Estellville Glass Factory
— Estell Manor Park —
Pots were the clay crucibles used as containers in the furnace for melting the raw materials to make glass. Making the pots, the process which took place in this building, was the most exacting work in the entire glass-making industry.
The pots were about two inches thick, thirty inches high, and forty inches wide. Each one could hold 1500 pounds of molten glass, and cost as much as $100 in nineteenth-century dollars to manufacture.
Pot manufacture was done with fastidious care, since a flaw in construction could cause a pot to crack and spill melted glass inside the furnace. When this happened, the furnace had to be slaked, shutting down all production, and a dozen men had to labor for hours to extract the broken pot.
Imported clay from St. Louis, Missouri; Germany or England was preferred for the pots though some South Jersey factories used clay from Newcastle, Delaware. After being formed the moist clay pots were dried from two months to a year.
A few days before a pot was needed it was moved to an area of the Melting Furnace, probably on the west side, nearest the Pot House, for pre-heating.
In the side room of the Melting Furnace, the pot was slowly heated to between 80 and 100 degrees. Next, it was moved into a separate small furnace called the Pot Arch, and heated to the temperature of the main furnace. Finally, it was moved into the main furnace, and the furnace was resealed.
Window glass was made from a mixture of silica sand, lime, and potash recovered from the furnace. The raw materials called a "batch," were dumped into the pot through a small hole in the front of the furnace, and that hole was temporarily plugged. The batch was then left to melt for about twenty-four hours.
The intense heat limited the productive life of a pot to an average of seven weeks.
(Inscription below the image in the upper left) Historic photograph of the pot house.
(Inscription below the image in the center left) Tracking clay for melting pots.
(Inscription below the image in the upper right) Building up a melting pot.
(Inscription below the image in the lower right) Mixing the batch.