A Mason jar, also known as a canning jar, preserves jar or fruit jar, is a glass jar used in home canning to preserve food. It was named after American tinsmith John Landis Mason, who patented it in 1858. The jar's mouth has a screw thread on its outer perimeter to accept a metal ring or "band". The band, when screwed down, presses a separate stamped steel disc-shaped lid against the jar's rim.
After Mason's patent expired, numerous other companies began manufacturing similar jars. Over the years, the Brand Mason became the genericized trademark for that style of glass home canning jar, and the word "Mason" can be seen on many Ball Corporation and Kerr brand jars. The style of jar is occasionally referred to by common brand names such as Ball jar (in the eastern US) or Kerr jar (in the western US) even if the individual jar is not that brand. Canning — On the Ball? Do you Kerr? It's all straight from the Jarden, October 5, 2020 Kerr Mason Jars
In early 20th-century United States, Mason jars became useful to those who lived in areas with short growing seasons. The jars became an essential part of farming culture, while being used at fairs to display jams and pickles for judging and awards. This was a reflection of the labour that went into making the jams. The jams, pickles, and sauces would be given and exchanged as gifts during the holidays as a canned preserved good was of much value. The peak use of Mason jars came during World War II, when the U.S. government rationed food, encouraging the public to grow their own. As migration to cities occurred, along with the rise of refrigerators, the more efficient transport of goods made fruit and vegetables available year-round, reducing the need for food preservation. Contemporary industrial preservation transitioned to the use of plastics like bakelite and nylon and billions of containers were produced instead.
On August 15, 2017, the registrar at National Day Calendar proclaimed National Mason Jar Day to be observed annually as a national holiday on November 30, beginning in 2017.
The initial form of closure for the glass canning jar was a zinc screw cap, the precursor to today's screw-on lids. It usually had a milk glass liner, but some of the earliest lids may have had transparent glass liners. The cap screwed down onto a rubber ring on the shoulder of the jar, not the lip. Food Bottles, The Society for Historical Archaeology Between 1860 and 1900, many other patents were issued for Mason jar improvements and closures. In 1903 Alexander Kerr introduced lids with a permanent rubber seal. His improved design in 1915 used the modern design. Jars are closed with two-piece metal lids that seal on the rim. The jar lid has a rubber or rubber-like sealing surface and is held in place by a separate metal band.
Mason sold the patents for the Mason jar to the Sheet Metal Screw Company of Lewis R. Boyd in 1859. Boyd had patented a white milk-glass insert for the zinc screw lids to theoretically lessen the chances that food would be tainted by contact with the metal lid. In 1871, Mason partnered with Boyd in the Consolidated Fruit Jar Company which licensed Mason jar patents to numerous glass makers. A PRIMER ON FRUIT JARS , Dave Hinson, Bottles and Extras, The Federation of Historical Bottle Collectors, 1996 Letters of patent issued to Mason on May 10, 1870, for improvements to his fruit-canning jar was determined to be invalid as a result of a patent infringement case brought before the Southern District of New York on June 11, 1874. The court acknowledged that Mason invented the jar in 1859, but he did not apply for a patent for an improved version of the fruit jar until 1868. In the meantime, several others had patented designs and Mason had known these jars were being produced and sold. The court ruled that Mason's delay in protecting his patent indicated he had abandoned his invention in the intervening years between 1859 and 1868 and had forfeited his patent. The court's decision allowed other manufacturers to patent, produce, and sell glass jars for canning."The Consolidated Fruit Jar Company vs. James T. Wright. In Equity" in
The jars are made with either a wide mouth () or regular mouth () opening. They come in a variety of sizes, from 4 ounces to a gallon. The half-gallon size and larger are not recommended for canning purposes. The most typical sizes used in canning are quart, pint, and half-pint. The jars typically have their brand name embossed on the side, though jars may also have a decorative design such as a quilting pattern or may be completely blank and smooth. Jars may be washed and reused so long as they have no chips or cracks.
In the illustration, the left half are wide mouth and the right half are regular mouth. From left to right: wide mouth half-pint, pint, pint, quart, then regular mouth quart, pint, half-pint, quarter-pint. The lids and bands are also shown. The two rightmost jars are quilted.
The lids are made of metal with a ring of sealing compound which acts as a gasket against the jar's rim. New sealing compound is only good for about five years from date of manufacture, so older unused lids should be discarded. Lids may not be used more than once. New lids are slightly domed (convex). During processing, air is vented from the jar and the food shrinks. While cooling, a vacuum is created inside the jar, sucking the dome downward (concave) – an indication that a seal is good. Cooling Jars and Testing Jar Seals Processed jars should be stored in a manner where the lids are not disturbed and the seals remain intact. Storing Home Canned Foods: Testing Jar Seals
The metal screw bands are used to properly align the lids onto the jar, and to hold the lid in place during processing. They should be removed after processing and may be reused many times as long as they are kept rust-free and undented.
Most antique jars that are not colorless are aqua or "Ball blue," a blue-green shade that was named for the Ball Corporation, a prevalent jar manufacturer. Most mouth-blown Mason jars embossed with some type of 1858 patent date were produced in aqua glass. The Ball brand of Mason jars were manufactured in several colors, but the most common color was the distinctive "Ball blue," which the Ball Corporation used in its jars from about 1910 to 1930. Mason jars with this particular color of glass may be attributed to Ball, since "virtually no other bottle or jar was made in that color."
Older styles of home canning jars are "not recommended" by the U.S.-based National Center for Home Food Preservation, the United States Department of Agriculture, and University Extension Services. These include: those using a zinc cap and a rubber jar ring, and those using a glass lid, wire bail, and rubber sealing ring. These provide "no definitive way to determine if a vacuum seal is formed".Patti Griffith, University of Wyoming Cooperative Extension Service, in her reference to the use of older versions of Mason jar closures, explains, "Jars requiring a zinc cap and jar rubber or jars requiring a glass lid, wire bail, and jar rubber have not been recommended since 1989 because there is no definitive way to determine if a vacuum seal is formed."
The jars have been used for a variety of household functional and decorative purposes. Mason jars have been turned into items such as oil lanterns, soap dispensers, speakers and vases.
Design variations
Ball Corporation brands
Contemporary jar design
Collecting vintage jars
Other uses
See also
General references
External links
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