Here are two rules regarding equipment:
You'll need a pressure canner if you can vegetables (except for tomatoes, sauerkraut, and pickles), plus a kettle with a cover if you're canning fruits using the boiling water bath method.
Pressure canners are manufactured in various sizes: match your canner with your canning ambitions; and if you'll be doing a lot of canning, buy a big canner and save both time and heating costs with it. When using a pressure canner, follow the manufacturer's instructions. All canners require a rack on the bottom, so boiling water or steam can circulate under the jars.
The dial-type pressure canner has a gauge that shows the pressure, a petcock that allows steam to escape under a controlled pressure, and a safety valve that will pop and thus relieve pressure if the petcock becomes stuck. The gauge must be checked for accuracy each year.
The weighted-gauge pressure canner has a one-piece, metal weight-type pressure control. When the called-for pressure is reached, you will hear the control jiggle, releasing steam and preventing the pressure from rising higher.
A kettle with a cover is used for boiling water bath canning of high-acid foods. Most people use a conventional black enamel canner. It is resistant to acids and salt solutions, and so can double for cooking pickles or brining vegetables. The kettle must be deep enough so that jars sitting on a rack will be covered with at least an inch of water. There must be at least another inch in the kettle for the space required for a rolling boil.
Jars are sold in sizes from a half-pint to a half-gallon, and with a variety of lids. Most popular are the pint and quart sizes with the two-piece vacuum-seal lid held in place during processing by a metal band. With these lids, it's easy to tell when the seal is perfect. The lid makes a definite snapping click when it seals while cooling. The lid curves downward when sealed and remains so. When tapped with a spoon, the sealed lid rings clear.
You probably have many of the items you'll need. These include knives, long-handled spoons, saucepans, measuring cups, a colander, and scrapers. These are additional helpful aids:
The jar lifter is used for removing jars from the canner. Use one and you won't burn your hands.
The jar funnel with its wide mouth makes it easy to fill jars without getting the food on the rim of the jars.
A bubble freer is handy, cheap, and makes it easy to get bubbles out of the food before processing.
For a timer, look for a photographer's timer. It's accurate, and will tell you with a loud ring when time's up.
Here are three of the most common canning jars found today.
If you're buying jars, we recommend pint or quart jars with the two-piece vacuum lid. The underside of the lid has a strip of rubberlike sealing compound on the edge, where it comes in contact with the rim of the jar. A metal screw band holds the lid in place during processing, and is removed when the jar has cooled and the vacuum inside the jar holds the lid. These lids are discarded after one use; the bands are saved.
The older style jars that have caps with porcelain liners are sealed by placing a wet rubber ring over the neck of each jar. The cap is screwed on firmly, then backed off a quarter-inch to allow air to escape during processing. After processing, but while the jar is still hot, tighten the cap to complete the seal. Careful—it will be hot. Use potholders or oven mitts. When the jars are cool, test the seal by tipping them. Any leakage indicates the jar is not sealed.
The jars with wire bails and glass lids are still in use, although they haven't been manufactured for many years. A wet rubber ring is fitted over the neck so that it rests on the glass ledge of the jar. The glass lid is placed so that it rests on the ring. The long wire bail is set in place in the groove on the top of the lid, and the second bail is left in the up position. After processing, and while the jar is still hot, you should push the second bail down against the side of the jar. When the jars are cool, test the seal by tilting each jar.
When using any of these jars, do not attempt to open them to replace any liquid lost during processing.