What do the numbers [on the bottom/sides of jars] mean
Collectors frequently refer to these numbers as “mold numbers.” However, in some cases, this term oversimplifies what the numbers represented. Originally when jars were blown by hand, the number represented a specific glass blower and his team. At the end of the day the blower and his team would get paid for the amount of jars they produced as determined by the number of jars made with a given number on them. I.E. glassblower #3 made 200 jars that day and he and his team therefore gets paid X number of dollars at X cents per jar produced. Later, when glass making went to machine the numbers represented the mold or machine the jar was made from (usually 4-8 molds per machine or one to several machines per factory.) That way the plant manager could check quality control, production, etc. Today you can frequently find numbers on new jars that indicate date of manufacture, plant location, job number, etc.
