Film clip is compliments of the Owens-Illinois Glass Company.
(Many thanks to Phil Perry, engineer with that company.) Mouth-blown utilitarian bottles have several important diagnostic characteristics which can be helpful for dating.
Probably at least 95% of pontil scarred utilitarian bottles date to or before the Civil War era (1860-1865).
The gaffer makes the gather from the glass pot/tank in the background, rolls and pre-forms the parison on the marver (table to the left), then quickly drops the parison into the mold which the mold boy efficiently snaps shut.
The gaffer quickly inflates the bottle and efficiently bursts-off the blowpipe while pulling the blowpipe away from the mold.
In particular, the information found within the Bottle Typing & Diagnostic Shapes complex of pages is of particular use.
: If you are keying a bottle with a ground lip or finish, only questions #6 & #7 will help refine your dating quest since ground lip bottles and jars are rarely pontil marked (Question #4) and this finishing method is not covered under Question #5 (it falls out as "C" - Other Finishes - under Question #5).
Directly in front of the standing boy is most likely the marver - a flat table used for parison manipulation.
The caption to the photo is: "Blower and Mold Boy, Seneca Glass Works, Morgantown, W. Location: Morgantown, West Virginia."The large majority of mouth-blown bottles (probably at least 95%) date to or prior to the World War I era, i.e., ≤1915-1920, with at least 75% likely dating prior to 1900 (empirical estimate).
If you are seeking information on what type bottle you have, go to the Bottle Typing & Diagnostic Shapes page which also will lead users to additional dating information.
have any evidence of a pontil mark though the base may have a mold line(s) and/or embossing, or be totally smooth and unmarked.
Those “Best by,” “Use by” and “Sell before” dates stamped on the food we buy can be a source of continued confusion for consumers.
Earlier this year, Congressional efforts to clarify reliable expiration dates only highlighted the problem.
(This is particularly interesting to see and shows that shearing or cracking-off wasn't always used or necessary.) The mold boy then removes the bottle from the mold with tongs while the gaffer knocks off the residual glass from the end of the blowpipe and then moves back to the glass pot/tank to make another gather.