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NEW YORK STATE MUSEUM 



while a mixture of the two clays gives a speckled product, and 

 the red clay alone, a red product. 



New York Architectural Terra Cotta Company. The works of 

 this company are situated at Kavenswood, Long Island city. 

 They use clays from both Long Island and New Jersey for the 

 manufacture of terra cotta. The Long Island clay is obtained 

 from Great Neck, L. I. It produces a ware . of light yellow 

 color. Coal was formerly used for burning the ware, but oil is 

 now used instead. It is found that 100 gallons of oil is equal to 

 one ton of coal. The advantage of oil is a saving of labor and 

 time, and it is also more convenient and cleaner to use. 



The Manufacture of Terra Cotta 



In order to produce a good quality of terra cotta, a clay should 

 not whitewash; it should not shrink over one inch per ft. in 

 burning, and should do so evenly; the shrinkage can be regu- 

 lated by the addition of "grog," (pulverized brick, or sand). 

 Clays which are too sandy can be washed ; this is done by 

 dumping them into a circular trough filled with water, in which 

 there revolve paddles fastened to a vertical axis in the center of 

 the trough ; from the trough, launders run to settling vats. 



The motion of the paddles drives the water with the 

 suspended particles of clay into the launder, down which it flows 

 to the vats, while the coarse sand remains behind in the trough; 

 after the clay has settled in the vats, the water is drawn off ; 

 this is the method followed at Glens Falls. Before molding the 

 clay, it should be thoroughly pugged, or, in other words, mixed, 

 and after this the mass should be piled up and allowed to 

 " cure," that is to say, it settles by its own weight, becoming 

 denser while the excess of water evaporates. 



The clay is next molded either by machine or by hand ; the 

 former method is used for plain forms, while the latter is used 

 for ornamental styles of terra cotta. 



Hand molding is of course slower, more difficult, and requires 

 more care ; plaster molds are used, and the clay is forced into all 

 the corners with the hand or fingers. 



The form is then allowed to remain in the mold until it has dried 

 and shrunk sufficiently to drop out of it, or to permit the mold 



