Page:History of Goodhue County, Minnesota.djvu/711

 HISTORY OF GOODHUE COl N'l "V 623 throughoul the United States, and even in foreign countries, the annual output being aboul 3,500 carloads. While a specialty is made of sewer pipe from four to twenty-four inches in diameter, and even Larger, there are also made culverl pipe, drain til wed curbing, water pipe, gas pipe, chimney hoods, well coping and other clay products in the pipe line. Tests have proven the advantages of the pipe shipped from Red Wing. Being a vitri- fied, salt glazed pipe, it is weather proof, rust proof, frost proof, and. so far as chemical tests can determine, time proof. It is not affected by electric currents, and having no purrs can be made absolutely germ proof. The process of making the pipe is most interesting. The clay is brought in train loads from the day beds in Goodhue, and conveyed in buckets from the cars to the grinder. This grinder is a bowl about ten feet across, with a pair of circular knives that work back and forth and revolve at the same time, the bowl itself having a rapid rotation. To the ground clay is added a bit of ground potsherd, and enough water to reduce it to a consistency suited to the next process. This pasty or dough- like mass is then emptied with a scoop into buckets, which are carried to the head of the press, where the clay is forced through the casting by seventy tons steam pressure from a forty-four- inch cylinder that squeezes out every air bubble. The collar at the socket end is moulded at the same time. As the pipe comes from the press it is taken on hand trucks to the drying room, where a sponger trims off the rough edge, after which it is set on a board to set for twenty-four hours. The next day the other end is trimmed to exact length and true shape. It then stands in the drying room a week or ten days, the temperature being increased from 110 to 125 during this drying process. The pipe is then ready for the kiln. Within the kiln, the pipes are ar- ranged with the greatest skill, the object being to get in as many as possible without crowding, and yet to have them stand true so that they will not warp. After this is arranged satisfactorily, the openings in the dome are sealed up, the door is walled up with brick and clay. Fires are then started in a series of grates around the kilns, and gradually increased until a temperature of high degree is reached, an ingenious system being arranged to distribute the heat evenly among the pipe in the kiln. At the period of the most intense heat, salt is thrown in, giving the pipe the smooth glazed finish so much admired and desired.. After four days of this baking, the kiln is gradually allowed to cool for four days, the heat being released gradually to avoid combustion of nearby woodwork. The pipe is then tested with a hammer, and as a final process is sorted and piled up in rows in the yards ready for shipping.