Dating aqua ball jars
Early SURE SEAL jars were regular size mouthed jars like the Ball IDEAL jars.Later SURE SEAL jars are widemouth type, along with the SANITARY SURE SEAL series.The "rounded-square" shape was adopted in 1942 as a way to save glass.(the war board required all glass manufacturers to adopt this shape because they determined that it was the most efficient shape to contain a volume).All have seams, which tells me they were maybe blown into or cast in a mold.The lip of the one with the C bump is very rough and the lower seams don't line up with the seams on the jar's top.In 1915, the Ball IDEAL was introduced into the line.
I see a lot of jars listed on ebay incorrectly with pontil marks. There are only a FEW very early fruit jars which have pontil marks, and these have an applied lip of some kind.English measurements (ounces and cups) on the side started about 1956.Ball was the first fruit jar manufacturer to do this..These are the first of the famous Ball PERFECT MASON jars, excluding the BOYD/BALL reworked moulds which have all the lettering in block letters.The embossing was centered starting in about 1915..