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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).
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.
Additional reference materials outside of this website must often be consulted to narrow down the date of any item as far as is possible and to really get a "feel" for the history of the bottle in question.
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.
An example of this is the finding of a few pontil scarred utilitarian bottles among otherwise late 19th or early 20th century refuse.
It is unlikely that this bottle was made during the same era, but instead was reused for a lengthy period or otherwise retained until broken or discarded.
Other diagnostic tools must be used to date these items.