Four quadrant dating
These bottles would then appear to have been produced with a snap case tool when in fact they were made with a pontil rod.
This likely happened with any of the empontilling methods discussed below but in particular is thought most likely with the sand pontil, glass tipped pontil, and bare iron pontil since examples of all have been noted that were very obscure and difficult to see (empirical observations).
Thus, utilitarian bottles a pontil scar can date as early as the early 1850s (rarely earlier) and pontil scars can be found - though very infrequently - on utilitarian bottles made in the late 1860s and even early 1870s (Toulouse 1968; Newman 1970; Munsey 1970; Watson & Skrill 1971; Innes 1976; Jones 1986; Jones & Sullivan 1989; Mc Dougall 1990; Pastron & Hattori 1990; Van den Bossche 2001; empirical observations).
Supporting the above estimates is one study of medicinal bottles which determined that the peak of transition from pontil rods to snap case tools was during the period from about 1853 to 1856 with utilitarian bottles made during or prior to 1845-1850 having less than a 10% chance of There were also regional glass maker differences for this transition period also.
The base of a bottle which was held with a pontil rod will almost always retain some evidence of the pontil rod attachment. (It should be noted that bottles having no evidence of a pontil scar of any type are typically referred to as having a "smooth base;" click smooth base to see that discussion on the Bottle Glossary page.)The following description of this process is from an 1865 patent (U. Patent #51,058) for an "Improved Clamping-Punty" - a patent for one of many improved grasping devices which replaced the pontil rod and were a much quicker method of holding a bottle by its base for finishing.To view a picture of an early American flask that appears to have been fire polished click sunburst flask.This flask, classified as GVIII-2 by Mc Kearin & Wilson (1978), was produced in Keene, NH. Though likely fire polished, this bottle still has the pontil scar in evidence.3.(The image to the left is of a late 19th to early 20th century turn-mold barber bottle that has a distinct blowpipe pontil scar with some residual iron, i.e., like a "combination" pontil .) Many specialty bottles were imported from Europe, though that fact may be hard to ascertain. Some early 19th century bottles - particularly decorative bottles intended to be kept indefinitely - were often fire polished as the final step in the production process.However, many specialty bottles, most notably liquor decanters, had the pontil scars ground away leaving a shallow depression where the scar used to be (Munsey 1970). Pontil rods were (and may still be) used up until recent times at Mexican decorative glass factories and by small scale art glass producers in the U. Fire polishing was reported to have been developed by the English in 1834, though some American flasks from an earlier period appear to have been fire polished.