A Brief History of Mason Jars
Canning or fruit jars became known as mason jars, named after the inventor, John L. Mason. As most everyone knows, the mason jar is a reusable glass container with a thread in the top. It is used with a zinc lid and rubber ring to seal it. These jars are embossed with "Mason's Patent Nov. 30th. 1858." Manufacturers of mason jars continued using this embossing until approximately 1920.
Other types of closures for mason jars followed, including zinc screw lids with a white milk-glass insert, glass lids with a thumb screw clamp, glass screw on lids, and glass lids with a wire bale. In the 1920's, came the Atlas E-Z Seal and Atlas Strong Shoulder jars. Then Alexander H. Kerr used patents held by Julius Landsberger to product the Economy jar with a metal lid with a permanently fastened composition gasket. The Economy jars were inexpensive, and easy to use and fill. In 1915, Kerr invented a lid composed of a metal disk with the same gasket attached. The lid sealed the jar and a threaded metal ring held it in place. This new Kerr lid allowed for the re-use of canning jars.
In the late 1880's, the Ball brothers built an empire to mass produce and distribute canning jars throughout the country. During World War II, an effort was made to conserve the use of steel and tin for the war effort. Glass lids temporatily replaced the tin and zinc lids on mason jars. After the end of the war, home canning began to decline.
The value of a canning jar depends on the embossing, color, shape, mold marks, size and type of closure. Very common mason jars are worth under $10, while some rarer versions can be worth $100 or more to collectors. Square jars tend to be worth more than round jars, since fewer square jars were made. In addtion, jars with the number 13 seem to be sought after by some collectors. The number identified the glass blower and his/her team.
Dating Your Mason Jars
You should look at the bottom of your canning jars to see if there is a pontil mark, left by a glass blower. The oldest bottles were made by glass blowers and have no seams. If so, the jar is probably pre-1855. Older jars will also have a rough lip compared with newer jars. Seams are indicative of a jar that is machine made. Machine made jars had mold seams from the bottom to the top of the jar. These jars are circa 1915 or later.
Do you collect mason jars? Please comment to share your experiences!