Sheets
The Rolling of Sheets
Most plates are rolled from slabs which are about 36 inches wide, but “sheets,” which are plates less than ³⁄₁₆″ thick are rolled from much smaller-sized slabs known as “sheet bars.” After “pulling out” into sheets these may be folded once or even more times, so that from two to eight thinner sheets are rolled at once. That they may not weld or stick together under the heavy pressure, they must be rolled colder than are single plates. They are later trimmed and pulled apart. Some mills start sheet bars of smaller size, for each sheet a separate piece, which, after drawing out somewhat are piled, two, three, four or five high. With coal or charcoal dust—either dry or mixed with water—between them, they are heated and rolled, the charcoal and coal dust keeping them from sticking together. After annealing, pickling, etc., they may be cold finished in polished rolls or otherwise treated according to the purpose for which they are intended. After straightening some are galvanized, others are tinned, blued or painted. Most of them are sold “black,” i.e., with no coating at all. Terneplate has a coating of 75% of lead and 25% of tin.