Clear glass beer botttles bottom dating
Sometime around 1880 it became common practice to tool the lips with a lipping tool, an object which fit one piece into the opening of the neck while two other pieces clamped on the outside of the applied band of glass.
Larger bottles and especially soda bottles made between 18 have pontil marks.Bottles produced during the last twenty years of the last century will show evidence of this twisting motion which left faint concentric rings around the mouth and upper part of the neck.This motion also erased the mold seam in the process.Molds were designed with a particular base called a "key mold" this mold left a distinctive mark on the base of bottles made between 1850-1870.Key mold bottles can be found both pontiled and smooth based As mold making technology progressed the seam across the base of the bottle disappeared.The practice of using private molds became popular around of the middle of the nineteenth century.
These mold were ordered from the glass factories by medicine manufacturers, soda and mineral water bottles and manufacturers of other household goods.
Most bottles dating before 1855 will have an open pontil.
There are several types of open or pontil marks but the key is the presence of a rough area on the base.
Looking at the base of a bottle is also helpful in determining the age.
Most bottles made before 1858 will have a "pontil" mark.
The letters ABM (automatic bottle machine) are used to refer to these bottles.