The pontil, or punty, is a solid metal rod that is usually tipped with a wad of hot glass, then applied to the base of a vessel to hold it during manufacture. It often leaves an irregular or ring-shaped scar on the base when removed. This is called the “pontil mark.”

What does a pontil mark look like on a bottle?

Before 1855, most bottles displayed an open “pontil mark” on the base of the bottle. Glassblowers used an iron punty rod to hold the bottle. They would secure the punty rod to the bottom of the bottle. The rough-looking open pontil mark, or pontil scar, looks like an irregular, colorless hole in the bottles base.

What do the markings on the bottom of bottles mean?

Many bottles carry only a number (or numbers) on the base. These marks usually served as some type of mold identification, indicating a particular mold used by a glass factory. If a number of identical molds were produced for making a certain type of bottle, they would often be serially numbered (such as 1 to 12).

How do you tell if glass is blown or molded?

Tiny Bubbles Bubbles can appear in both blown and molded glass vases. Bubbles in blown glass will not be consistent in color or size. Blown glass will also capture various strands of colors. Bubbles and colors in molded glass will appear more uniform.

Should hand-blown glass have bubbles?

Many hand-blown glass objects contain small air bubbles inside the glass. Some glassblowing studios promote air bubbles as an aesthetic feature of their pieces. However, machine-produced glass objects can also contain bubbles, so this characteristic is not unique to hand-blown glass.

What are the bubbles in blown glass called?

The Italian name for the kind of glass with random bubbles is pulegoso. Single bubbles may be pushed into molten glass with a spike, making an internal sphere which looks silvered when the glass cools.