Canning Jar Information

The typical jars used for home canning use are named "Mason" after John L. Mason, the inventor of the first common canning jar.

Mason jars can come in half-pint, pint, quart, and half-gallon sizes, but most canning recipes use measurements for the pint and quart sizes. The half-pint jars are usually used for jellies or small spreads. Half-gallon sizes are more unusual and more difficult to manage.

Some old canning jars have a blue color. This blue color makes them quite valuable. Using a colored jar can help preserve the food better by keeping less light from entering.

Mason jars have either small or wide mouth openings. The wide mouth jars are important for easy access if the food is frozen or more bulky.

The most common jars used today are the metal screw-top variety, although you may also find the bail-wire-clamp in use. It is said that the screw-top jars provide the most reliable seal.

The metal lids have two pieces, a flat lid that covers the opening, and a screw-on band that holds the lid in place. The flat lid has a sealing compound around the edge and is only able to be used once for canning. The metal screw-on band can be reused multiple times, as long as it is kept free from rust and is not bent.

Before canning with a jar, make sure that the rim is free from nicks or cracks. The rim surface of the jar must be in perfect shape in order to complete a solid seal.

Different foods are canned differently. The canning method to use depends upon the acid content of the food. Foods with a higher acid content are less likely to spoil and need less heat and time in canning. Lower acid foods spoil much easier and need high heat and longer cooking times.

The different methods of canning have different names. Pressure canning is canning with the use of a pressure cooker. A pressure cooker is needed to reach high temperatures for canning low acid foods.