Arthur Watts designed and built the New Lexington High Voltage Insulator Company plant and describes in general terms how to build a porcelain plant.

THE CONSTRUCTION AND EQUIPMENT OF A

WHITE WARE POTTERY.

BY

ARTHUR S. WATTS, NEW LEXINGTON, O.

For the past year I have devoted my entire time to the designing and erection of a 12 kiln china ware plant. From my experience along this line, I propose to offer the society my idea of a white ware plant, trusting that it may find some helpful suggestions from a study of my ideas. As I shall publish an outline plan of the buildings, it will be unnecessary to discuss their arrangement here. What I propose is to take up the various defects common in such plants, and offer what I propose as a correction.

While I approve of all practical labor-saving devices, I do not consider any mechanical device a good investment that will not save its cost in one year. We will first look to the power plant, which I will discuss in detail later. In my engine room, will be two engines and two dynamos. One of the latter will be used for power, and the other for light. In the average white ware plant, so little power is used beyond the clay shops, that none is supplied beyond this point. I propose to make use of motors wherever power is needed beyond the bisque kiln shed, as it is quite as economical and saves the long shafting otherwise necessary.

Adjoining my engine room, I propose a thoroughly equipped machine shop, where all work of the factory may be done.

In the clay rooms, the first subject that demands our attention is the material and clay sheds. Many factories have these sheds so located that a long haul is necessary to reach the slip house. I propose to make use of modern conveying machinery, and with a grain shovel inside of the car, I will be enabled to unload a car of material with one man in one-third the ordinary time. I also find that flint sand can be purchased for about $1.00 per ton, and even with the expense of installing tube or ball mills for grinding, the ground flint can be produced for much less than the market price. The same is the case with feldspar rock. What I propose is to install porcelain-lined tube mills and grind my own flint and spar.

The next practice that I propose to improve upon is the preparation of the body. We must have the body uniformly mixed, if our ware is to be of a uniform color and appearance. The flint and spar ordinarily used are materially coarser than the clay, and hence, especial care must be taken to have them thoroughly mixed. This can not be done in the old fashioned blunger. What I propose is a series of blungers, from which the body passes to a tube mill such as is commonly used for grinding Portland cement. This is the best rapid-grinding apparatus known for clay working, and by careful adjustment the body can be brought from this mill in a perfectly uniform and very fine condition. It has been my experience that this is the only successful means of overcoming cloudiness so common in American porcelain.

From the tube mill, my slip will pass through a trough, where I have installed a battery of horseshoe magnets, charged from my electric lighting line. By this method, I remove any particles of metallic iron that may have stolen into the mixture. I find this a very good thing, since about any factory, annoyance from a few specks of iron in a fine piece of ware is no uncommon occurrence.

The body then passes through the screen into the deep agitator. I will here explain what I consider an ideal clay slip screen. It is nothing more than a rectangular box 24x30 inches, made of heavy wood to stand jarring. It is set with one end raised about 10°, and the upper end is left open to permit the workings to pass out. The slip is introduced at the lower end. The shaking is produced by having the box supported on four straight steel springs, two at each end. A heavy cog wheel forces the box out of position until a cog can pass under, when the box flies back to its original position, striking either the next cog or a block set for the purpose. This produces a very strong jar, and frees all collected refuse from the surface of the screen, jarring it up the incline until it passes over the top. I have seen this type of screen work for months without needing any repair, and it possesses the advantage of requiring very little height, whereas, the ordinary screen requires from two to three feet of height, necessitating the placing of all blungers very high, and requiring a proportionately higher building.

From the deep agitator the slip goes to the press by means of the pump. If any one machine in a pottery may be considered the "potter's burden," it is the slip pump. Every potter has his own idea of a pump, but mine is a rubber-ball-valve pump. This works by a plunger, but instead of the ordinary brass or leather valve, it has a socket into which fits a rubber ball. This can not possibly get out of the cavity, and when it becomes worn too small, it can be replaced for a few cents, thus giving you practically a new valve. As the rubber takes all the wear, the socket lasts for years This pump gives less trouble where used than any that I have ever tried or seen tried, besides being cheaper than the brass valve commonly used. Another idea that I have proven to be thoroughly practical, is a pad under each sack on the press. Any slip-house man will tell you that it takes longer to put the last quarter of clay into a leaf than is consumed in pumping up the first three-quarters of the leaf. This is owing to the canvass sack being pressed tight against the iron leaf of the press, leaving no room for the water to run out. By placing a layer of coarse felt or canvas between the sack and the iron leaf, the water can soak out at any ordinary pressure as fast as the pump can force it in. This enables you to pump your press up to 100 pounds without stopping, and you will find that it will take less than one-half the time consumed by the old single sack method. I find further, that a press thus equipped will not burst and run, as the clay from the broken sack meets the cushion of felt or canvas and clogs, thus enabling the press-man to continue with his pumping, and perhaps use the broken sack the remainder of the day without any trouble. I also find this a great saving in sacks, as no loss is experienced from wear against the iron leaf.

