The Story of Porcelain Part 22

"What is turning?" asked Theo.

"Surely you have seen a turning-lathe, Theo," a.s.serted Mr. Marwood. "Here is a turner just opposite us. You will notice he has a lathe that goes by steam. The vase on which he is working has previously been roughly formed on a jigger--a revolving mould over which a sheet of clay has been pressed and quickly shaped. After such a piece has been dried to a leather hardness the turner takes it in its crude and uncompleted state and by running his lathe over it planes down the surface to a smooth, even thickness. Sometimes, too, by means of one of these lathes milling-tools are used to cut designs around the neck or base of the article. The rough edges are then sponged and before the piece is thoroughly dried handles are put on if desired. Here in America turning is the process very generally employed for finis.h.i.+ng articles begun by the jiggermen."

"And now about hollow ware--how do they make that?"

"Hollow ware is pressed by hand," answered Mr. Marwood. "The process is used for pieces that cannot successfully be made by any other means--such things, for example, as soup-tureens and large covered dishes. The idea is to press the clay over or into moulds so it will be the exact shape required. Of course this necessitates the making of pieces in sections. The two sides of a vase are moulded separately, for instance; also the bottom. Then the parts are pressed firmly together and held in place by strings or thongs of leather until securely joined. Afterward the base is inserted in its proper place. The inside seams are then leveled and sponged away, and the mould sent to the drying room. Later it is returned; the outside seams moistened and smoothed; the moulded handles put on; and the piece is ready to be decorated and fired. It is a difficult ware to make, for unless the workmen are skilled at giving the clay an even pressure it is liable to be thicker in some places than others. Sometimes, too, if the seams are not strongly united the article will crack. It demands a strong, even touch. Remember that hollow ware is pressed from the outside; and that flat ware is just the opposite, and is pressed from the inside. The top surfaces of such things as plates, platters and trays are thus formed, their outer side being shaped by hand or by a jolly, which we shall see presently."

Mr. Marwood pa.s.sed on through the crowded room until he suddenly paused beside a workman at another machine.

"This," explained Theo's conductor, "is a jigger. There are two machines very commonly used in the United States for shaping the cheaper wares: one is a jigger, a device of this type; and the other a jolly, an invention very similar in construction but having a tool attached that forms the outside, or bottom of the piece, the inside of which has previously been shaped by the jigger. You may recall that I spoke of the jigger; and told you how a revolving mould was inserted into it, and how afterward a sheet of clay was laid on the outside of this mould and rapidly shaped. The jolly, on the other hand, is used for making such things as covers, the top surface of which has already been moulded. The profile set in the jolly-lever makes the bottom. That, as I told you, is how we get the base of our plates. For certain articles the jigger is preferred; for certain others the jolly; but the aim of both is the same, and the workers at the machines are all called jiggermen. After an article is taken from the jigger or jolly it is dried and carried to the turning-lathe to have its surface smoothed and finished."

"And does it take all these men to run a jigger?" whispered Theo, pointing to the moving figures that hurried to and fro.

"An organized group of men is employed at each machine," answered Mr. Marwood. "First there is the _clay-carrier_, who must bring the material to the workmen; then there is a second man called the _batter-out_ who takes from the carrier the piece of clay cut into the proper size, and after laying this on a block gives it a strong blow with a plaster-of-Paris bat to flatten it for the jiggerman. When making simple objects such a man can give the article quite a start even with one stroke. You can see that some such beginning must be made before the jiggermen can handle the material."

"How much does the bat weigh?" demanded Theo, instantly interested.

"About fifteen pounds. It is not very heavy, but the batter wields it with considerable force. After the article has thus been approximately shaped, and the jiggerman has completed it, a mould-runner must carry the freshly modeled piece to the stove-room to be dried; and on his backward trip bring with him two other articles that are already dry. These he takes off the moulds, leaving the dry piece to go to the finisher, and the mould to the batter-out. The fourth man in the team, or crew, is the _finisher_. His duty is to smooth the rough edges of each article with a damp sponge, or a tool of flat steel. After this process is completed the jiggerman's crew is through with its part of the work and the goods go to the greenroom to be counted, and if perfect accepted by the foreman. Most jiggermen hire their own helpers, as it is simpler for them to do so. Formerly only round articles were made by the jiggermen--such things as cups, plates, bowls, etc. But now oval, as well as round dishes, can be made on a jigger, although elliptical wares are not turned out this way to any very great extent, other processes of shaping being preferred for objects of this type."

"You spoke, Mr. Marwood, of casting some wares," remarked Theo.

The older man smiled.

