How Do People Create Glass Objects?

People have been using glass since before we were people – early hominins made small tools out of a volcanic glass called obsidian all over East Africa, specifically the Olduvai Gorge, as far back as 1.7 million years BP. In fact, people in extremely rural areas all over the European and Eurasian subcontinent still make tools out of obsidian to this day. Even modern medicine is getting back into this natural glass – studies have shown that a scalpel with an obsidian edge is so fine and so sharp that it actually cuts between cell walls, making cuts extremely accurate and healing time way faster. But that’s volcanic glass, and we’re talking about knapping – chipping pieces off a block and then chipping away at that piece until you have the desires shape and edges of the tool you need.

The Roman historian Pliny claims that the Phoenicians were the first to actually make glass around 7000 years BP, but the oldest glass vessels and decorative objects actually found date around 1500 years after that. These were typically made via core-forming. And the first blown glass objects don’t show up in the archaeological record until 2500 years BP in India in the form of beads. 400 years later, small tubes and bottles in Israel look a lot like someone figured out you could inflate molten glass into a shape and began experimenting with it. Since this was about the time the Roman Empire rose to prominence, glass blowing technology spread and advanced quickly.

Fast forward to 17th century Italy, when mold-blowing and casting were used to make fancy glass wares and flat glass panes for windows, respectively.

Fast forward again to the late 19th century: the dawn of art glass. Art glass is defined as glass objects made as sculptures. They’re decorative art pieces and serve no utilitarian purpose. This movement eventually spurred the use of art glass pieces for awards and trophies. Since the mid-20th century, it’s become a pretty big deal. But how are art glass awards made? In what ways can glass be blown or shaped?

Different Ways to Shape and Sculpt Glass

Glass has some really unique properties that make it extremely easy to shape and mold into almost anything. It’s not a solid but it’s not a liquid; it’s an amorphous solid – somewhere in between. Superheated sand mixed with a temper form a thick liquid that can be shaped and molded to different degrees at different heats. Then, it’s left to cool and harden. There are several ways to make art glass. Here are a few:

  • Glass Blowing: Blown glass can be free blown, hand blown or mold blown, and involves having a chunk of molten glass (called a gather) at one end of a tube and blowing air through the tube to inflate the glass into a shape. The glass blower then turns, swings and repeatedly reheats the glass until it’s the right shape. Today, this process can be done by a machine as well.
  • Core-Forming: This is the oldest method for making glass vessels (cups, vases, bowls, etc.), and is done by pouring molten glass over a form and leaving it to cool.
  • Casting: This method uses a closed mold the glass-maker pours molten glass into. It was often used to make flat panes for early windows. Think of cast iron; it’s a very similar process.
  • Glass Cutting: The Romans used casting and cutting to fit glass into windows. If you’ve ever broken a window and needed a new pane cut to the right dimensions, you know how this works.
  • Art Glass Techniques: Art glass pieces are made in several ways. Focusing on solid art glass objects, there are typically three different methods of heating and shaping art glass awards:
    • Cold Glass Technique: This method doesn’t require heating. The glass is essentially chipped, sandblasted or etched away.
    • Warm Glass Technique: This method is also referred to as kiln-formed glass because glass is heated in an oven and melted into the desired shape.
    • Hot Glass Technique: Art glass pieces and art glass awards created with this method are made in a similar way to blowing, in that a pipe and a gathering of molten glass are twisted and shaped into the desired form.

See? There’s a lot more to art glass than you thought.