Boiling-water canners are made of aluminum or porcelain-covered steel. They have fitted lids and removable perforated racks. When choosing a boiling-water canner to purchase make sure that it is deep enough so that at least one inch of briskly boiling water will be over the tops of jars during processing. *Note: if you are working with an electric range you must purchase a boiling-water canner with a flat bottom. Not all boiling-water canners have flat bottoms. Also make sure that the canner is no more than 4 inches wider in diameter than the electric element on which it is heated. If you have a gas burner you can use either a ridged bottom or a flat bottom.
How to Use a Boiling-water Canner
Step 1) Prepare the canner by filling the canner halfway with clean water- the approximate amount of water needed for a load of pint jars. Adjust the amount of water depending on the size and number of jars so that the water level will be 1-2 inches over the top of the filled jars.
Step 2) Preheat water to 140°F for raw-packed food and 180°F for hot-packed foods. While the water is preheating, prepare the food.
Step 3) Load the filled jars into the canner rack and use the handles to gently lower the rack into the water. You could also fill the canner with the rack in the bottom by placing one jar into the rack at a time using the jar lifter. To properly use a jar lifter make sure that it is securely positioned below the screw band of the lid. Keep the jar upright at all times.
Step 4) If needed, add more boiling water so that the water level is at least 1 inch above the jar tops. If processing for longer than 30 minutes the water level should be at least 2 inches above the tops of the jars.
Step 5) Turn the heat to its highest position, place the lid on the canner, and heat the water until the canner reaches a rolling boil. Set a timer for the total minutes required for processing the food (reference these printable charts if your recipe does not indicate pressure and time).
Step 6) While the canner is covered, maintain a boil during the entire process time. As long as a complete boil is maintained for the processing time the heat setting can be lowered a little. If the water stops boiling at any point the water needs to be brought back to a rolling boil and begin the timing of the process over from the beginning.
Step 7) If needed, add more boiling water to keep the water level above the jars. When the jars have been boiled for the recommended time, turn off the heat and remove the canner lid. Wait 5 minutes before removing the jar.
Step 8) Use a jar lifter to remove the jars from the canner. Place them on a towel, making sure to leave one inch spaces between the jars during cooling. Let the jars sit undisturbed to cool at room temperature for 12-24 hours.