Other diagnostic tools must be used to date these items.
Shape is more indicative of function - i.e., what the bottle was used for or contained - but even that has a myriad of exceptions.
This bottle dating "key" is a relatively simple "first cut" on the dating of a bottle.
While running a bottle through the key questions, the user is frequently directed to move to other website pages to explain diagnostic features and concepts as well as to add depth and/or precision to the initial dating estimate.
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.Please be aware that in order to gain the maximum information about any particular bottle (e.g., dating, typing) the user must usually must review a number of pages within this website.Unfortunately, the complexities of precisely dating bottles is beyond the scope of any simple key.Utilitarian items include canning/fruit jars and figured flasks since they were intended to be reused by the purchaser and have been observed to follow well the dating guidelines, though there are some manufacturing timeframe differences with canning jars.(Click canning jar to view the typology page section devoted to that category.) The beer bottle pictured to the above left is a classic example of a utilitarian bottle from the late 19th century that was typically reused.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.We can always have some indication of a starting date for a technique if we can find who first put the idea into practice.But any technique, once developed, can be used right up to the present - as many collectors know who have been so unfortunate as to rely too heavily on a popular termination date as sure evidence of true antiquity..." (Toulouse 1969b).In short, there was (and is) nothing to stop a glassmaker from using an obsolete method in the production of a bottle.3.Some technological changes were expensive and not adopted by glass makers until it became an "adapt or perish" issue and many glass factories just perished.