804 NEW YORK STATE MUSEUM ^n, . 



"wHch may be present. A wet pan will grind a cliarge of clay in 

 about 10 minutes. 



Pug mills. Those used in pottery manufacture consist of an 

 upright rectangular box, in which revolves a vertical shaft, bearing 

 iron blades. The clay is charged at the top, and is slowly forced 

 downward to the opening at the bottom of the box, at the same 

 time going through a thorough mixing action. 



Molding 



Pottery is molded in four different ways, turning, jollying, 

 casting, and pressing. 



The clay after coming from the presses, is first wedged, that is 

 a lump of the desired size is cut in two by a wire, the twO' halves' 

 united by bringing them down on the table with much force, the 

 piece cut again, the two halves once more united, and so on, the 

 object being to subject the clay to a kneading action, whereby all 

 the air bubbles are eliminated. 



This operation is accomplished in many European factories by 

 a kneading machine, which consists of a circular table about 6 feet 

 in diameter, whose upper surface slopes outward. On this are two 

 conical rolls, 20 to 30 inches in diameter and about 8 inches wide. 

 These rolls have corrugated rims, and are attached to opposite ends 

 on a horizontal axis, having a slight vertical play. The clay is laid 

 on the table and as the rolls travel around on it the clay is spread 

 out into a broad band. A second axle carries two other pairs of 

 rolls of the same shape but smaller size, which travel around in a 

 horizontal plane. These rolls press the band of clay together again. 

 In this way the clay is subjected to alternating vertical and lateral 

 pressure and all air spaces are thus thoroughly closed. The rolls 

 make 10 to 12 revolutions a minute, and a machine kneads two to 

 three charges of 350 pounds each in an hour. 



Turning. This is done on a rapidly revolving horizontal wheel. 

 The potter takes the lump of clay, places it on the revolving disk, 

 and, after wetting the surface with a slip of clay and water, gradu- 



