Check the jar from top to bottom. The Kerr name will be embossed on the glass. There are some general guidelines to approximate the date of a vintage Kerr jar between 1915 and 1930. The finish on a fruit jar can tell you roughly about the date it was made.
How old is this Kerr jar?
Kerr self-sealing jars and the Kerr Economy were created in 1903. Alexander H. Kerr also founded the Hermetic Fruit Jar Company in the same year. San Francisco man Julius Landsberger patented metal lids fastened onto a composition gasket.
What does the numbers on the bottom of Mason jars mean?
Many Ball mason jars have a number printed on the bottom of the jar, but this is a mold number that does not indicate the year of production. Rather, the mold number tells you where the jar was positioned on the glass-making machine that was used to produce it.