The Story of Porcelain Part 21

"Iron?" repeated Theo.

"All clay has metals in it," continued Mr. Marwood. "Should you leave any of these in a pottery clay they would cause you much trouble, for when the ware was fired the metals would melt and discolor your porcelain. Sometimes this happens with cheap chinas. I dare say you yourself have seen dishes that are specked with yellow, or have stains here and there. Sometimes you can also detect bluish particles. That means the cobalt has not been properly ground or sifted. In less expensive wares such defects are frequent. But there is no excuse for them when making fine quality porcelains."

Theo listened attentively.

"After this iron has been extracted," went on Mr. Marwood, "the slip pa.s.ses into smooth agitators, where it is simply kept well stirred in order that the heavier ingredients in it may not settle to the bottom. Then the liquid is forced by means of a slip-pump into the filter-presses, and it is now that you begin to see an approach to the clay used for shaping dishes. Up to this point the slip has been only a thick creamy substance. Now the filter-press squeezes this through canvas bags until after having been pressed between iron plates you get your cakes of smoothly mixed clay of about the consistency of putty. Each cake is of regulation size, and it is supposed to be an inch-and-a-quarter in thickness, and to weigh forty-two pounds."

"The clay is now ready for use?" Theo asked.

"Practically so," was Mr. Marwood's reply, "although before it can be sent to the jiggermen to be modeled it must pa.s.s through the pug-mill to be made more plastic and workable. It is here that it gets its final kneading, all the air bubbles in it being eliminated by a series of steel knives."

"I must say it is pretty thoroughly prepared," smiled Theo.

"It has to be," was Mr. Marwood's grave reply. "Each of these details is an important factor in the making of high grade porcelain, and should any of them be omitted we should get no flawless ware. It was this infinite care in preparing clay that gave to China, j.a.pan, France, and Germany their perfect results in porcelain-making. If we would equal what has been done in the past we must be just as painstaking, and neglect no detail. As a nation we Americans are far too p.r.o.ne to dash ahead and expect results all in a minute. We do not like to mount a stairway step by step; we wish to shoot to the top in an elevator. Now you cannot manufacture porcelain, or for that matter anything else, in such a fashion."

"I know it," replied Theo. "Dad says we hurry so much over the little things that we turn out quant.i.ties of poorly made goods that are just hustled through instead of being carefully finished."

"Your father is right," Mr. Marwood admitted. "It is far too often quant.i.ty and not quality with us. Just so long as men are paid on the piece-work system we shall not better the condition, either. It stands to reason that a man who is rushing to make as many objects of one kind as he possibly can in an hour is not going to take the pains to finish them very carefully. His daily bread depends on his hurrying. Not a second can be lost. It is an unfortunate labor condition, and one that I hope to see remedied some time."

The elder man smiled.

"But we must not take time now to go into labor problems," he added. "In our day they are absorbingly interesting and one might spend hours discussing them. What we all are eager to do is to see them readjusted until they shall be fair to all parties."

"That is what Mr. Croyden wants," put in Theo.

"I know it is. He is heart and soul in this mill and his employees. All the time he is working to improve conditions here. Now we must go on, or we shall not get anywhere. To return, then, to our clay; it is now ready to be carried to the floor above on elevators and handed over to the potters."

"Are the ingredients for the glaze prepared in the same way?" Theo inquired.

"Partially so. The formula for the frit and glaze is also a secret one. Usually the frit, a material similar to gla.s.s, is crushed to powder beneath stone rollers called chasers. Water is then added and the compound turned into the grinding-mill where it is ground for an entire day. Sometimes, however, a different process is preferred and the material is put into a kiln and melted instead. In either case it must finally be worked into a smooth liquid which can be strained through fine lawn. It is then sent to the agitators and constantly stirred until it can be pumped into the storage tanks in the dipping-room."

"That is just what I wanted to know," said Theo.

"Any more questions?"

The boy shook his head.

"Not now, thank you."

"Then as we have finished here shall we go up to the clay-shop?"

"Yes, I am ready," Theo affirmed. Then as if confronted by an afterthought he asked:

"Is the porcelain made here bone china or ----"

"Spar?" put in Mr. Marwood as the lad hesitated.

"I don't think I understand."

"Feldspar."

"Oh, then I know," cried Theo. "I did not realize you cla.s.sified porcelains as bone or spar."

"We do," was the quick reply. "Our finest grade of porcelain has little or no phosphate of calcium, or ground bone, in it. But it is in consequence very costly, and therefore to meet the demands of the market we also manufacture a porcelain slightly strengthened with a bone element. Nevertheless this is composed of such a wonderfully blended body that it is as exquisite as any of the most beautiful English wares. Personally I prefer it to a pure feldspathic china."

