Pontil scars on dating glass magellan updating

Known as empontilling, this transfer allows the glassblower to form and finish the bottle’s mouth or bore.

One of the easier to identify and most consistently accurate indicators that a bottle was manufactured during or prior to the American Civil War (i.e., the 1860s or before) is the pontil scar present on the base.

In actuality, the residual red, reddish black, gray, or black deposits are iron, typically oxidized iron – ferric (red) and ferrous (gray, black) oxides (Toulouse 1968; Mc Kearin & Wilson 1978).

The iron pontil scar is the result of using a bare iron pontil rod with an appropriate shaped tip or head which was heated red hot and directly applied and fused to the base of the bottle to be held.

This is usually manifested primarily by an assortment of glass fragments protruding above the base of the bottle.

See image #1 which is a mid-19th century sauce bottle.

The mark is formed when a bottle is transferred from the blowpipe to the pontil rod, which, unlike the blowpipe, is solid.A larger connecting surface at the end of the pontil rod was necessary with this method in order to ensure an adequate adherence to the bottle base and was of particular use with the ever increasing numbers of molded bottles during the first half of the 19th century.The sand pontil apparently conformed better than other pontil types to molded base shapes without distorting it (Jones 1971; Mc Dougall 1990).This attachment process was called “empontilling.” 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.This is circumstantial proof that one blowpipe was usually used for both blowing and empontilling.


Leave a Reply