For example, an Atlas Mason jar may be considered too old if the mold seams arent visible anymore. Its also good to know that any Atlas Mason jar that was made before 1915 didnt have any visible seams because they were hand finished.

How can you tell if Mason jars are old?

AgePontil marks or indented rings in the bottom of the jar mean it was hand finished by a glass blower. Seams also help determine the age of your jar: Seams that go all the way up the jar indicate it was machine made, probably between 1895 and 1915.Color can also help date your jar.