"You have a good memory, my boy," he said. "I did mention casting. It is an independent process, and shapes of great variety can be fas.h.i.+oned as well as ornamented in this way. By the casting method, too, we are certain of getting articles of uniform thickness. We can even make very thin objects by this means. But the process is destructive of moulds, and therefore has its flaws. The success of the plan is entirely dependent on the mould's absorption of the moisture in the clay; otherwise the method of casting could not be applied to potteries or porcelains. As the clay is compressed the water is squeezed out of it, and this the mould must take up, or the clay would never dry and retain its shape. You can understand that, I think."

"Yes, sir."

"The last of the processes of which I wish to tell you is die-pressing. Here we take a very finely ground clay dust; moisten it a little; and fill a die, or steel mould, with it. This die we then put into a screw, or hydraulic press, and squeeze it under an intense pressure with the result that the piece is shaped very solidly. We use this process for making small, complicated objects such as those employed for electrical purposes. They are brittle and delicate and have to be manufactured with extreme care."

"Are plumbing supplies made this way?"

"No, indeed! Sanitary pieces are too large to be turned out in such a fas.h.i.+on. They are made by hand, being first built up inside enormous moulds. We can employ only the most skilful workmen on this task because the goods are difficult to make. Such a thing as a porcelain bath-tub involves a great deal of clay, and therefore were it to be damaged we should lose much expensive material." Mr. Marwood took out his watch. "Now, there you have all the various ways of shaping clay ware! Its decoration and firing is another story, and far too long a one for us to attack to-day. We must be back at the conservatory at one o'clock for luncheon. Evidently Mr. Croyden got too deeply snowed under to join us, so we shall have to hunt him up. Confess you are hungry."

Theo's eyes twinkled.

"I believe I could eat something if I were urged," he admitted.

"So could I," rejoined Mr. Marwood heartily. "I am starved. We will find Mr. Croyden right away. It has been a good morning, hasn't it, Theo?"

"Certainly I've enjoyed it," exclaimed Theo.

"And I too," agreed the older man.

[Ill.u.s.tration]

CHAPTER XVII

THE DECORATION OF CHINA

[Ill.u.s.tration]

Next morning bright and early Theo and Mr. Croyden were off to the factory, and once more the boy found himself consigned to the care of Mr. Marwood. This was no hards.h.i.+p, however, for the two got on excellently together, and Theo was only too glad to cooperate in any way he could with Mr. Croyden, whom he knew to be very busy. Therefore with this new friend as pilot the pilgrimage through the china works was resumed at precisely the point where it had been left the preceding day.

"This morning," Mr. Marwood said, "we will turn our attention to the decoration of porcelain, which I think you will find quite as interesting as was its making. There are almost as many different processes to decorate the ware as there were methods of shaping it."

"Which one are we to begin with?" questioned Theo eagerly.

"I think we'd better start with printed designs. Were you ever in Was.h.i.+ngton, Theo?"

Theo glanced up in surprise at the irrelevance of the inquiry.

"Yes, sir."

"Good! What were some of the places you visited?"

Again the lad regarded his conductor curiously.

What had his trip to Was.h.i.+ngton to do with the decoration of china, he wondered.

"Oh, I went to the Capitol, of course," he answered, "and to the White House, and the Congressional Library; then Dad took me to the Smithsonian Inst.i.tute and to the Bureau of Printing and Engraving, and ----"

"Stop!" cried Mr. Marwood. "I now have found out exactly what I wished to know. So you have seen bank notes engraved?"

"Yes, sir."

"You remember then how the design is cut on a copper or steel plate?"

"Yes, indeed," came promptly from Theo.

"I am very glad of that, for it is precisely this method we use when we print designs on china. The difference is that the designs on our money are printed in ink, and those we transfer to our porcelain are done with mineral colors; nor are our plates so finely made. However, the idea underlying the processes is identical. The color is applied to the metal plate, and what is not retained in the engraved depressions of the design is carefully sc.r.a.ped away. Then on a kind of paper expressly prepared for the purpose the picture is made, and while it is moist it is placed against the ware and rubbed in with a piece of soft flannel. When it is awkward to handle the design as a whole it is cut into sections and pieced together on the china itself."

"Does one person do the whole thing?"

"No. It is the duty of one worker to arrange the design and see that it is in the right place; and the task of the next one to rub it in with the flannel and soap. Then after the china has stood for some time it is put into water and the paper sticking to it is floated off, leaving the colored print on the porcelain."

"Is it done before the ware is fired?" asked Theo.

"Sometimes it is done on the biscuit ware before it is glazed, and sometimes on the glaze itself. It all depends on the result the decorators wish to obtain. If printed before the porcelain is glazed it is called under-glaze printed ware, and must be put through a kiln, which will take the oils out of the print; if done on the glaze it is fired in order to burn the colors in and blend them with the frit."

"It must be hard always to get the designs where you want them,"

observed Theo meditatively. "I used to trace patterns at school sometimes, and often they slipped and made the s.p.a.cing wrong."