Sometime late in the third quarter of the 19th century, glassblowers developed new methods to speed up and increase production. Semi-automated methods, and later fully automated methods left labor intensive hand production behind. One sign of a handblown glass object, whether a bottle, a pitcher, vase or bowl, is a distinctive sometimes sharp mark on the base of the object. This mark is called a pontil mark or pontil scar.
It is important to know that modern handblown glass often bears such marks so it is not a definite indicator of age. It can mean, however, a greater value for the object - for example, when comparing two otherwise identical bottles, the one with the pontil mark is almost always more valueable.
Why the Pontil?
A glassblower's assistant attaches a pontil rod to the object during manufacture to hold it in order to form a lip, attach a handle or complete other details.
Evaluating your Glass Object
If you are not sure exactly what you have and want to learn more about it, make the effort to take clear photographs of your bottle or glassware. Include photos of the base and other details. Look for any markings on the glass. Put together a description that includes the height, condition and history of ownership. Then you can start sharing this info with collectors online or request an appraisal.
You might also consider browsing auction results on sites like ebay.com. Ebay is not the only place that you should be looking; there are a number of auctioneers who specialize in antique bottles and antique glass such as Jeffrey Evans and Glassworks Auctions.
Types of Pontil Marks
Here are a few examples including an iron pontil, open pontil, ground pontil and pontil mark on a contemporary pitcher.
A classic well-defined ring pontil or open pontil mark. The pontil rod was sheared off at this point after the glassblowers finished forming the lip of the bottle.
This 19th century bowl has a somewhat faint ring pontil. The glassblowers attached the pontil in order to roll the edge of the lip.
This bottle has a circular depression on the base and dates from the late 19th century. This is not, however, a pontil mark.
An iron pontil mark on the base of a Dr. Townsend's Sarsaparilla bottle. This mark is at times incorrectly called a graphite pontil.
This wine bottle has a deep depression or "kickup" in the base - the pontil ring can be seen in the bottom center.