In the hand-blowing process six men are needed to make one bottle. There must be a gatherer to draw the glass from the furnace; a blower; a man to handle the mold; a man to chip off the bubble left by the blower; a shaper to finish the neck of the bottle; and a carrier-off to take the completed bottles to the lehr. Usually the gatherer is also the blower, in which case two men are used, one blowing while the other gathers for his turn; but on one platform I saw the somewhat unusual sight of one man doing all the blowing while another gathered for him. The pair used two wands, so that their production was the same as tho two men were gathering and blowing. This particular blower was making quart bottles, and he was well qualified for the job. He weighed, at a conservative estimate, two hundred and fifty pounds, and when he blew something had to happen. I arrived at his place of labor just as the shifts were being changed—a glass-furnace is worked continuously, in three eight-hour shifts—and as the little whistle blew to announce the end of his day's toil the giant grabbed the last wand, dropped it into the waiting mold, and blew a mighty blast. A bubble of glass sprang from the mouth of the mold, swelled to two feet in diameter, and burst with a bang, filling the air with shimmering flakes of glass, light enough to be wafted like motes. When the shining shower had settled and I had opened my eyes—it would not be pleasant to get an eyeful of those beautiful scraps—the huge blower was diminishing in perspective toward his dinner, and the furnace door was, for the moment, without its usual hustling congregation of workers. I made bold to investigate the platform.
Close to me glared the mouth of the furnace, with masses of silver threads depending from it like the beard of some fiery gulleted ogre—the strings of glass left by the withdrawal of the wand. The heat three feet away was enough to make sand melt and run like water, but I was not unpleasantly warm. This was because I stood at the focus of three tin pipes, thru which streams of cold air, fan-impelled, beat upon me. Without this cooling agent it would be impossible for men to work so close to the heat of the molten glass.
Later, in the cool offices of the company, where the roar of the furnaces penetrated only as a dull undertone, and electric fans whizzed away the heat of the summer afternoon, I learned more of the technique of the bottle industry. Each shape demanded by the trade requires a special mold, made of cast iron and cut according to the design submitted. There are, of course, standard shapes for standard bottles; these are alluded to (reversing the usual practise of metonymy) by using thing contained for container, as "ginger ales," "olives," "mustards," "sodas" and (low be it spoken) "beers." But when a firm places an order for bottles of a particular shape, or ones with lettering in relief on the glass, special molds must be made; and after the lot is finished the molds are useless till another order for that particular design comes in. A few standard molds are made so that plates with lettering can be inserted for customers who want trademarks or firm names on their bottles; but the great majority of the lettered bottles have their own molds, made especially for them and unable to be used for any other lot.
All bottles are blown in molds; it is in the handling of the molten glass and the actual blowing that machinery has come to take the place of men in the glass industry. The first type of machine to be developed was for blowing the bottle and finishing it, thus doing away with three of the six men formerly employed in making one bottle. In appearance the bottle-blowing machine is merely two circular platforms, revolving in the same horizontal plane, each carrying five molds. One of the platforms revolves close to the furnace door, and as each mold comes around it automatically opens and the gatherer draws from the furnace enough glass for the bottle which is being made at the time, and places it in the mold. The mold closes, and the platform turns on, bringing around another mold to the gatherer. Meanwhile a nozzle has snapped down over the first mold, shaping the neck of the bottle, and beginning the blowing. As the mold comes to a point diametrically opposite the furnace door it opens again, and a handler takes the blank, as the bottle is called at this stage, and places it in a mold on the second revolving platform. This mold closes and compressed air blows out the bottle as the platform revolves. As the mold comes around to the handler again it opens and the handler takes out the finished bottle, replacing it with a new blank drawn from the mold on the first platform. This operation necessitates only three men—a gatherer, a handler, and a carrier-off. It is also much faster than the old method—an average of about forty bottles per minute as against barely twenty.
A newer development of this machine does away with the gatherer. A long rod of refractory clay is given a churning movement in the mouth of the furnace, forcing the molten glass thru a tube. As enough glass for one bottle appears at the mouth of the tube a knife cuts the mass and the blob of glass falls into a trough which conveys it to the blank mold. By an ingenious device the same trough is made to feed three or four machines at one time. As many as fifty bottles a minute can be turned out by this combination blowing machine and feeder.
But the apotheosis of bottle-making is to be seen in another factory in the south Jersey district. Here it is the boast of the superintendents that from the time the sand goes out of the freight cars in which it is brought to the plant till the finished bottle is taken by the packer, no human hand touches the product; and their statement is amply confirmed by a trip thru the plant. The sand, coloring matter and cullet are in separate bins; an electrical conveyor takes enough of each for a batch to a mixing machine; from there the batch goes on a long belt to the furnace. At the front of the furnace, instead of doors or mouths, is a revolving pan, kept level full with the molten glass. Outside the furnace revolves a huge machine with ten arms, each of which carries its own mold and blowpipe. As each arm passes over the pan in the furnace the proper amount of glass is sucked into the mold by vacuum; the bottle is blown and shaped in the course of one revolution, and the mold, opening, drops the finished bottle into a rack which carries it to the lehr on a belt. It passes thru the lehr to the packers; and as each rack is emptied of its bottles the packers place it again on the belt, which carries it up to the machine, where it collects its cargo of hot bottles and conducts it again thru the lehr. The entire plant—mixing, feeding, actually making the bottles, delivery to the lehr, and packing—is synchronized exactly. Men unload the cars of sand—men pack the bottles. The intermediate period is entirely mechanical. The plant itself is as well lighted and ventilated as a department store, and except in the immediate vicinity of the furnace there is no heat felt above the daily temperature. The machines average well over a bottle a second, and by an exceedingly clever arrangement of electrical recording appliances an accurate record of the output of each machine, as well as the temperatures of the furnaces and lehrs, is kept in the offices of the company. The entire equipment is of the most modern, from the boilers and motors in the power-plant and producer-gas-plant to the packing platforms. In addition, the plant boasts a complete machine shop where all the molds are made and the machines repaired.
It is a far cry from human lung-power to the super-efficient machinery of the new plants; but it is the logical progress of human events, applying to every product of man's hands, from battleships to—bottles.
(New York World)