The previous process for making high-carbon steel first required cementation. Bars of wrought ( malleable) iron were baked at high temperature ( c 2,200 F) in closed brick troughs or "pots" with charcoal for several days until carbon had penetrated into the iron. Because blisters formed on the surface, it was called blister steel. Those bars were usually then further refined. They could be worked very quickly under trip hammers to make better steel for springs, tilted steel. Sometimes they would be cut up, welded into a block and hammered out again ( shear steel) and sometimes that block would be cut up welded and hammered out a second time (double shear steel) . This re-working was to try to mix the carbon evenly throughout the steel, as cementation tended to create bars that had more carbon closer to the surface. Any steel cutting tool, whether it's a drill bit, axe or chisel , will not have a very good working edge if the metal varies in hardness, and varying carbon content would vary the hardness. Having harder and softer spots in steel tools like hammers, punches and dies made them also more likely to crack. Shear steel and double shear steel were better than blister steel, but still were not very homogenous.

Huntsman used a different step after initial cementation. Blister steel chunks of about 1 pound were put into small fireclay crucibles (about 30 pounds in each), which had lids. They were fired to the point where the steel melted and pooled, which uniformly distributed the carbon ( and which allowed any slag inclusions to also melt and flow to the surface) . Each crucible would be pulled from the fire, one at a time, and an ingot poured. That was crucible steel. Getting the temperature to around 3,000 degrees F was undoubtedly much easier with coke than charcoal, but Huntsman's method involved more than that.

George Ede: The Management of Steel ( 1863)