THE PRODUCTS OF CLAY AND FIRE 



to edge one upon the other, to keep them straight; 

 while large dishes of any depth, which are likely to 

 become crooked, are bedded in sand. Pieces having 

 covers, such as sugar-bowls, are fired with the covers 

 in place. If fired separately in different parts of the 

 oven, the variation in heat might cause unequal con- 

 traction so that they would no longer fit. 



Each sagger as it is placed in the bung forms a 

 cover to the one just beneath. In some potteries sand 

 is rubbed between the joints to make them air-tight, 

 but probably a better method is to "wad" the saggers 

 with clay, thin rolls of fire-clay being placed around the 

 edge of the sagger so that the one next above it, press- 

 ing upon the clay, makes the chamber air-tight. The 

 ware in such air-tight saggers must be very dry, how- 

 ever, as otherwise the steam generated and confined in 

 the sagger would "mortar" the ware, which would be 

 found as a shapeless lump of burnt clay when the sagger 

 is opened. 



Where the pieces to be fired are of irregular shape, 

 or are too deep to be placed one above another in the 

 saggers, much waste space is left about them. The 

 economical potter, however, is careful to see that all 

 such spaces of any considerable size are utilized. In 

 the deep dishes, such as large bowls, he places smaller 

 dishes; while in other nooks and corners he places 

 all manner of small clay objects. It is a very small 

 space indeed that will not hold such small objects as the 

 many-shaped insulators used by electricians. And as 

 there are from twenty-five hundred to three thousand 

 saggers in the ordinary- sized oven, it will be seen that 



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