Sand casting with molten metal ranks as one of the oldest of the manufacturing technologies. For many years it was a dark art and its mysteries were known only to a select few. A sixteenth-century Italian metallurgist and arms maker, Vannoccio Biringuccio (1480-c. 1539), would change this with his seminal work, De la pirotechnia (1540). Published in Venice a year after Biringuccio's death, the book is a veritable enclyclopedia of metallurgical knowledge and constitutes some of the earliest printed information on sand casting and foundry techniques in general.
Born in Siena, Biringuccio, under the patronage of an Italian merchant politician and part-time tyrant, Pandolfo Petrucci, traveled widely throughout Italy and Germany, accumulating the information and experiences that he would summarize in his book.
During a typical sand-casting operation, a model or "pattern" of the item to be cast is positioned in a frame. Sand, moistened to bind it together, is then pressed closely around the pattern. This moist sand mix is a critical feature of the process and through the years various binding agents have been adopted, some of them quite unusual. Biringuccio himself recommended the use of human urine and the dregs from beer vats for the purpose.
When the frame is full and the sand rammed down, it is turned over and another frame temporarily attached. The process is then repeated, the frames separated, and the model carefully removed, leaving a cavity in each of the sand boxes that represents one half of the item to be cast. Channels ("sprues" and "runners") are cut into the sand to allow molten metal to be poured into the mold, and air to escape during the pouring. The frames are now securely reassembled together and the metal is poured.