"My questions are all answered now," laughed Theo. "Shall we go up to the clay-shop?"

They rang for an elevator and stepped in.

"Next floor, O'Keefe," said Mr. Marwood to the operator. "I am going to teach this lad how to make dishes."

[Ill.u.s.tration]

CHAPTER XVI

DISHES, DISHES EVERYWHERE!

[Ill.u.s.tration]

"Clay," began Mr. Marwood as they went along, "can be shaped in any one of several ways, you know: either by throwing; by turning; by pressing it into hollow moulds; by shaping it by hand over another type of mould; by pressing it into flat ware such as platters and plates; by making it by machinery over moulds as is done by hand; by casting it into the desired form; and by compressing it."

Theo looked puzzled.

"The list sounds like a long one," Mr. Marwood went on smiling into the boy's troubled eyes, "but when you understand the processes you will find that it is all much simpler than it seems. Before we begin to investigate any of these methods, however, I want to say just a word about the moulds over which, or inside of which, the ware is sometimes shaped; for moulds are a very important feature both of pottery and porcelain-making."

"What are the moulds made of?" was Theo's first question.

"I am glad you asked, for that is the vital matter," Mr. Marwood replied. "Many materials have been tried with varying degrees of success--plaster-of-Paris, alabaster, steel, gun-metal, and bra.s.s. Of course what is necessary is a strong, firm, absorbent material. Clay moulds break too easily, and also become saturated with water and lose their shape; metal moulds, on the other hand, while most useful in making wares decorated with fine, raised designs such as the Wedgwood figures, fail to seep up the superfluous water. Therefore plaster-of-Paris has proved the best medium for the purpose. Not only does it retain its form, but it also takes up a certain proportion of the moisture from the clay that is moulded inside or outside it."

"I understand," Theo nodded.

The elevator stopped and they stepped out into a vast, well-lighted room, gray with clay-dust and thronging with powdery workers. At benches, before revolving wheels, and beside turning-lathes toiled busy workmen with white, clay-coated hands.

"We will start our program with the potter's wheel, the oldest of pottery modeling devices," said Mr. Marwood. "It is a very simple contrivance, you see--just a round piece of board set horizontally on top of a revolving spindle. As the disc turns the potter shapes the clay with his fingers, building it up to the desired height and moulding it to conform to the profile, or pattern, he keeps beside him. This profile is of wood or steel, and gives the elevation of the object in actual size. As he works the potter constantly consults and measures it. Pieces made in this fashion are known as thrown ware. All the finest potteries, as well as some of the most expensive porcelains, are made in this way. However, it is a costly process and rather slow, for a piece thus shaped must have the entire attention of a single worker. If we were to make all our china by this method I do not know where we should bring up. It would take us a decade, and cost us a great deal of money. But by this means the most artistic results are obtained. It was in this fashion that the Greeks modeled their matchless vases, and you can now see why no two of them were alike. Each potter put his soul into the thing he was making, and as he had endless time at his command he worked with utmost care to perfect his product. This was all very well in a warm country where life was simple; demands few; and where there was not the tension of present day living. It was a matter of no concern if the artist made only a few such vases in a lifetime. He had the patronage of the rich, and was sure of being taken care of. But to-day, alas, we face a different problem."

[Ill.u.s.tration: "IT IS A COSTLY PROCESS, AND RATHER SLOW"]

"We surely do," agreed Theo.

"Therefore, here in America only a small proportion of this thrown ware is made. Such art potteries as the Roferno and Sicardo wares, seen chiefly in private collections and museums, are thrown; also some of the Grueby, Rookwood, and Cincinnati varieties--all very beautiful American potteries. In addition to these exquisite home products The Dedham and Paul Revere potteries made near Boston should be mentioned, for although of less costly type they are doing much to set a standard of perfection of form, choiceness of coloring, and fitness of design. All these wares are distinct contributions to the art world. Of course certain wares are made by a modification of this throwing process. Large pieces, for example, frequently have to be thrown in several parts, fastened together, and afterward finished. Some pieces the thrower shapes over a plaster-of-Paris mould; and some he shapes inside the mould, reversing the process and pressing the clay against its confining surface. The danger in thrown ware comes from an uneven pressure on the clay resulting in a lack of solidity; the pieces are not always equally firm at all points and in consequence sometimes crack."

"Can pieces of any design be thrown?" inquired Theo.

"No, only round pieces such as cups, mugs, vases, jars, or bowls. In other words, only circular pieces. Frequently, too, these are only started by the throwing process and are finished by some other means such as turning, for example."