There is a lot variety possible within each category of pontil marks.
Typical examples of the 3 major pontil types - glass-tipped or "open" pontil scar, iron or "improved" pontil scar, and sand (disk) pontil scar - are pictured to the right.
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).
At least a few American glass companies were hand-blowing bottles into the mid-20th century (Toulouse 1971).
The following Questions #5, #6, and #7 can help with dating, but also function to channel a user to specifics found elsewhere on this website.
In particular consult the Bottle Typing & Diagnostic Shapes complex of pages for more bottle type specific dating.
In particular, the information found within the Bottle Typing & Diagnostic Shapes complex of pages is of particular use.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.