The Story of Porcelain

by Sara Ware Bassett

"No. For the glazed china we generally use glost saggers that have been covered on the inner side with a coating of enamel."

All this time as they talked they had been passing through the mill and they now entered a low hot building where a series of brick ovens with arching tops covered the floor.

"Here," said Mr. Marwood, "are the firing kilns. After the ware has been brought here in baskets it is very carefully packed in the saggers, and the saggers in turn packed in these great brick ovens. Before they are put in the kilns have to be cooled so the heat to which the ware is subjected may increase gradually."

"But it must take forever to pack all the saggers into the kiln," declared Theo as he viewed in consternation the interior of one of the waiting ovens.

"It takes a long time—about five hours," answered Mr. Marwood. "Porcelain requiring a shorter firing is placed near the front of the kiln, so it can be removed if necessary before the rest is taken out. After the kiln is filled the men brick up the door of the oven and start the fire. There the china bakes from forty to sixty hours. The length of time required depends on the sort of ware being fired and the temperature of the kiln. Then the opening is unsealed and the cooling process begins.

"Do they wait until the saggers and their contents are cold before they take them out?" asked Theo.

"No, indeed," was Mr. Marwood's reply. "That would take too long. Often we are in a hurry to get the goods out and the ovens cooled for the next lot of porcelain; frequently, too, we want the ware so that we may continue work upon it. Therefore we begin the drawing while the oven is still very hot—so hot that the men are stripped to the waist and wear only overalls, shoes, and thick gloves. The kiln drawers are never forced to draw out the saggers, however, when they are intensely hot unless they wish to do so. The law protects such workers and specifies at just what degree of temperature the work is to become optional. Not only do these men draw the ware, but they also empty it from the saggers as well as put it into the baskets in which it is carried back to the factory and inspected, further decorated, or packed for shipping."

Mr. Marwood waited a moment, then added:

"In some foreign countries a tunnel kiln is used instead of an oven like this. It is supposed to require less fuel. It is a long tunnel with a track through the centre over which little cars laden with ware are propelled by machinery. The heat is graded in such a way that it is most intense in the middle of the kiln. The ware starts at one end of this tunnel where the temperature is quite low, travels toward the centre where the heat is highest, and then comes out at the other end of the tunnel through a diminishing heat. In this way it cools gradually. They say, however, that such a method is more successful for biscuit (the unglazed china) than for the glost. Here in America where fuel has always been plenty we have stuck to our old-fashioned brick ovens in spite of their expense. I am afraid we are not a saving nation."

"Father says that after this war is over we shall have to be more saving," said Theo.