The Story of Glass Part 13

Mr. Wyman welcomed them cordially.

"We see many visitors here, sir," said he, "and are always glad to have them come. Although gla.s.s-making is an old story to us scarce a day pa.s.ses that some one does not visit us to whom the process is entirely new; and it certainly is interesting if a person has never seen it.

Suppose we begin at the very beginning. In this bin, or trough, you will see the mixture or batch of which the gla.s.s is made. It is composed of red lead and the finest of white beach sand. The lead is what gives the inside of the trough its vermilion color. The sand comes from abroad, and before it can be used it must be sifted and sifted through a series of closely woven cloths until it is smooth and fine as powder. Before we put the mixture into the melting pots we heat it to a given temperature so that it will be less likely to chill the clay pots and break them."

"Do you really make gla.s.s by melting up that stuff?" asked Jean incredulously.

The man smiled.

"But isn't it all red?"

"The red comes out in the melting. We have to be very careful, however, in weighing out the ingredients, for much of our success depends on the accurate proportions of the materials combined in the batch. Of course the chemical composition differs some for different sorts of gla.s.s. It all depends on what kind of gla.s.s is to be made. Then too the conditions of the furnaces vary at times, the draughts being better at some seasons than at others. We take a test or proof of every fresh melt, and you would be surprised to see how little these differ.

Careful mixing of the raw materials is the first important item of successful gla.s.s-making; the second is the fusion by heat of the materials."

"The batch is next melted, Jean," explained Giusippe, as they followed Mr. Wyman into the great brick-paved room where the furnaces were.

Here indeed was a picturesque scene. Numberless men were hurrying hither and thither, some whirling in the air glowing ma.s.ses of molten gla.s.s; others standing before the furnace doors gathering b.a.l.l.s of it on the end of long iron blow-pipes which were from six to nine feet in length. Everybody was scurrying. As soon as a ball of red-hot gla.s.s had been collected on the end of a blow-pipe it was rushed off to the blower before it cooled. In and out of the throng of moving workmen young boys, or carriers, swung along bearing to the annealing ovens on charred wooden trays or forks newly completed vases or pitchers.

Jean glanced about, fascinated by the bustling crowd.

"Here are the furnaces," the foreman said. "Each one has twelve openings and is built with a low dome to keep in the heat. The flues or chimneys are in the sides of the furnace. Within, and just beneath the openings or working-holes, stand the great clay pots of molten batch.

These pots are made for us from New Jersey clay; formerly we used to make them ourselves, but it was a great deal of trouble, and we now find it simpler to buy them. They vary in cost from thirty to seventy-five dollars, according to their size."

"And they are liable to break the first time they are used," whispered Giusippe in a jesting undertone.

Mr. Wyman caught his words.

"Ah, you know something of gla.s.s-making then, my young man?"

"A little."

"The pots are, as you say, a great lottery. Sometimes one will be in constant use three months or longer, and do good service; on the other hand a pot may break the first time using and let all the melt into the furnace. Then we have a lively time, I can tell you, ladling it out, and taking care in the meantime that none of the other pots are upset."

Giusippe nodded appreciatively.

Many a day just such a catastrophe had occurred when he had been working; vividly he recalled how all the men had been forced to come to the rescue.

"Are the pots filled to the top with batch?" asked Mr. Cabot.

"Yes, we charge them pretty solid; but the raw material loses bulk in melting, so they have to be filled in as the melt settles. At the end of ten or twelve hours we have a refilling or _topping out_, as we call it; usually this is enough. The first fill must become fluid and its gases must escape before any more material is added; we also have to be sure when we put the pots in the furnace that the temperature is high enough to melt the batch immediately, or the gla.s.s will go bad."

"What do you use for fuel?"

