There a quite a few types of pontil marks or scars but the two most common are the open pontil (O. Bottles that exhibit either one of these marks will generally date between 18.The age of bottles dating after 1860 can be narrowed down by taking a close look at the lip of the bottle.The disk-like mark is sometimes confused with a pontil.the pontil is actually broken glass where the metal rod used to hold the bottle while the lip was form was broken off leaving a sharp scar.The base of the second bottle whose lip was shown above right is displayed here.The the lower left corner you can see evidence of the diagonal mold seam which at one time bisected the base.
The pressure from the automatic machine was strong and the molds fit tight leaving only a very thin line.
The food and household product industries on the other hand widely adopted the screw cap quickly.
One unique closure to the late 1930s was a three point screw top.
the bottle on the right appears to have a tapered collar a form which was very popular for more than 60 prior to the making of this bottle.
This is the base of the bottle whose lip is shown above left.