The view from inside the furnace

Hot Glass Demonstrations at The Corning Museum of Glass offer a unique view of glassmaking that cannot be seen anywhere else—inside the furnace.

So, how did we put a camera inside the furnace? The history begins with Steuben, where the factory floor, adjacent to the Museum, was an inspiration in the development of the Museum’s own Hot Glass Demonstrations. A former designer for Steuben and now the Museum’s senior director of creative services and marketing, Robert Cassetti, proposed the idea for a camera view of inside the reheating furnace after walking on the production floor of the Steuben factory. The reheating chambers that the gaffers worked at while creating pieces of Steuben’s lead crystal art were large furnaces with several openings around all sides, so multiple people could work from the same furnace at once. If two gaffers were working on opposite sides of the furnace, there were moments when you could look directly through the hole on one side and see the piece being made at the opposite side.

The idea of a view through the furnace from the opposite side of the gaffer was part of the design of the Museum’s first live glassmaking demonstration. Steve Gibbs, the museum’s current senior manager of Hot Glass Programs, and a former gaffer at Steuben worked on creating that view for our visitors, alongside Fred Metz of Spiral Arts, a glass equipment maker. The problem was not about cutting a hole in a furnace, rather, it was about separating the heat on the inside of the furnace from the outside where a camera would be placed to view inside the furnace. The solution came in an innovation developed by Corning Glass Works (now Corning Incorporated) called fused silica. The camera behind the reheating furnace is protected by a sheet of fused silica glass and cooled with a stream of air. Fused silica is a high-temperature/low-expansion glass developed in 1930. It is made up only of chemically rendered silica and melts at 3,800°F, and can easily withstand the 2,300°F heat of the furnace.

The cameras that are used for this view are Sony and Marshall brand compact broadcast cameras. This allows them to fit in the space confinements in and around the equipment but still maintain a high-quality, high-definition image. The camera exposure is set manually because the cameras will try to adjust in auto exposure mode as the doors of the furnace are open and closed. The cameras are also focused manually as the same issue occurs when the doors are open the cameras will try to focus outside of the furnace. The brightness from the heat of the furnace allows the cameras to have a small aperture and therefore a wide depth of field to keep the glass in focus while it’s inside the furnace. The cameras are also in close proximity to the furnace to give the widest view possible of the inside and, therefore, the best view of the glass. This is why the fused silica window and its high temperature properties are so important to this unique view.

There is a camera for each furnace in the Amphitheater Hot Shop which shows a high-definition view inside the reheating furnace. The largest furnace is 32 inches in diameter and allows our gaffers and guest artists to work at an impressive scale heretofore not seen in our live demonstrations. And, thanks to the cameras and specialty glass, they can be seen from every angle during the making process.

This view has even inspired creativity from Guest Artists in what they choose to create when working in the Museum’s Hot Shops. Karen Willenbrink-Johnsen was a recent Guest Artist who demonstrated in the Amphitheater Hot Shop this past June. She created a glass rabbit holding a carrot, and the furnace camera provided a unique view of her character in the making.

One of the most fascinating things about the Museum is the way it is able to change someone’s perspective about glass. Museum guests get to see a piece of glass art being made right before their eyes, and it gives them a glimpse into a material they probably use every day, but have not thought much about. The furnace cameras help add that unique view of the process of glassmaking.

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Watch past Guest Artist demos on the Museum’s YouTube Channel.
And see a Hot Glass Demonstration live at the Museum every day.