Mason & Kilner Jars

French chef Nicolas Appert invented the method of preserving food by enclosing it in sealed containers. Among the earliest glass jars used for home canning were wax sealers, named in reference to the sealing wax that was poured into a channel around the lip to secure a tin lid. This process, which was complicated and error-prone, became popular in the late 1830s or early 1840s and was still used to seal fruit jars until about 1890. The wax sealing process was largely the only one available until other sealing methods were developed. Competitors including jars with stoppers, spring wires, wire bails, cantilevered wires, and thumbscrews all proved less successful.

In 1858, a Vineland, New Jersey tinsmith named John Landis Mason (1832–1902) invented and patented a screw threaded glass jar or bottle that became known as the Mason jar (U.S. Patent No. 22,186.) From 1857, when it was first patented, to the present, Mason jars have had hundreds of variations in shape and cap design. After it was discovered that Mason's patent had expired, many other manufacturers produced glass jars for home canning using the Mason-style jar. "Patent Nov 30th 1858," signifying the date of Mason's patent, was embossed on thousands of jars, which were made in many shapes, sizes, and colors well into the 1900s. Since they were made in such quantity and used for such long periods, many of them have survived to the present day.

The initial form of closure for the glass canning jar was a zinc screw-on 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. Between 1860 and 1900, many other patents were issued for Mason jar improvements and closures. The more esoteric closures were quickly abandoned, and thus can fetch high prices in today's antique market. 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.

A Mason jar — named after John Landis Mason, who patented it in 1858 — is a molded glass jar used in home canning to preserve food. 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. An integral rubber ring on the underside of the lid creates a hermetic seal. The bands and lids usually come with new jars, but they are also sold separately. While the bands are reusable, the lids are intended for single-use when canning. Glass jars and metal lids are still commonly used in home canning while they have been largely supplanted by other methods for commercial canning (such as tin cans and plastic containers).

In home canning, food is packed into the Mason jar, leaving some empty "head space" between the level of food and the top of the jar. The lid is placed on top of the jar with the integral rubber seal resting on the rim. A band is screwed loosely over the lid, allowing air and steam to escape. The jar is heat sterilized in boiling water or steam and the lid is secured. The jar is then allowed to cool to room temperature.

The cooling of the contents creates a vacuum in the head space, pulling the lid into tight contact with the jar rim to create a hermetic seal. Once cooled, the band is removed to prevent residual water between the jar threads and the lid from rusting the band. If the jar seal is properly formed, internal vacuum will keep the lid tightly on the jar. Most metal lids used today are slightly domed to serve as a seal status indicator. The vacuum in a properly sealed Mason jar pulls the lid down to create a concave-shaped dome. An improper or failed seal or microbial growth will cause the dome to pop upward.

Kilner jar is a rubber-sealed, screw-topped jar used for preserving (bottling) food. It was first produced by John Kilner & Co., Yorkshire, England.

The Kilner Jar was originally made by a firm of glass bottlemakers from Yorkshire called Kilner. The original Kilner bottlemakers operated from 1842, when the company was first founded, until 1937, when the company went into bankruptcy. After being taken to court in 1871 over the coal smoke coming from their Thornhill Lees chimneys, the judge ordered that "no man has the right to interfere with the supply of pure air". The company was forced to close down to convert to gas furnaces and struggled along for 66 years despite 3,000 people losing their jobs. In 1937, there was a bankruptcy sale, in which the patent rights to the Kilner Jar were sold to the United Glass Bottle Manufacturers Limited (UGB), along with the rights to the Mason jar that had also been made by Kilner.

• Mason jar .
• Weck jar .
• Fowler's Vacola jar .
• Food preservation .
• Home canning .
• Screw cap .
• Sterilisation .