If you are an avid beach glass collector, or a collector of glass bottles, jars, cups, etc, you may have noticed an odd symbol and/or numbers on your find and didn't know what they meant. Usually, the symbols are a logo for a company, and the numbers a code for where and when the particular glass item was produced.
With this hub, I am going to focus on the methods used by the Owens-Illinois (O-I) Company, and show you how to date your glass finds using the symbols and numbers indicative of the O-I company.I am by no means an expert on the numbers, nor am I an expert on how to date glass using the numbers, but I have done a lot of research on the subject, and I am relaying the information I have acquired along my internet travels.By the time 1940 came along, the company realized year codes were beginning to repeat, so in the 40's they implemented adding a period after the date code to indicate years 1940 -1949.By the mid-40's most plants switched to using a two number date code (such as 46 for a production year of 1946).The symbols, therefore, are quite faded.) Production of this particular mark ended somewhere in the mid 1950’s.
There is no exact year in which production of the symbol stopped, as various plants ended use of the mark at different years.
They started the switch to plastic in the 60's and 70's.
That narrows down the date from 1957 to 1977 if the 7 is indeed a year code.
The symbol, seen in the pictures below labeled Exhibit B and Exhibit C, contains an I inside an oval with an elongated diamond superimposed over it.
(Sorry I don't have better pictures, the glass is quite old and had been in the water for quite some time.
Coca-Cola and Pepsi-Cola didn't always adhere to the Owens-Illinois policies, and often had their dates on the heel, and not the bottom, of the glass.