From the press, the clay goes to the cellar. Here is the weak point in most white ware potteries, especially china plants. Ample room must be supplied for aging the body, as otherwise much loss is suffered from cracking. Most clay cellars are too cold. This is the worst condition possible where a bacterial growth is desired, as is the case here. The temperature of a clay cellar should never run below 76°, and an abundance of moisture should be provided. This condition I propose to insure by placing steam pipes next my ceiling. My walls will be lined with heavy oak plank, as will also the floors. The cellar will be of sufficient size that the clay may be aged for two weeks. I find that under proper conditions, a longer period of aging proves detrimental since the clay becomes rotten and full of tiny gas bubbles, which enlarge on burning and disfigure the ware.

The clay shops are on a level with the other floors of the factory, the additional height required being supplied above. This brings the main power shafts on a level with the power shafts of the second floors, except in the room above the slip room, and reduces the amount of belting necessary, while it insures a good dry floor for your slip house. The elevated floor above the slip house is used for a casting room, and no power is required, except for pumping up slip, which is done from below.

The glaze is all ground in ball mills and pumped across to the dipping rooms.

The clay, after aging, is pugged, and goes by means of a belt elevator to the various departments above. The work shop occupies the second floor, and is equipped with oval jollies, etc., reducing hand labor to the minimum. The ware, after being inspected, goes to the green room on the first floor. This room is divided into four sections; heavy-flat, thin-flat, jollied-hollow, and cast-hollow, enabling the placer to find what he wants without any trouble or delay.

We now come to the placing of the green ware for the bisque kilns. Here the handling of saggers and placing material confronts us. It is customary to place extra saggers about the kiln-shed when not in use, but to this practice I lay much of our dirty ware. It is certain that with a clean, light place for the saggers when not in use, and where the placer may fill the sagger, a much neater and more satisfactory result will be obtained than in a dirty, smoky kiln-shed. I therefor propose a 25 foot room, between the green wareroom and the bisque kiln-shed, where saggers may be stored and filled.

To the subject of kilns, I have given some attention, and while I have not been able to convert others to my views, I am convinced that the center stack down draft kiln is the ideal for white ware, as well as for tile. I can not see the economy or necessity of retaining the old up-draft kiln. Any one who has studied the workings of an up-draft white ware kiln, knows that the outside ring is solid-flat ware, laid in flint or sand, while the center of the kiln consists of hollow ware. Between this and the center, is a great area that is too soft for flat ware, and too hard for hollow ware. The ware taken from this area is never right. Why can we not use a center-stack down-draft kiln, which will give uniform results, and burn only such ware in a kiln as can be all burned at the same temperature? This would necessitate setting an entire kiln of hollow, for every two kilns of flat, but this could be done, as it would mean two kilns of hollow ware, and four kilns of flat ware each week, in a 12 kiln plant. The hollow ware could be burned at a lower cone than the solid-flat ware, and this would produce a product uniform in color and hardness.

The bisque ware goes by a gravity conveyor to the bisque warehouse. Here, I would use power to assist me in removing the sand or flint from the ware. For cleaning all pieces less than three and one-half inches in diameter, such as creams, butter slips, and small heavy sauce dishes, I use a hickory-lined ball mill filled with sand. The ware is placed in the mill and sand added until it is nearly full. The mill is run until the dishes are clean. The large round ware is cleaned on a wheel. The irregular shapes are cleaned by hand. As soon as the ware is cleaned, it is dusted and placed in tight boxes on wheels, in which it goes to the dipping room adjoining. As the ware is glazed, it is placed in a dryer with doors at both sides, enabling the glost kiln placer to reach the ware without entering the glazing room. This dryer also confines the heat to the glazed ware, and makes a much more agreeable dipping room than we generally find. From the glost kiln, which is also a center-stack down-draft, the ware goes to the cleaning and sorting room, where it is carefully sorted, and such ware as must be decorated, in order to be made saleable, is taken to the decorating warehouse, while the first and second-class ware goes to the glost warehouse. Ware should not be decorated until ordered, and then go directly from the decorating kilns to the packing department, where it is to be wrapped and packed.

Crates and casks for shipping ware will be made on the premises, and brought by gravity conveyor directly into the packing room. Straw for packing will be handled by the same method, hence no quantity of packing material need accumulate in the packing rooms where it might cause a disastrous fire.

Coal for my kilns will be run on an elevated switch, and bottom dump cars being used, no expense will be incurred in unloading. The coal will be distributed about the kilns by means of cars running on overhead tracks and so arranged that the loaded car carries the empty car back.

The sagger shop is so located that the carry to the bisque kilns is the shortest possible.

It has been suggested that my ware houses are small, but actual experience has proven that they are ample to carry a $150,000 stock, and I consider that any concern which accumulates more than that amount of stock must have some cause for being unable to dispose of their product, and should suspend operation until their stock is reduced or the cause of unsalability overcome.

In closing, I desire to remind you that these are simply suggestions, and while they have proven practical wherever I have seen them used, they are open to criticism and would doubtless require changing to suit the location and existing conditions. For a level site and unlimited space, however, I feel that I can assure you that a plant of this description and plan would enable the owner to produce ware at a much lower cost and of a better quality than much that is produced today.