"Crude oil. In the West they can get natural gas, and there they often melt the batch in tanks instead of pots. But we find crude oil quite satisfactory. You can readily understand that we cannot burn any fuel that gives off a waste product such as coal dust or cinders, because if we did such matter would get into the melt and speck the gla.s.s, causing it to be imperfect. Much of the work done by the earliest gla.s.s-makers was specked in this way, and in fact the genuineness of old gla.s.s is sometimes determined from these very imperfections."

"I see," Mr. Cabot nodded.

"After the melt is in a fluid state it throws to the top, provided the heat is sufficient, many impurities such as bubbles and sc.u.m. These are, of course, skimmed off--a process called plaining. Afterward the hot material has to be cooled before it can be worked, and reduced from fluid to a thicker consistency. This we call _standing off_ or _fining_."

"How long does it take to melt the batch and get it ready to use?"

"About three days. We run a relay of furnaces--three of them--and plan so that a melt will be ready to be worked every other day; in that way we keep plenty of usable material on hand."

"And then?"

"Then we are ready to go ahead and blow it. We make nothing but the better grades of blown gla.s.s here; that is, no window gla.s.s or cheap pressed ware. Of course there are some patterns, such as fluted designs and their like, which cannot be entirely fashioned by the blower; therefore these are first blown as nearly the required size as possible and are then made into the desired form by shutting them inside iron moulds and squeezing them into the proper shape. You shall see it done later on."

He now led them up to where a gatherer stood at one of the working-holes of the furnace.

"This man," explained Mr. Wyman, "is collecting on his blow-pipe enough gla.s.s to make a pitcher. He uses his judgment as to the amount necessary, but so often has he estimated it that he seldom gets either too much or too little. He will next carry it to the blower, who will blow it into a long, pear-shaped cylinder the size he wants the pitcher to be."

They followed, and with much interest watched a great Swede fill his lungs and blow into the smaller end of the iron pipe with all his strength; immediately the ball of soft, red-hot gla.s.s began to take form. With incredible speed the blower flattened its base upon a marver or table topped with sheet iron. A short iron rod or pontil was next fastened to the middle of the bottom of the pitcher in order that the blower might hold it, and after this had been done the blow-pipe was detached. The gla.s.s-maker sat in a sort of backless chair which had long, flat, metal-covered arms at either side, and as he worked he rolled the rod with its plastic material back and forth along one of these iron arms to shape it. He then took his shears and, making an incision at the middle of the back of the jug, he began to cut the top into the shape he wanted it, depending entirely on his eye for the outline. Then quick as a flash he seized a bit of round metal not unlike a beet in shape and, pressing it inside the soft gla.s.s, made the depression for the nose. All this was done in much less time than it takes to tell it. A small boy, or carrier, now bobbed up at just the proper moment and taking the pitcher on his wooden fork carried it off to a small furnace where it was reheated at the opening or "glory hole." This little furnace, Mr. Wyman said, was used only for the purpose of softening gla.s.s objects which became chilled in the modeling and began to be hard and less pliable. As soon as the boy brought the pitcher back another lad, as if calculating by magic the precise moment at which to appear, approached with a small ma.s.s of molten gla.s.s at the end of his gathering-iron. This he stuck firmly against the pitcher at the correct spot to form the base of the handle; the modeler snipped off with his shears as much of the soft gla.s.s as he thought necessary, turned it up, and in the twinkling of an eye fastened the upper end of the handle in place. Then he surveyed his handiwork an instant to make sure that it was symmetrical, straightened it just a shade with his battledore of charred wood, and pa.s.sed it over to the carrier, who bore it off to be baked.

"Why do they use so much charred wood for the shaping?" inquired Jean.

"Metal things are liable to mark the gla.s.s, leaving upon it a print, scratch, or other imperfection; charred wood, when worn down, is absolutely smooth and cannot mar the material."

"Oh, yes, I see. And where have they taken the pitcher now?"

"We will follow it," replied the foreman.

Escorting them across the room he showed them a low oven or kiln. The door of it was open, and inside they could see all sorts of gla.s.sware which had just been finished.

