During the 19th Century, Rockport was a major supplier of lime to East Coast markets. These kilns converted limestone rock supplied by 15 local quarries into lime used to make mortar & finish plaster. The burned lime was packed into wooden casks and shipped by schooner . In 1843, all 100 lime cargos came from Rockport, Camden, and Thomaston kilns. In 1859, it was a $100,000 industry shipping 156,500 casks. A disastrous fire in 1907 came at a time when cement was beginning to replace lime in building construction. The industry continued for a few more years but never fully recovered.
Built of granite and field stone with interiors lined with fire brick, the kilns were enclosed by great wooden, flat roofed sheds. Some kilns were topped with iron stacks made of boiler plate. Most kilns were wood burning with the exception of the triple "Pets" shown in the drawing. These burned soft coal. All were loaded with limerock at the top from a trestle built along the back. Fires were fed continuously day and night except for a half hour before it was time to "draw" out the kiln every four hours. Partially burned lime was hauled to dumps along the Goose River.
Through the efforts of Mr. Ambrose Cramer, these kilns, the last surviving evidence of Rockport's industrial past, were declared an historic site in 1970.
Under the direction of his widow, Mary Cramer. The lime kiln restoration committee was formed in 1976 in order to restore and stabilize the kilns. In 1983, a matching grant permitted the preservation of the most unusual triple kilns so that the interior can be seen.
Top inset: The railroad brought in limestone (calcium carbonate, CaCO3) from the local quarries which was dumped into the top of the kilns to form a charge.
Middle inset: Heating the limestone breaks the bond between calcium oxide and carbon dioxide to form common or lump lime used to make plaster or mortar.
Bottom Inset: After processing, the lime was put into watertight casks for shipping to Boston and New York markets. Any water coming into contact with the lime could cause a fire aboard ship.
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