The Melting Furnace

The Melting Furnace was the heart of the glassworks. Here the silica sand, lime, and potash were melted into glass.

The furnace was at the center of the building. Before use, wood was dried and stored in the northeast corner of the building. The fire of the furnace was stoked with wood by men standing in the stoke pits below floor level, on the east and west sides. The fire was intense, with a powerful draft. A glassblower at a plant in Clayton recalled seeing a man sit down to eat a sandwich, only to have it whisked out of his hands and up the chimney.

The raw material had to be prepared before being mixed. The sand was dried and heated in sand kilns, probably in the southeast corner of the building. The lime was prepared in the lime kiln, located south of the Flattening House. The potash was removed from the furnace after firing s and stored until used. The materials were mixed to form the batch as they were needed.

The batch was melted in pots placed on a masonry platform above the fire in the furnace, called the “siege”. Wooden platforms referred to as “benches” were built on the north and south sides of the furnace; these provided access to the molten glass inside the furnace, and gave the glassblowers elevated stations from which to work.

The Gatherer , Glassblowing was team effort which took fast coordinated action, practiced skill and great strength. The “gatherer” started the process by thrusting 5 foot long, 30 pound iron blowpipe into the furnace and collecting a 50 to 70 pound glob of melted glass called “metal”. The only protection the gatherer had from the ferocious heat was a wooden mask, with eye slits fitted with blue or amber glass, which he held in place by gripping a mouthpiece with his teeth. The gatherer fanned the molten glass into a solid cylinder by using a wooden mold, and then handed that blowpipe to the glassblower or gaffer.

The Glassblower , The glassblowers were master craftsmen, who took great pride in their work. They needed the strength to wield the 100 pounds of blowpipe and molten glass, and the skill to turn the glob of glass into a cylinder ten inches across and five feet long, with sides a uniform thickness of 1/8 inch, all within five to ten minutes.

This feat was performed as the glassblower stood on the elevated bench, working over the swing pit, which was about three feet deeper than the floor level. The cylinder was formed through a combination of blowing through the pipe, and swinging it over the pit to elongate the piece of glass through centrifugal force.

Some glassblowers chained themselves to posts to counteract the weight of the glass. Others disdained such precautions, and put themselves in serious danger, sometimes losing their balance and falling into the swing pit covered with hot, broken glass.

When the wall of the cylinder was a uniform thickness the cylinder was removed from the blowpipe and prepared for annealing and flattening.

The blowers of window glass cylinders were regarded as the masters of glassblowing. The five-foot long cylinders could tolerate a few imperfections, unlike the less critical bottle glass. A glassblower was paid not according to how many cylinders he blew, but according to how many boxes of usable glass were cut from his cylinders, he was not compensated for imperfections and thickness out of tolerance.