"Here is where your pitcher will remain for the next three days," said he. "We build a fire, put the completed gla.s.s in the oven, and leave it there until the fire goes out and the oven gradually cools; we call the process annealing. It prevents the gla.s.s from breaking when exposed to friction or to the atmosphere. Gla.s.s is very brittle, and extremely sensitive to heat and cold. If it were not annealed it would not be strong, and would snap to pieces the moment it came in contact with the outer air. Now it is very difficult to anneal gla.s.s, the trouble being that all hollow ware is one temperature on the inside and another on the outside. Hence, when heated, the inside takes longer to cool. Any current of cold air that strikes it will fracture it. So, as you can readily see, an annealing kiln or oven must be arranged in such a way that it will allow the two surfaces to cool simultaneously."

"I think I understand," answered Jean. "And you say these things must stay in the kiln about three days?"

"Yes, the kiln takes about that time. It is a slow process, because we have practically no way of regulating its heat. A lehr does the work much quicker. Over here you will see one. It is a long arch or oven open at both ends. The gla.s.sware travels in iron pans along a moving surface from the hot oven, or receiving end, to the cool, or discharging end. The temperature of the lehr can be scientifically tested and regulated, and this is very necessary, because the heavy gla.s.s intended for cutting can stand a greater heat than can ordinary hollow ware such as vials and table gla.s.s. We regulate the oven according to what we are annealing in it. It does not take so long to anneal gla.s.s in a lehr as in a kiln, and therefore in many factories only lehrs are used. If you will come around to the cool end you can see some of the finished pieces being taken out. Each object is made by a certain set or gang of workmen--a shop, we call it. The work of each shop when taken from the lehr is put in a box by itself and is then counted up, and the men paid according to the number of perfect objects finished. It is piece work. For instance, one shop makes only pitchers, another wine-gla.s.ses, another vases, and so on. Every group has its specialty, and each workman in the team understands exactly what his part is in the whole. The common interest of turning out as many perfect pieces as possible spurs each man to work as rapidly, well, and helpfully as he can."

"Just like a football squad, Uncle Bob," laughed Jean.

"Exactly," nodded Mr. Wyman. "After the finished gla.s.s is taken from the kiln or lehr it goes to the examining room, where girls dip it in clear water and hold it to the light to test it for imperfections; then it is sorted, packed, and shipped."

"And vases, sugar-bowls, tumblers, and most of the hollow gla.s.sware is made in the same way?" inquired Mr. Cabot.

"Yes, practically so. The general scheme is the same. As I told you, there are some difficult designs which must be squeezed into shape in moulds. These are of iron, and for the convenience of the blowers are set in holes in the floor. They are made in two parts joined by a hinge. The molten gla.s.s is blown to the approximate size and then a boy shuts it inside the mould and the blower blows into it until it has entirely filled out the mould in which it is confined. When released it is shaped to the form required."

[Ill.u.s.tration: "IT IS SHAPED TO THE FORM REQUIRED"]

"But doesn't it stick to the mould?"

"Seldom. The moulds are painted over on the inside with a preparation which prevents the gla.s.s from sticking."

"Do you cut any gla.s.s here?"

"Oh, yes. Cut gla.s.s is made from the heavier crystal variety. The design is roughly outlined upon it in white and then the cutter places the part to be cut against an emery-wheel, which grinds out the grooves and figures and makes the pattern. Just above each cutter's revolving wheel is suspended a funnel of wet sand, and this drops at intervals upon the turning disc and cools it; otherwise it would become so hot from the friction that it could not be used. After the design has been cut on the emery-wheel all its rough edges are smoothed off on a stone of much finer grain. I can show you our gla.s.s cutters at work if you would care to see them."

"Oh, do let's see them, Uncle Bob," begged Jean.

"All right; but only for a few moments. We have already taken too much of Mr. Wyman's time, I fear. And besides, I must be back in town for luncheon," answered Mr. Cabot.