Dating base 1
The shift to the fully automated bottle machine from mouth-blown and some semi-automatic methods in the early 20th century is the classic example (Toulouse 1967, 1969a). The same bottle could have been recycled and reused many times for many years before finally being discarded - entire or broken (Busch 1987).
This was almost universal with many beverage bottle types (e.g., soda, beer, milk) but was variably common with just about any type bottle - especially prior to 1920.
This bottle dating "key" is a relatively simple "first cut" on the dating of a bottle.
To misquote an old saying as rephrased by the BLM supervisor that facilitated the initiation of this website project: "The universe (of bottles) isn't just more complicated than you think, it's more complicated than you CAN think." True to a large degree, though much information can be teased out of most bottles with a systematic approach to the matter. This Bottle Dating page (and website in general) is designed to address what the website author refers to as "utilitarian" bottles & jars (click for more information).
This page and associated sub-pages allows a user to run an American produced utilitarian bottle or a significantly sized bottle fragment through a series of questions based primarily on diagnostic physical, manufacturing related characteristics or features to determine the approximate manufacturing age range of the item.
As Berge (1980) noted in referring to bottles, the "..of manufacture of glass containers provides observable attributes which seem to be very useful in a classification of these artifacts." Thus, this page.
Utilitarian items makes up the bulk of the bottles produced during the 19th century and first half of the 20th century. Bottles intended to be used once to dispense the contained product without much hope of return, though as noted in #4 above, many types of bottles were commonly reused during the 19th and early 20th centuries; or 2.
Heavy duty bottles intended to be recycled and reused by the producer or distributor of the contained product (primarily soda, beer & milk bottles); or 3.
Pontiled base fragments could also be from later produced "specialty" bottles which are described below.5.