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
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