CLAYS OF NEW YOEK 799 



The different stages in the manufacture of pottery may be 



grouped as follows: 



-n X- ( Washing 



Jrreparation ■] ° 



( Weathering 



rin chaser mills^ 



„ . ! Wet pans 



lempermg -l 



I Pug mills 



I Tables 

 ['Turning 



Molding \ ° -^^^^ 



Casting 



I Pressing 



Drying 



Burning 



Glazing 



Decorating 



Burning 



Preparation 



In some regions the clay is prepared in a preliminary way by 

 weathering, but this is not a very widespread custom. 



Clays for common earthenware are seldom washed, but those 

 used in the manufacture of stoneware, specially of the higher 

 grades, are frequently prepared in this manner; those clays which 

 are used for white earthenware and porcelain are nearly always 

 washed. 



Clays are washed by one of two methods. With the first method, 

 the clay is thrown into large circular tubs filled with water, in which 

 it is stirred up by revolving arms and the clay lumps thereby dis- 

 integrated. By this treatment the fine kaolinite particles, as well 

 as very fine grains of mica, feldspar and quartz remain suspended 

 in the liquid, while the coarser grains settle on the bottom of the 

 tank. The water with the suspended clay is then drawn off to the 

 settling tanks. 



A modification of this consists in the use of a large cylinder, 

 closed at both ends, which is set in a horizontal position, and con- 



