Editing Cementation process (section)

==Process==
[[Image:Cementation_furnace,_Sheffield.jpg|thumb|right|The Doncaster Street cementation furnace in [[Sheffield]], [[England]]]]
The process begins with [[wrought iron]] and [[charcoal]].  It uses one or more long stone ''pots'' inside a furnace.  Typically, in [[Sheffield]], each pot was 14 feet by 4 feet and 3.5 feet deep.  Iron bars and charcoal are packed in alternating layers, with a top layer of charcoal and then refractory matter to make the pot or "coffin" airtight.  Some manufacturers used a mixture of powdered charcoal, [[soot]] and mineral [[salt (chemistry)|salt]]s, called ''cement powder''.  In larger works, up to 16 tons of iron were treated in each cycle, though it can be done on a small scale, such as in a small furnace or blacksmith's forge.

Depending on the thickness of the iron bars, the pots were then heated from below for a week or more.  Bars were regularly examined and when the correct condition was reached the heat was withdrawn and the pots were left until cool—usually around fourteen days.  The iron had gained a little over 1% in mass from the [[carbon]] in the charcoal, and had become heterogeneous bars of ''blister steel''.

The bars were then shortened, bound, heated and forge welded together to become ''shear steel''. It would be cut and re welded multiple times, with each new weld producing a more homogeneous, higher quality steel. This would be done at most 3-4 times, as more is unnecessary and could potentially cause carbon loss from the steel.   

Alternatively they could be broken up and melted in a crucible using a [[crucible steel|crucible furnace]] with a [[flux (metallurgy)|flux]] to become ''[[crucible steel]]'' (at the time also called ''cast steel''), a process devised by [[Benjamin Huntsman]] in Sheffield in the 1740s.