Dating old kerr jars
Kerr, in 1915, created a flat metal disc lid to fit onto a Mason jar to use with other canning jars. Look for the Kerr name, which is embossed onto the surface. If the base is smooth at the jar's lip, it was made by a machine after 1915. A number is usually embossed on the jar's bottom, dubbed a "mold number." This will refer to the blower and his team. Look for small scars at the bottom and look to see if the design is more modern.
This means it would be post-1930, during days of more efficient machines.
This ancient trade started sometime around the 4th century and lasted well into the 19th century.
Following a successful shipwreck discovery, the company obtain a government permit to excavate the wreckage, and then carry out detailed marine archaeological procedures in recovering the artifacts, mapping the ship's remains and securing other data for future research.
Many of the earlier ECONOMY types are marked with the words “KERR GLASS MFG.
This was done in order to formalize and to expand on the founder’s extensive knowledge of Asia’s ceramic developments and maritime trade.(They also produced large quantities of other types of glass containers, especially in later years).Their most famous and important fruit jar in the early years was their “Kerr – Economy” jar, made in large quantities at their plants in Altoona, KS and Sand Springs, OK.San Francisco man Julius Landsberger patented metal lids fastened onto a composition gasket.Kerr used the patents to create a revelation in preserving food. Jars not made by machines were free blown; no mold was used.