Dating bottles by their tops and bases
In these cases, the general style, shape, glass color and other characteristics may help narrow down the possible age range of a particular specimen.
A large percentage of bottles are marked with only a number, or numbers, on the base (or the heel), and the truth is that, in embossed in the glass.
Probably in the majority of cases, single digit numbers are mold numbers, merely serving to identify a particular mold, (or section/mold cavity in an automatic bottle manufacturing machine) that was used to form the bottle or other glass item.
If a number of identical bottle molds are being used simultaneously, each mold would be assigned a number.
-Embossed on the base is MISSION DRY CORP., some numbers & letters, and a symbol. It is apparent that the answer to Question #1 is "YES" since this bottle has raised embossing in the form of the "swirls" on the shoulder.Many Owens-Illinois Glass Company soda bottles, for a period of time, used “G-numbers” on the bottom (numerals before or after a G), which were codes for a specific bottle shape (design), irrespective of the soda brand name or glass color.