Pittsburgh, PENNSYLVANIA - Rolling Mill - Nightwork - 1907: Pittsburgh's leading role in crucible steel - its first steel industry - is almost entirely forgotten today, eclipsed by the fiery Bessemer converters and oversize rolling mills. Beginning in the 1850s, successful crucible steel manufacturers, often depending on skilled workers from Sheffield, England, melted high-carbon blister steel and pure bar iron together at extreme heat. These skilled workers, hefting clay or graphite crucibles filled with 100 pounds of white-hot molten metal, made a fine grade of steel that was for many decades the choice for scissors, cutlery, piano wire, women's skirt hoops, and edge tools of all sorts. By 1877, the region's fourteen medium-scale crucible steel factories produced nearly three-fourths of the nation's output. In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness and to make the thickness uniform. The concept is similar to the rolling of dough. Roll stands holding pairs of rolls are grouped together into rolling mills that can quickly process metal, typically steel, into products such as structural steel (I-beams, angle stock, channel stock, and so on), bar stock, and rails. Most steel mills have rolling mill divisions that convert the semi-finished casting products into finished products. This Undivided Back Era gilded framed postcard, mailed in 1907, is in good condition, but there is a crease to the card's lower left-hand corner. Ullman's Gold Border Series. No. 3177.