Sloss Furnaces National Historic Landmark
The technology of casting molten iron into bars called pigs changed dramatically over the years. Prior to 1931 casting at Sloss took place inside the cast shed. Men cut molds into the sand floor of the shed, allowing the molten iron to pour through the channels and into individual molds. The configuration of molds feeding off troughs gave rise to the term "pig" for the bar of iron—workers thought the molds resembled pigs suckling at the sow.
After 1931 casting was mechanized. Iron flowed from the furnace, down the curved runner and into the ladle car outside the shed. The ladle car then moved down the tracks to the pig casting machine, the remains of which you can see straight ahead.
The men who broke up and carried out the iron from the sand casting beds were called iron carriers. Edward Uehling, inventor of the mechanical pig casting machine, described their work this way: "When the iron had cooled down to the temperature of solidification, but was still red hot, the iron carriers began their task. They covered the pigs with a layer of sand, then put on shoes with thick wooden soles, walked on the hot iron, and with crowbars broke the pigs off the sow and with sledge hammers broke the sow into pieces the length of the pigs. This was as hot a job as a man could stand, but it had to be done. If the pigs were allowed to get cold, it would not only be more difficult to break the pigs off the sow and the sow pieces, but the iron could not be carried away in time to mold up [the sand] for the next cast...Only one man in ten is physically fit to be an iron carrier, and the best of them cannot stand up under the strain for many years...
The task of breaking up and carrying out the iron from the casting beds of even modest-size furnaces is not a fit one for human beings. If it were possible to employ horses, mules or oxen to do this work, the Society for the Prevention of Cruelty to Dumb Animals would have interfered long ago, and rightfully so."