Four quadrant dating

Certainly there were differences between individual glass companies in both of these large glass making regions, but the noted trend was supported by their exhaustive research of hundreds of bottles and the companies that used them. Certain classes of "specialty" bottles were made using glassmaking techniques from earlier times.

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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.

It is the most succinct period description of the use of a pontil rod the author has run across.

As discussed on the Glassmaking & Glassmakers page, various non-fusing, bottle base grasping tools (snap or snap-case tools) were already in use by glassmakers in the U. by the early 1850s (if not a bit before) to some degree and were dominant by the time of this patent was granted in November 1865; a patent for the refinement of such tools not for the concept itself: In the manufacture of glass bottles great difficulty has been experienced in holding the bottles in a proper manner for finishing the necks.The rod had to be long enough so that the heat transference from the extremely hot (2000 F.) bottle did not reach the hands of the pontil rod holder.A pontil rod held the bottle during the steps in the bottle blowing process where the blowpipe is removed (cracked-off) from the bottle and that break-off point is "finished", i.e. (Click empontilling and cracking off to see an illustration of these processes.) The process of applying the pontil rod to the base of a glass item (or the later use of a snap tool) and the detachment of the blowpipe was called "reversing" by glass makers (Trowbridge 1870).It will be recollected that during the process of uniting the punty to the bottle the bottle is in a plastic or flexible state in consequence of the heat it still retains after having been withdrawn from the mold, thus rendering it liable to get out of shape.Another objection to the old method is that when the bottle is completed the portion of the glass adhering or connecting the bottle to the punty is broken by a sudden jar by the operator, which leaves a rough place on the bottom of the bottle.For example, in the bare iron pontil section below is pictured an early 1850s mineral water bottle with an iron pontil that visually appears to be just a worn circular area in the middle of the base.

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