By Gail Damerow

Canning jars come in two main categories, depending on the diameter of the opening. A narrow mouth jar, also known as a regular or standard jar, has an opening 2-3/8 inches in diameter. The opening of a wide mouth jar is 3 inches in diameter.

Since lids for sealing canning jars come only in those two sizes, the first consideration in selecting jars for canning is to make sure their mouths are one of these two dimensions. The second consideration is to decide what foods you will be canning, because the required method of processing a particular food determines to some extent the kind of jars that are suitable.

Repurposed Jars
When I first started canning on my own, a lot of foods sold at the grocery store came in glass jars that fit one or the other size canning lid. I repurposed a lot of one-quart mayonnaise jars, in which I canned apple juice from our orchard. A friend, who ate a lot of oysters that came in jars, kept me supplied in a size jar I found perfect for putting up salsa.

Other foods also came, and sometimes still come, in jars that fit wide or standard lids. Such jars may be cheap or free to acquire, but they are not ideal for canning. For one thing, the top edge tends to be thinner than the edge of a regular Mason jar, and may be rounded rather than flat, therefore offers less surface area for a lid to seal tightly against. Further, repurposed jars are not as well tempered as Mason jars, and therefore tend to break more easily, especially if they are used for canning vegetables or meats that require processing under pressure. Who wants to grow, pick, clean, and cut a canner load of green beans, only to end up with a pot full of beans floating in broken glass?

So, as time went on and I gained confidence in my canning abilities, I acquired Mason jars so I could try my hand at pressure canning. As my collection of jars grew, I weeded out the repurposed jars in favor of the more versatile Mason jars, which may be used for any processing method.

Mason Jars
The Mason jar as we know it today was invented in 1858 by a Philadelphia man named John Landis Mason. Even after early competitors like Ball, and more recent ones like Fillmore, entered the market, the jars continued to be called Mason jars, as they are to  this day.

Mason jars come in several sizes. The variety may at first seem confusing, but selection becomes easy if you think about what you intend to put in them and how much of that food you would normally use within a reasonable amount of time after opening a jar.

The smallest jars are four-ounce (one-half cup) so-called jelly jars. These jars are promoted as being suitable for jams, jellies, condiments, and flavored vinegars. In our house we find them ideal for canning liverwurst, since one jar holds just enough for four sandwiches.

Jelly jars come in two other sizes—eight-ounce (one cup) and 12-ounce (one and a half cups). All jelly jars are straight sided and take a standard-size lid. Some brands have a quilted pattern or other decorative embossing, making them attractive for gift-giving.

Plain eight-ounce jars are also sold as half-pint, which are the same as eight-ounce jelly jars except they have no decorative pattern. I have a large collection of both styles and use them interchangeably. Plain half-pint jars also come in a squat wide-mouth version that I don’t find particularly handy for routine canning.

At our house we use the regular eight-ounce size for specialty pickles, such as pickled beets or pickled green beans and relishes. For jams and jellies we find the 12-ounce jars to be the handiest size.

Pint-size Mason jars come in both standard and wide mouth. The wide-mouth jars are easier to fill and empty, but the lids are more expensive. At our house, nearly all our fruits, vegetables, soups, and stews go into one-pint jars, because that’s how much my husband and I can finish in a single meal. We also put up salsa and spaghetti sauce in pint jars.

Pint-and-a-half (three cups) Mason jars come in wide mouth only. We use ours primarily for putting up pickles cut into spears, as they nicely fit vertically into these jars.

One-quart (32-ounce) Mason jars come as both wide mouth and standard. We use our wide mouth quarts primarily for canning tomatoes and our narrow mouth quarts for apple juice. Larger families than our two-person household generally find one-quart jars more suitable than one-pint jars for canning fruits, vegetables, soups, and stews.

The largest common Mason jars are half-gallon (64 ounces) and are sold for canning acidic juices. Only the wide mouth version is currently available, but standard half-gallon jars might still be found at yard sales and flea markets. I have a few of both, but I don’t use them for canning. I use the narrow mouth half-gallons for chilling iced tea, because they’re easier to pour from. I use the wide mouth half-gallons to store our goat milk, because the rising cream is easier to skim than from a narrow mouth jar. I use the wide mouth also for storing dried beans and pet food.

Care Of Mason Jars
Before each canning session, check your Mason jars for cracks in the glass or chips around the rim. Careless handling of jars is the most common cause of cracks and rim chips, which prevent a proper seal. Cracks may also result from putting jars filled with cool food into boiling water in a canner for processing, which can cause a jar’s bottom to crack. Sometimes the entire bottom drops off the jar, resulting in the loss of both the jar the food in it.

After inspecting your jars, wash and rinse them by hand, or run them through a dishwasher. I like to use the dishwasher because it keeps the jars hot until I’m ready to fill them.

With proper care, Mason jars may be used over and over again, and will last nearly forever. Barring accidents, the jars rarely break during processing, and when properly sealed, the vacuum holds until the jar is opened.

You don’t have to spend much time canning before you learn to value your canning jars and start keeping an eye out for season-end bargains and garage sale finds. You also come to appreciate your non-canning friends who are savvy enough to return empty jars after you’ve gifted them with some of your home canned goodies.

Sterilizing Jars
Contrary to popular belief, washing jars in a dishwasher does not sterilize them. In fact, routinely sterilizing jars is entirely unnecessary, as long as the food they contain is processed for at least 10 minutes. The main reasons for so-called sterilizing jars is: 1) a cool jar filled with hot food runs the risk of breaking; and 2) a cool jar may reduce the temperature of heated food before it reaches the canner.

For these reasons, I leave jars warming in the dishwasher until I’m ready to fill them. If I get delayed long enough for the jars to cool, I fill them with hot water to keep them warm.

Some jams, jellies, and pickles are processed for less than 10 minutes. In such cases, place clean, empty jars upright on the canner’s rack, and fill the canner with hot water to cover the jars by at least an inch. Bring the water to a boil, and boil for 10 minutes (adding 1 minute for each 1,000 feet you are above an elevation of 1,000 feet). Remove, drain, and fill jars one at a time, saving the boiling water in the canner for processing the batch after all the jars are filled.

Canning books typically suggest using a jar lifter to remove empty jars from boiling water, but in my experience a jar invariably slips off the jar lifter when tilted to drain out the water. For this purpose, I instead prefer to use sturdy tongs. With one prong inside the jar, and one outside, the tongs retain a tight grip when the jar is upended for draining. Be sure to wear an oven mitt so the rising steam won’t scald your hand. After each jar is filled, a jar lifter is ideal for returning it to the canner.

CANNING CODE:

JAR LIFTER: A device for safely putting jars into or removing them from  a canner.

JELLY JAR: A straight-sided decorative canning jar holding 4, 8 or 12 ounces.

MASON JAR: A well-tempered jar designed specifically for home canning; also called a canning jar, fruit jar, Ball jar, or Kerr jar.

NARROW MOUTH: A canning jar with a 2-3/8 inch diameter mouth; also called regular or standard jar.

WIDE MOUTH: A canning jar with a 3-inch diameter mouth.