radaich          
Publication: www.foodpreserving.org


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