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 do you tell how old your mason jars are?

Some helpful notes to keep in mind:Not every jar has their manufacture date on the glass, but most have the patent date. There will be a large number on the bottom of your jar. These charts tell you the approximate decade in which your Ball jar was made.More items •16 Aug 2021

How old are Kerr self sealing Mason jars?

These jars were made from 1904 until World War II, when they were discontinued in favor of the Kerr Glass Top. The line was reinstated about 1946, and production continued until at least the 1980s. All of these jars had the Mason beaded neck style, although the actual seal was at the lip or rim of the jar.